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2019 Volume 35 Issue 8
2019, 35(8): 1321-1339
doi: 10.11862/CJIC.2019.167
Abstract:
Titanium dioxide (TiO2) is a cheap and non-toxic material with excellent stability and photocatalytic redox ability, therefore it has attracted considerable interest in academy and industry. However, two intrinsic defects have limited its applications, including the low utilization of visible light, and fast recombination of photogenerated electron-hole pairs. These two defects could be remedied by constructing TiO2 based Z-scheme heterojunction which also shows stronger oxidation or reduction properties than TiO2. In this review, we summarized the band alignment and the principles of electron transfer for pure TiO2 photocatalysts, heterojunction photocatalysts and TiO2 based Z-scheme heterojunction photocatalysts. Moreover, we discussed the similarity and difference between Z-scheme heterojunction and type-Ⅱ heterojunction, and some methods to distinguish them were developed. At the end, we tried to summarize applications of the TiO2 based Z-scheme heterojunction in photocatalysis.
Titanium dioxide (TiO2) is a cheap and non-toxic material with excellent stability and photocatalytic redox ability, therefore it has attracted considerable interest in academy and industry. However, two intrinsic defects have limited its applications, including the low utilization of visible light, and fast recombination of photogenerated electron-hole pairs. These two defects could be remedied by constructing TiO2 based Z-scheme heterojunction which also shows stronger oxidation or reduction properties than TiO2. In this review, we summarized the band alignment and the principles of electron transfer for pure TiO2 photocatalysts, heterojunction photocatalysts and TiO2 based Z-scheme heterojunction photocatalysts. Moreover, we discussed the similarity and difference between Z-scheme heterojunction and type-Ⅱ heterojunction, and some methods to distinguish them were developed. At the end, we tried to summarize applications of the TiO2 based Z-scheme heterojunction in photocatalysis.
2019, 35(8): 1340-1348
doi: 10.11862/CJIC.2019.156
Abstract:
Two iridium complexes[Ir(ppy)(qbiH)]NO3 (1·NO3) and[Ir(ppy)(qbi)] (2) have been synthesized. Their crystal structures indicate that an[Ir(ppy)2]+ unit is chelated by a neutral benzoimidazole-based ligand qbiH in 1·NO3, while anion ligand qbi- in 2. The different deprotonation degrees of ligands qbiH and qbi- in the two complexes lead to their clear differences in luminescence both in solution and in solid state. Complexes 1·NO3 and 2 in CH2Cl2 show the emissions at 581 and 574 nm, respectively. In solid state, a red emission at 611 nm was observed for 1·NO3, while an orange emission at 598 nm for 2. It is interesting that both 1·NO3 and 2 in solid state exhibited luminescence switching between red emission and orange emission, upon meeting Et3N/TFA vapor. This is due to the acid/base-induced structural interconversion between ligand qbiH and ligand qbi- in complexes 1·NO3 and 2. Moreover, we discuss the relationship between structure and luminescence for 1·NO3 and 2.
Two iridium complexes[Ir(ppy)(qbiH)]NO3 (1·NO3) and[Ir(ppy)(qbi)] (2) have been synthesized. Their crystal structures indicate that an[Ir(ppy)2]+ unit is chelated by a neutral benzoimidazole-based ligand qbiH in 1·NO3, while anion ligand qbi- in 2. The different deprotonation degrees of ligands qbiH and qbi- in the two complexes lead to their clear differences in luminescence both in solution and in solid state. Complexes 1·NO3 and 2 in CH2Cl2 show the emissions at 581 and 574 nm, respectively. In solid state, a red emission at 611 nm was observed for 1·NO3, while an orange emission at 598 nm for 2. It is interesting that both 1·NO3 and 2 in solid state exhibited luminescence switching between red emission and orange emission, upon meeting Et3N/TFA vapor. This is due to the acid/base-induced structural interconversion between ligand qbiH and ligand qbi- in complexes 1·NO3 and 2. Moreover, we discuss the relationship between structure and luminescence for 1·NO3 and 2.
2019, 35(8): 1427-1435
doi: 10.11862/CJIC.2019.175
Abstract:
The potassium modified Activated Semi-coke (K/ASC) for SO2 removal was prepared using potassium carbonate (K2CO3) by the impregnation method. The ASC modified by 10%(w/w) K2CO3 (K10) exhibited good SO2 removal efficiency at 120℃. From 400 to 700℃, the higher the regeneration temperature is, the better is the desulfurization activity of K10 after regeneration. Cyclic regeneration of K10 (K10-R-600-n) showed that the sample had the best desulfurization performance after four regeneration cycles (K10-R-600-4), and its sulfur capacity was 68.9 mg·g-1, 24.37% higher than that of K10 (55.4 mg·g-1). The desulfurization products are divided into physisorbed SO2, H2SO4 and sulfate. The deposition of sulfate, which does not decompose after regeneration, results in the decrease of the desulfurization activity. The sulfur capacity of the sample after ten regeneration cycles (K10-R-600-10) remained 70% that of the fresh K10.
The potassium modified Activated Semi-coke (K/ASC) for SO2 removal was prepared using potassium carbonate (K2CO3) by the impregnation method. The ASC modified by 10%(w/w) K2CO3 (K10) exhibited good SO2 removal efficiency at 120℃. From 400 to 700℃, the higher the regeneration temperature is, the better is the desulfurization activity of K10 after regeneration. Cyclic regeneration of K10 (K10-R-600-n) showed that the sample had the best desulfurization performance after four regeneration cycles (K10-R-600-4), and its sulfur capacity was 68.9 mg·g-1, 24.37% higher than that of K10 (55.4 mg·g-1). The desulfurization products are divided into physisorbed SO2, H2SO4 and sulfate. The deposition of sulfate, which does not decompose after regeneration, results in the decrease of the desulfurization activity. The sulfur capacity of the sample after ten regeneration cycles (K10-R-600-10) remained 70% that of the fresh K10.
2019, 35(8): 1436-1444
doi: 10.11862/CJIC.2019.174
Abstract:
Two novel discrete complexes with Ag(Ⅰ) centers based on the double Schiff-base ligand, 3, 6-bis(2-(4-oxide-quinoxaline)-yl)-4, 5-diaza-3, 5-octadiene (L), have been synthesized. The obtained Ag(Ⅰ) complexes, [Ag8(L)8](BF4)8·CH2Cl2·3CH3OH (1) and[Ag4(L)4](PF6)4·CH2Cl2 (2), were fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Both complexes exist as dimers. Through hydrogen bonds, uncoordinated counter ions and discrete molecular complex building blocks formed one-dimensional (1D) or two-dimensional (2D) frameworks.
Two novel discrete complexes with Ag(Ⅰ) centers based on the double Schiff-base ligand, 3, 6-bis(2-(4-oxide-quinoxaline)-yl)-4, 5-diaza-3, 5-octadiene (L), have been synthesized. The obtained Ag(Ⅰ) complexes, [Ag8(L)8](BF4)8·CH2Cl2·3CH3OH (1) and[Ag4(L)4](PF6)4·CH2Cl2 (2), were fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Both complexes exist as dimers. Through hydrogen bonds, uncoordinated counter ions and discrete molecular complex building blocks formed one-dimensional (1D) or two-dimensional (2D) frameworks.
2019, 35(8): 1445-1454
doi: 10.11862/CJIC.2019.166
Abstract:
To expand the application fields of rare earth fluorescence complexes, and meet the requirements of high sensitivity and selectivity for the detection of trace chromium in aqueous solution, we prepared a sensitive luminescence sensor for Cr3+ ion based on a water dispersed nano-sized amorphous luminescence terbium complex with methyl salicylate (A-MS-Tb). It was found that the synthesized A-MS-Tb is an amorphous precipitation with particle size ranging from 50 to 100 nm and similar composition to the reported crystalline MS-Tb(C-MS-Tb). A-MS-Tb showed strong green luminescence at 494, 549, 591, 625 nm, which belongs to the energy level transition of 5D4→7FJ (J=6, 5, 4, 3) of Tb3+, respectively. The difference between A-MS-Tb and the reported C-MS-Tb lies in the stability and dispersion performance towards water which is very important for expanding its application as materials and sensors. In particularly, with the addition of Cr3+ into the water suspension of A-MS-Tb, the coordination between the ligand and Tb3+ is weakened, causing its green fluorescence to be quenched. Therefore, a highly sensitive sensor for detecting Cr3+ was established, and the sensitivity, selectivity and anti-interference ability was evaluated.
To expand the application fields of rare earth fluorescence complexes, and meet the requirements of high sensitivity and selectivity for the detection of trace chromium in aqueous solution, we prepared a sensitive luminescence sensor for Cr3+ ion based on a water dispersed nano-sized amorphous luminescence terbium complex with methyl salicylate (A-MS-Tb). It was found that the synthesized A-MS-Tb is an amorphous precipitation with particle size ranging from 50 to 100 nm and similar composition to the reported crystalline MS-Tb(C-MS-Tb). A-MS-Tb showed strong green luminescence at 494, 549, 591, 625 nm, which belongs to the energy level transition of 5D4→7FJ (J=6, 5, 4, 3) of Tb3+, respectively. The difference between A-MS-Tb and the reported C-MS-Tb lies in the stability and dispersion performance towards water which is very important for expanding its application as materials and sensors. In particularly, with the addition of Cr3+ into the water suspension of A-MS-Tb, the coordination between the ligand and Tb3+ is weakened, causing its green fluorescence to be quenched. Therefore, a highly sensitive sensor for detecting Cr3+ was established, and the sensitivity, selectivity and anti-interference ability was evaluated.
2019, 35(8): 1455-1462
doi: 10.11862/CJIC.2019.148
Abstract:
Herein, nickel phosphides nanoparticles with different phases were successfully prepared by multi-step calcination and phosphidation process at low temperature using Ni based MOF (Ni-MOF) as the precursor. The resulting materials were applied to the hydrogen evolution reaction (HER) catalyst, Ni1P1-500 obtained at a mass ratio of Ni@C to red phosphorus of 1:1 and a pyrolysis temperature of 500℃ exhibited a remarkably enhanced electrocatalytic performance with a current density of 10 mA·cm-2 at an overpotential of 178 mV and a superior durability for the HER in acid media. A small Tafel slope of 62 mV·dec-1 revealed a Desorption-Heyrovsky mechanism during the HER. The excellent electrocatalytic performance might be ascribed to the presence of the proton acceptor (P site) and hydride-acceptor (Ni site) centers on the surface of nickel phosphide.
Herein, nickel phosphides nanoparticles with different phases were successfully prepared by multi-step calcination and phosphidation process at low temperature using Ni based MOF (Ni-MOF) as the precursor. The resulting materials were applied to the hydrogen evolution reaction (HER) catalyst, Ni1P1-500 obtained at a mass ratio of Ni@C to red phosphorus of 1:1 and a pyrolysis temperature of 500℃ exhibited a remarkably enhanced electrocatalytic performance with a current density of 10 mA·cm-2 at an overpotential of 178 mV and a superior durability for the HER in acid media. A small Tafel slope of 62 mV·dec-1 revealed a Desorption-Heyrovsky mechanism during the HER. The excellent electrocatalytic performance might be ascribed to the presence of the proton acceptor (P site) and hydride-acceptor (Ni site) centers on the surface of nickel phosphide.
2019, 35(8): 1463-1469
doi: 10.11862/CJIC.2019.169
Abstract:
Three Cu(Ⅱ) complexes, [Cu(L)Br]·DMF (1), [Cu(L)Cl]·2H2O (2), and [Cu2(L)2(SO4)]·H2O·CH3OH (3) (HL=1-(3-ethylpyrazin-2-yl)ethylidene)-4-methylthiosemicarbazide) have been synthesized and structurally determined by single-crystal X-ray diffraction. The results show that the Cu(Ⅱ) ion in 1 and 2 is surrounded by one anionic thiosemicarbazone ligand with N2S donor set and one halide ion (bromide for 1 and chloride for 2), thus giving a distorted planar square coordination geometry. However, in the dimeric complex 3, two Cu(Ⅱ) ions were doubly bridged by two S atoms of two TSC ligands to form a Cu2S2 core with Cu…Cu distance of 0.318 0 nm. Each of the Cu(Ⅱ) ions is also coordinated by two nitrogen atoms from one TSC ligand and one oxygen atom from the η2-SO42- at the outer axial site, with a distorted square pyramid coordination geometry. Moreover, the fluorescence spectra indicate that the interactions of the complexes with DNA are stronger than that of the thiosemicarbazone ligand.
Three Cu(Ⅱ) complexes, [Cu(L)Br]·DMF (1), [Cu(L)Cl]·2H2O (2), and [Cu2(L)2(SO4)]·H2O·CH3OH (3) (HL=1-(3-ethylpyrazin-2-yl)ethylidene)-4-methylthiosemicarbazide) have been synthesized and structurally determined by single-crystal X-ray diffraction. The results show that the Cu(Ⅱ) ion in 1 and 2 is surrounded by one anionic thiosemicarbazone ligand with N2S donor set and one halide ion (bromide for 1 and chloride for 2), thus giving a distorted planar square coordination geometry. However, in the dimeric complex 3, two Cu(Ⅱ) ions were doubly bridged by two S atoms of two TSC ligands to form a Cu2S2 core with Cu…Cu distance of 0.318 0 nm. Each of the Cu(Ⅱ) ions is also coordinated by two nitrogen atoms from one TSC ligand and one oxygen atom from the η2-SO42- at the outer axial site, with a distorted square pyramid coordination geometry. Moreover, the fluorescence spectra indicate that the interactions of the complexes with DNA are stronger than that of the thiosemicarbazone ligand.
2019, 35(8): 1470-1476
doi: 10.11862/CJIC.2019.162
Abstract:
Coral-like rutile titania (Rut-dg) was synthesized by solvothermal method in diethylene glycol solution. Scanning electron microscope (SEM) and X-ray diffraction (XRD) indicated the spherical particles were homogeneously dispersed with the diameter about 1 μm, consisting regular arranged branches on the surface with diameter less than 10 nm. The BET surface area was as large as 228 m2·g-1, more than 7 times of commercial rutile titania sample. Given its unique morphology, the Rut-dg showed superior photocatalytic activity with hydrogen evolution 25 000 μmol·g-1·h-1 under ultraviolet irradiation, 50% higher than P25 and 13 times of commercial rutile sample. The hydrogen production under visible light was 270 μmol·g-1·h-1, while P25 and commercial rutile had no obvious activity. Further investigation demonstrated that no organics could be detected on the surface of Rut-dg, indicating the coral-like structures played the key role for the photocatalytic activity. After calcined at 300℃, the coral-like structures were sintered obviously and the surface area decreased by 50%. Meanwhile, the hydrogen production decreased by 15%~25%, also implying that the coral-like structures facilitated the hydrogen production dramatically.
Coral-like rutile titania (Rut-dg) was synthesized by solvothermal method in diethylene glycol solution. Scanning electron microscope (SEM) and X-ray diffraction (XRD) indicated the spherical particles were homogeneously dispersed with the diameter about 1 μm, consisting regular arranged branches on the surface with diameter less than 10 nm. The BET surface area was as large as 228 m2·g-1, more than 7 times of commercial rutile titania sample. Given its unique morphology, the Rut-dg showed superior photocatalytic activity with hydrogen evolution 25 000 μmol·g-1·h-1 under ultraviolet irradiation, 50% higher than P25 and 13 times of commercial rutile sample. The hydrogen production under visible light was 270 μmol·g-1·h-1, while P25 and commercial rutile had no obvious activity. Further investigation demonstrated that no organics could be detected on the surface of Rut-dg, indicating the coral-like structures played the key role for the photocatalytic activity. After calcined at 300℃, the coral-like structures were sintered obviously and the surface area decreased by 50%. Meanwhile, the hydrogen production decreased by 15%~25%, also implying that the coral-like structures facilitated the hydrogen production dramatically.
2019, 35(8): 1477-1484
doi: 10.11862/CJIC.2019.189
Abstract:
The reaction between nickel nitrate and halogenated salen-type Schiff-base ligand in methanol solution led to the isolation of two new salen nickel(Ⅱ) complexes[Ni(3, 5-Cl-salcy)] (1) and[Ni(3-Cl-salcy)] (2), where 3, 5-Cl-salcyH2=N, N'-(±)-bis(3, 5-dichlorosalicylidene)cyclohexane-1, 2-diamine and 3-Cl-salcyH2=N, N'-(±)-bis(3-chloro-salicylidene)cyclohexane-1, 2-diamine. The crystal structures of complexes 1 and 2 were structurally characterized by single-crystal X-ray diffraction. Structural analysis reveals that the basic units of both complexes all consist of one nickel(Ⅱ) ion in[N2O2] coordination sphere, forming similar square planar geometries. PLATON software analysis indicates that there is not any hydrogen bond exists in the crystal structure of 1, and only unclassical hydrogen bonds exist in 2. However, Hirshfeld surface analysis shows that, although the strength of halogen atoms formed hydrogen bonds are weak, the C-H…X bonds play an important role in stabilization of three-dimensional networks of both complexes. Moreover, by comparison of the two complexes, we found that the difference in the number of halogen atoms in the ligand can have a very important influence on the proportion of weak exchange in the crystal.
The reaction between nickel nitrate and halogenated salen-type Schiff-base ligand in methanol solution led to the isolation of two new salen nickel(Ⅱ) complexes[Ni(3, 5-Cl-salcy)] (1) and[Ni(3-Cl-salcy)] (2), where 3, 5-Cl-salcyH2=N, N'-(±)-bis(3, 5-dichlorosalicylidene)cyclohexane-1, 2-diamine and 3-Cl-salcyH2=N, N'-(±)-bis(3-chloro-salicylidene)cyclohexane-1, 2-diamine. The crystal structures of complexes 1 and 2 were structurally characterized by single-crystal X-ray diffraction. Structural analysis reveals that the basic units of both complexes all consist of one nickel(Ⅱ) ion in[N2O2] coordination sphere, forming similar square planar geometries. PLATON software analysis indicates that there is not any hydrogen bond exists in the crystal structure of 1, and only unclassical hydrogen bonds exist in 2. However, Hirshfeld surface analysis shows that, although the strength of halogen atoms formed hydrogen bonds are weak, the C-H…X bonds play an important role in stabilization of three-dimensional networks of both complexes. Moreover, by comparison of the two complexes, we found that the difference in the number of halogen atoms in the ligand can have a very important influence on the proportion of weak exchange in the crystal.
2019, 35(8): 1485-1492
doi: 10.11862/CJIC.2019.165
Abstract:
The layered Co3O4 nanosheets with porous nature on Ti mesh were adopted to optimize the transfer resistance by a facile hydrothermal method. The synthesized materials were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical techniques. The results showed that the materials consisted of well-arranged micrometer length rectangular 2D flakes with uniform pore distribution. This unique microstructure obtained the electrode lower transfer resistance, higher structure stability, and better electrochemical performance for supercapacitor. The 2D porous layered Co3O4 nanosheet could achieve a relatively good capacitance retention of 91.8% at a current density of 100 mA·g-1 after 1 000 cycles and a low transfer resistance (Rct) of 0.29 Ω. These remarkable supercapacitive performances are attributed to the rationally 2D layered structure on flexible Ti mesh substrate, high utilization ratio of active materials of the flexible Co3O4/Ti electrode.
The layered Co3O4 nanosheets with porous nature on Ti mesh were adopted to optimize the transfer resistance by a facile hydrothermal method. The synthesized materials were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical techniques. The results showed that the materials consisted of well-arranged micrometer length rectangular 2D flakes with uniform pore distribution. This unique microstructure obtained the electrode lower transfer resistance, higher structure stability, and better electrochemical performance for supercapacitor. The 2D porous layered Co3O4 nanosheet could achieve a relatively good capacitance retention of 91.8% at a current density of 100 mA·g-1 after 1 000 cycles and a low transfer resistance (Rct) of 0.29 Ω. These remarkable supercapacitive performances are attributed to the rationally 2D layered structure on flexible Ti mesh substrate, high utilization ratio of active materials of the flexible Co3O4/Ti electrode.
2019, 35(8): 1493-1499
doi: 10.11862/CJIC.2019.178
Abstract:
A novel highly ordered carbon tube (OCT) arrays derived from palm tree fiber by carbonization and activation with KOH was prepared and used as hosts for lithium sulfur battery. The OCT possessed large specific area and pore volume, which could effectively store sulfur. The method was clean, facile and low cost. Moreover, the S@OCT composite exhibited admirable electrochemical performances. The S@OCT with 65%(w/w) sulfur delivered an initial discharge capacity of 1 255.2 mAh·g-1 (1.8 mAh·cm-2) and retained 756.9 mAh·g-1 (1.09 mAh·cm-2) at the current rate of 0.2C after 100 cycles with a high coulomb efficiency. What's more, when tested at 5C, its initial capacity was up to 649.1 mAh·g-1 (0.93 mA h·cm-2) and retained 504.2 mAh·g1 (0.72 mAh·cm-2) after 100 cycles.
A novel highly ordered carbon tube (OCT) arrays derived from palm tree fiber by carbonization and activation with KOH was prepared and used as hosts for lithium sulfur battery. The OCT possessed large specific area and pore volume, which could effectively store sulfur. The method was clean, facile and low cost. Moreover, the S@OCT composite exhibited admirable electrochemical performances. The S@OCT with 65%(w/w) sulfur delivered an initial discharge capacity of 1 255.2 mAh·g-1 (1.8 mAh·cm-2) and retained 756.9 mAh·g-1 (1.09 mAh·cm-2) at the current rate of 0.2C after 100 cycles with a high coulomb efficiency. What's more, when tested at 5C, its initial capacity was up to 649.1 mAh·g-1 (0.93 mA h·cm-2) and retained 504.2 mAh·g1 (0.72 mAh·cm-2) after 100 cycles.
2019, 35(8): 1500-1508
doi: 10.11862/CJIC.2019.184
Abstract:
Three dinuclear Ru(Ⅱ)-arene complexes[Ru2(η6-p-bip)2(1, 3-bib)2XY]X2 (X=Y=Cl- (1), X=Y=Br- (2), X=I- and Y=Cl- (3); 1, 3-bib=1, 3-di(1H-imidazol-1-yl)benzene, p-bip=biphenyl) were synthesized and fully characterized by 1H NMR and ESI-MS. Single crystal X-ray diffractions studies showed that complex 1 owns a rigid M2L2 bowl-like structure, where one Cl- is trapped inside the cavity to balance the charge. Complex 3 showed the best anticancer activities among complexes 1~3. The IC50 value of 3 towards to human lung cancer cells (A549) reached to 13.9 μmol·L-1, which is comparable to that of cisplatin (IC50=15.2 μmol·L-1). Complexes 1~3 have shown strong interactions with DNA and could induce the unwinding of the DNA superhelix structure.
Three dinuclear Ru(Ⅱ)-arene complexes[Ru2(η6-p-bip)2(1, 3-bib)2XY]X2 (X=Y=Cl- (1), X=Y=Br- (2), X=I- and Y=Cl- (3); 1, 3-bib=1, 3-di(1H-imidazol-1-yl)benzene, p-bip=biphenyl) were synthesized and fully characterized by 1H NMR and ESI-MS. Single crystal X-ray diffractions studies showed that complex 1 owns a rigid M2L2 bowl-like structure, where one Cl- is trapped inside the cavity to balance the charge. Complex 3 showed the best anticancer activities among complexes 1~3. The IC50 value of 3 towards to human lung cancer cells (A549) reached to 13.9 μmol·L-1, which is comparable to that of cisplatin (IC50=15.2 μmol·L-1). Complexes 1~3 have shown strong interactions with DNA and could induce the unwinding of the DNA superhelix structure.
2019, 35(8): 1509-1519
doi: 10.11862/CJIC.2019.172
Abstract:
Three-dimensional (3D) porous thin films of AuPd and AgPd foams comprised of nanodendrites possess superior catalytic activity for the production of high-quality H2 from formic acid decomposition at room temperature. The high catalytic activity was attributed to the presence of abundant active sites like steps, corners, kinks and edges in the nanodendrites, and to the electronic effect. Besides the high activity, there were some more advantages for the nanodendrtic alloy foam films. For example, the foam films could be quickly electrodeposited in 5 min on a Ti substrate utilizing the template of hydrogen bubbles without needing organic additives, and it could be used directly for the hydrogen production without post-treatments. The hydrogen production was easily controllable, and we could get hydrogen and stop hydrogen production just by immersing the electrodeposited foam film into and pulling it out of the solution of HCOOH+HCOONa. The foam films could also be easily reactivated either by drying after water cleaning or by potential cycling in H2SO4 solution.
Three-dimensional (3D) porous thin films of AuPd and AgPd foams comprised of nanodendrites possess superior catalytic activity for the production of high-quality H2 from formic acid decomposition at room temperature. The high catalytic activity was attributed to the presence of abundant active sites like steps, corners, kinks and edges in the nanodendrites, and to the electronic effect. Besides the high activity, there were some more advantages for the nanodendrtic alloy foam films. For example, the foam films could be quickly electrodeposited in 5 min on a Ti substrate utilizing the template of hydrogen bubbles without needing organic additives, and it could be used directly for the hydrogen production without post-treatments. The hydrogen production was easily controllable, and we could get hydrogen and stop hydrogen production just by immersing the electrodeposited foam film into and pulling it out of the solution of HCOOH+HCOONa. The foam films could also be easily reactivated either by drying after water cleaning or by potential cycling in H2SO4 solution.
2019, 35(8): 1349-1356
doi: 10.11862/CJIC.2019.173
Abstract:
Two kinds of sulfonic-fictionalized organic polystyrene/inorganic zirconium hydrogen phosphate heterogeneous catalysts were firstly prepared. The catalysts were characterized by Fourier infrared spectroscopy (FT-IR), N2 adsorption-desorption test, X-ray diffraction (XRD) and scanning electron microscope (SEM). A possible model of the catalyst was proposed. Secondly, the catalytic performance of heterogeneous catalysts was investigated in the epoxidation of soybean oil. The results showed that the heterogeneous catalysts could effectively catalyze epoxidation of soybean oil with tert-butyl hydroperoxide (TBHP) as oxidant. Compared with catalyst 1 (sulfonic-functionalized zirconium oligo-polystyrenyl phosphonate-phosphate), catalyst 2 (sulfonic-functionalized zirconium poly(styrene-phenylvinylphosphonate)-phosphate) showed higher catalytic activity under the same conditions (Yield:58.6% vs 53.3%). It is mainly attributed to the larger specific surface area, pore volume and pore size of catalyst 2, which provides sufficient catalytic sites for substrate and catalyst contact. Finally, after repeated use for 7 times of the catalyst 2, there was no significant decrease in catalytic activity. Interestingly, after the end of the 8th reaction, the catalyst was allowed to stand in 2 mol·L-1 dilute hydrochloric acid for overnight, and the catalytic activity was restored again at the 9th and 10th cycle.
Two kinds of sulfonic-fictionalized organic polystyrene/inorganic zirconium hydrogen phosphate heterogeneous catalysts were firstly prepared. The catalysts were characterized by Fourier infrared spectroscopy (FT-IR), N2 adsorption-desorption test, X-ray diffraction (XRD) and scanning electron microscope (SEM). A possible model of the catalyst was proposed. Secondly, the catalytic performance of heterogeneous catalysts was investigated in the epoxidation of soybean oil. The results showed that the heterogeneous catalysts could effectively catalyze epoxidation of soybean oil with tert-butyl hydroperoxide (TBHP) as oxidant. Compared with catalyst 1 (sulfonic-functionalized zirconium oligo-polystyrenyl phosphonate-phosphate), catalyst 2 (sulfonic-functionalized zirconium poly(styrene-phenylvinylphosphonate)-phosphate) showed higher catalytic activity under the same conditions (Yield:58.6% vs 53.3%). It is mainly attributed to the larger specific surface area, pore volume and pore size of catalyst 2, which provides sufficient catalytic sites for substrate and catalyst contact. Finally, after repeated use for 7 times of the catalyst 2, there was no significant decrease in catalytic activity. Interestingly, after the end of the 8th reaction, the catalyst was allowed to stand in 2 mol·L-1 dilute hydrochloric acid for overnight, and the catalytic activity was restored again at the 9th and 10th cycle.
2019, 35(8): 1357-1362
doi: 10.11862/CJIC.2019.152
Abstract:
BaO-Al2O3-SiO2 (BAS)-x%(w/w) Li2O-Na2O-B2O3-SiO2 (LNBS) (x=0, 1, 2, 3, 4) ceramics were prepared by solid state route. The effect of LNBS sintering aids on the microstructure and dielectric properties of BAS system ceramics were studied. Deviation between theoretical and experimental permittivity (εr) of BAS was discussed. The results showed that LNBS sintering aids could reduce the sintering temperature from 1 400 to 1 325℃, and the O2- vacancy or Ba2+ were formed by Li+ substituting for Al3+ or Li+ entering into the single four-membered-ring (S4R) to promote the transformation of hexacelsian to celsian of BAS. The density, quality factor (Qf) value, the temperature coefficient of resonant frequency (τf) of BAS-x% LNBS ceramics have been improved by adding moderate LNBS sintering aids. The BAS-1% LNBS sintered at 1 325℃ obtained well dielectric properties:Qf=35 199 GHz, εr=6.37 and τf=-1.613×10-5℃-1.
BaO-Al2O3-SiO2 (BAS)-x%(w/w) Li2O-Na2O-B2O3-SiO2 (LNBS) (x=0, 1, 2, 3, 4) ceramics were prepared by solid state route. The effect of LNBS sintering aids on the microstructure and dielectric properties of BAS system ceramics were studied. Deviation between theoretical and experimental permittivity (εr) of BAS was discussed. The results showed that LNBS sintering aids could reduce the sintering temperature from 1 400 to 1 325℃, and the O2- vacancy or Ba2+ were formed by Li+ substituting for Al3+ or Li+ entering into the single four-membered-ring (S4R) to promote the transformation of hexacelsian to celsian of BAS. The density, quality factor (Qf) value, the temperature coefficient of resonant frequency (τf) of BAS-x% LNBS ceramics have been improved by adding moderate LNBS sintering aids. The BAS-1% LNBS sintered at 1 325℃ obtained well dielectric properties:Qf=35 199 GHz, εr=6.37 and τf=-1.613×10-5℃-1.
2019, 35(8): 1363-1370
doi: 10.11862/CJIC.2019.163
Abstract:
Cobalt sulfide/porous carbon (CoS/C) composite catalysts have been synthesized through combination of ion exchange method and heat treatment method with ZIF67 as precursor and thioacetamide as sulfur source. The effect of vulcanization time on the morphology, structure and oxygen reduction (ORR) performance of the composite catalyst were discussed. The morphology and structure of the composite catalyst were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 adsorption-desorption measurement, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman) and rotating disk electrode (RDE) techniques. The results showed that the composite catalyst had the comparable ORR activity to commercial 20%(w/w) Pt/C catalyst in alkaline medium, and its half-wave potential was negative to the Pt/C catalyst only 31 mV. With the increase of vulcanization time, the cobalt sulfide particles gradually increased, and the degree of disorder of carbon materials in the catalyst first decreased and then increased. When the vulcanization time was 10 min, the composite catalyst showed the best ORR performance in alkaline medium (0.1 mol·L-1 KOH). The average number of transferred electrons in the ORR process could reach 3.72, close to 4, indicating that the ORR was a four electronic transfer process on the surface of the catalyst.
Cobalt sulfide/porous carbon (CoS/C) composite catalysts have been synthesized through combination of ion exchange method and heat treatment method with ZIF67 as precursor and thioacetamide as sulfur source. The effect of vulcanization time on the morphology, structure and oxygen reduction (ORR) performance of the composite catalyst were discussed. The morphology and structure of the composite catalyst were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 adsorption-desorption measurement, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman) and rotating disk electrode (RDE) techniques. The results showed that the composite catalyst had the comparable ORR activity to commercial 20%(w/w) Pt/C catalyst in alkaline medium, and its half-wave potential was negative to the Pt/C catalyst only 31 mV. With the increase of vulcanization time, the cobalt sulfide particles gradually increased, and the degree of disorder of carbon materials in the catalyst first decreased and then increased. When the vulcanization time was 10 min, the composite catalyst showed the best ORR performance in alkaline medium (0.1 mol·L-1 KOH). The average number of transferred electrons in the ORR process could reach 3.72, close to 4, indicating that the ORR was a four electronic transfer process on the surface of the catalyst.
2019, 35(8): 1371-1378
doi: 10.11862/CJIC.2019.187
Abstract:
By employing electrospun TiO2 nanofiber as substrate, Bi@Bi2Sn2O7/TiO2 plasmonic composite fibers were prepared via one-step hydrothermal method. The composition, morphology and optical properties were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), ultraviolet-visible diffuse reflection spectra (UV-Vis DRS) and photoluminescence spectroscopy (PL) analysis. The photocatalytic water splitting for hydrogen evolution was investigated over Bi@Bi2Sn2O7/TiO2 plasmonic composite fibers with triethanolamine as the donor residue. The results showed that the Bi nanoparticles were generated onto Bi2Sn2O7 nanoparticle via the in situ reduction of Bi3+ by glucose, meanwhile grew on the TiO2 nanofibers surface. The enhanced photocatalytic activity of the Bi@Bi2Sn2O7/TiO2 plasmonic composites fibers can be further improved mainly attributed to the formation of high-quality p-n heterojunctions between Bi2Sn2O7 and titanium dioxide, the plasma resonance effect of metal bismuth, and the synergistic effect of plasma resonance effect and p-n heterojunction. The corresponding H2 production rate was 7.26 mmol·h-1·g-1.
By employing electrospun TiO2 nanofiber as substrate, Bi@Bi2Sn2O7/TiO2 plasmonic composite fibers were prepared via one-step hydrothermal method. The composition, morphology and optical properties were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), ultraviolet-visible diffuse reflection spectra (UV-Vis DRS) and photoluminescence spectroscopy (PL) analysis. The photocatalytic water splitting for hydrogen evolution was investigated over Bi@Bi2Sn2O7/TiO2 plasmonic composite fibers with triethanolamine as the donor residue. The results showed that the Bi nanoparticles were generated onto Bi2Sn2O7 nanoparticle via the in situ reduction of Bi3+ by glucose, meanwhile grew on the TiO2 nanofibers surface. The enhanced photocatalytic activity of the Bi@Bi2Sn2O7/TiO2 plasmonic composites fibers can be further improved mainly attributed to the formation of high-quality p-n heterojunctions between Bi2Sn2O7 and titanium dioxide, the plasma resonance effect of metal bismuth, and the synergistic effect of plasma resonance effect and p-n heterojunction. The corresponding H2 production rate was 7.26 mmol·h-1·g-1.
2019, 35(8): 1379-1386
doi: 10.11862/CJIC.2019.168
Abstract:
Amino-functionalized Fe3O4 magnetic material (NH2@nFe3O4) was prepared via a solvothermal method, followed by impregnation with Al(Ⅲ) phthalocyanine sulfonate (AlPcS). The characterization of material with Fourier transform infrared spectroscopy, diffuse reflectance, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and vibrating magnetometer show that AlPcS mainly combines with NH2@nFe3O4 through electrostatic interaction. The average particle size and saturation magnetization of AlPcS-NH2@nFe3O4 were 127 nm, and 75.3 emu·g-1, respectively. Under visible light and air, this functionalized magnetic material has high photosensitization activity for degradation of bisphenol A (BPA), an environmental endocrine disruptor in weak alkaline aqueous solution. The photosensitization activity of composite changed with the content of AlPcS, and 3.4%(w/w) AlPcS-NH2@nFe3O4 showed the best photosensitization activity. After 60 min of reaction, the degradation rate of 20.0 mg·L-1 BPA was up to 96%, and it still remained above 93% after ten-repeated use. The reaction mechanism was discussed by NaN3 quenching experiment. It is confirmed that 1O2 is the main active species in the photosensitization process.
Amino-functionalized Fe3O4 magnetic material (NH2@nFe3O4) was prepared via a solvothermal method, followed by impregnation with Al(Ⅲ) phthalocyanine sulfonate (AlPcS). The characterization of material with Fourier transform infrared spectroscopy, diffuse reflectance, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and vibrating magnetometer show that AlPcS mainly combines with NH2@nFe3O4 through electrostatic interaction. The average particle size and saturation magnetization of AlPcS-NH2@nFe3O4 were 127 nm, and 75.3 emu·g-1, respectively. Under visible light and air, this functionalized magnetic material has high photosensitization activity for degradation of bisphenol A (BPA), an environmental endocrine disruptor in weak alkaline aqueous solution. The photosensitization activity of composite changed with the content of AlPcS, and 3.4%(w/w) AlPcS-NH2@nFe3O4 showed the best photosensitization activity. After 60 min of reaction, the degradation rate of 20.0 mg·L-1 BPA was up to 96%, and it still remained above 93% after ten-repeated use. The reaction mechanism was discussed by NaN3 quenching experiment. It is confirmed that 1O2 is the main active species in the photosensitization process.
2019, 35(8): 1387-1395
doi: 10.11862/CJIC.2019.183
Abstract:
Cu2O was synthesized by chemical precipitation, La doped BaTiO3-based powders were synthesized via a hydrothermal method using the Cu2O as the sacrifice template. The structure, morphology and visible light properties have been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscope (HR-TEM), X-ray photoelectron spectroscopy (XPS), scanning electron micro-graphs (SEM), UV-Vis diffuse reflectance spectrophotometer (UV-Vis DRS). The results showed that the doping of La3+ increased the conductivity and made the range of photo-response broadened, which reduced the band gap of the semiconductor and accelerated the separation of photo-generated electron hole pairs. The surface defects were induced with a facile and effective approach by La3+ ion doping, and the photocatalytic performance of BaTiO3 was improved. However, as the doping amount of La3+ ions increased, the band gap of the semiconductors decreased and the redox ability of the phototgenerated electrons and holes deceased when the dopant was excessive. When the doping amount was 4%(w/w), the photocatalytic performance of the sample was the best, and the degradation efficiency of 4-nitrophenol was 93.2% after 360 min visible light irradiation. The decomposition rate of 4-nitrophenol was still above 86.7% even after 5 cycles, thus artificial catalytic defects of La donor-doped BaTiO3-based nanoparticle could effectively improve the photocatalytic properties.
Cu2O was synthesized by chemical precipitation, La doped BaTiO3-based powders were synthesized via a hydrothermal method using the Cu2O as the sacrifice template. The structure, morphology and visible light properties have been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscope (HR-TEM), X-ray photoelectron spectroscopy (XPS), scanning electron micro-graphs (SEM), UV-Vis diffuse reflectance spectrophotometer (UV-Vis DRS). The results showed that the doping of La3+ increased the conductivity and made the range of photo-response broadened, which reduced the band gap of the semiconductor and accelerated the separation of photo-generated electron hole pairs. The surface defects were induced with a facile and effective approach by La3+ ion doping, and the photocatalytic performance of BaTiO3 was improved. However, as the doping amount of La3+ ions increased, the band gap of the semiconductors decreased and the redox ability of the phototgenerated electrons and holes deceased when the dopant was excessive. When the doping amount was 4%(w/w), the photocatalytic performance of the sample was the best, and the degradation efficiency of 4-nitrophenol was 93.2% after 360 min visible light irradiation. The decomposition rate of 4-nitrophenol was still above 86.7% even after 5 cycles, thus artificial catalytic defects of La donor-doped BaTiO3-based nanoparticle could effectively improve the photocatalytic properties.
2019, 35(8): 1396-1402
doi: 10.11862/CJIC.2019.145
Abstract:
The alkylation of isobutane/butene is an important reaction to produce high-octane gasoline. Replacement of liquid acid by solid acid to catalyze this reaction is the focus of the study. In this work, solid acid catalysts with hydrophobic surface were prepared by decorating hexadecylphosphate (HDPA) on SiO2-supported heteropolyacids samples with impregnatiom method, whose structure is similar as the fruit of platanus. These catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), N2 and i-C4H10 sorption. And the performances of the catalysts for the alkylation of isobutane/butene were evaluated using a fixed bed micro-reactor. The results show that the HDPA-modification enhances the adsorption of the hydrocarbon reactants on the surface of catalyst, which helps to reduce the polymerization of butene and to inhibit the deposition of coke on the surface of catalyst, leading to an improved selectivity of high-octane products and prolonged life of catalysts. The catalyst had an optimal catalytic performance when the HPW load was 30%(w/w) and the modified amount of HDPA is 3%(w/w).
The alkylation of isobutane/butene is an important reaction to produce high-octane gasoline. Replacement of liquid acid by solid acid to catalyze this reaction is the focus of the study. In this work, solid acid catalysts with hydrophobic surface were prepared by decorating hexadecylphosphate (HDPA) on SiO2-supported heteropolyacids samples with impregnatiom method, whose structure is similar as the fruit of platanus. These catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), N2 and i-C4H10 sorption. And the performances of the catalysts for the alkylation of isobutane/butene were evaluated using a fixed bed micro-reactor. The results show that the HDPA-modification enhances the adsorption of the hydrocarbon reactants on the surface of catalyst, which helps to reduce the polymerization of butene and to inhibit the deposition of coke on the surface of catalyst, leading to an improved selectivity of high-octane products and prolonged life of catalysts. The catalyst had an optimal catalytic performance when the HPW load was 30%(w/w) and the modified amount of HDPA is 3%(w/w).
2019, 35(8): 1403-1410
doi: 10.11862/CJIC.2019.177
Abstract:
Manganese-doped Ni1-xMnx(OH)2 (x=0.1, 0.2, 0.3, 0.4) was prepared by buffer solution method. X-ray diffraction (XRD) measurements showed that the samples were mainly composed of β phase when x=0.1 and 0.2. Scanning electron microscopy (SEM) measurements and nitrogen adsorption-desorption showed that the Mn doped samples were finer and more porous than commercial β-Ni(OH)2 samples without Mn. The constant current charge-discharge tests show that the material of Ni0.8Mn0.2(OH)2 exhibited a high specific discharge capacity of 288.8 mAh·g-1 at 800 mA·g-1 when the specific discharge capacity of commercial β-Ni(OH)2 was 198.7 mAh·g-1. In addition, the electrodes have excellent cycle performance. When the Mn content x is 0.2, the material maintained a specific discharge capacity of 276 mAh·g-1 after circulating 580 cycles at 800 mA·g-1 with an attenuation rate of 4.1%, the attenuation rates of the others were 46.1% (commercial β-Ni(OH)2), 13.0% (x=0.1), 22.6% (x=0.3) and 34.1% (x=0.4). This indicated that Mn doped Ni(OH)2 can improve the cycling stability of nickel electrodes at high current density, and greatly reduce the cost of nickel electrodes.
Manganese-doped Ni1-xMnx(OH)2 (x=0.1, 0.2, 0.3, 0.4) was prepared by buffer solution method. X-ray diffraction (XRD) measurements showed that the samples were mainly composed of β phase when x=0.1 and 0.2. Scanning electron microscopy (SEM) measurements and nitrogen adsorption-desorption showed that the Mn doped samples were finer and more porous than commercial β-Ni(OH)2 samples without Mn. The constant current charge-discharge tests show that the material of Ni0.8Mn0.2(OH)2 exhibited a high specific discharge capacity of 288.8 mAh·g-1 at 800 mA·g-1 when the specific discharge capacity of commercial β-Ni(OH)2 was 198.7 mAh·g-1. In addition, the electrodes have excellent cycle performance. When the Mn content x is 0.2, the material maintained a specific discharge capacity of 276 mAh·g-1 after circulating 580 cycles at 800 mA·g-1 with an attenuation rate of 4.1%, the attenuation rates of the others were 46.1% (commercial β-Ni(OH)2), 13.0% (x=0.1), 22.6% (x=0.3) and 34.1% (x=0.4). This indicated that Mn doped Ni(OH)2 can improve the cycling stability of nickel electrodes at high current density, and greatly reduce the cost of nickel electrodes.
2019, 35(8): 1411-1418
doi: 10.11862/CJIC.2019.171
Abstract:
A novel easily-scalable "top-down" method was used to prepare graphite cathode materials with chara-cteristics of few layers, small size and defect-free, which further increases the embedding sites of ions and breaks the inherent capacity limitation of graphite, so as to improve the electrochemical performance of aluminum ion batteries. Scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD) were used to characterize the properties of graphite materials, indicating that the proposed "top-down" method is able to realize the stripping of graphite without destroying the structure and achieve effective control of the thickness and size of graphite layer by adjusting the ball milling time. Electrochemical test results showed that the discharge capacities of G-48 reached 93 mAh·g-1 under a current density of 3C and still retained 68 mAh·g-1 under a high current density of 10C with excellent cycling performance. In addition, the preparation process is simple and low cost, which provides a good foundation for promoting the commercial application of the high-capacity and long-life aluminum ion batteries.
A novel easily-scalable "top-down" method was used to prepare graphite cathode materials with chara-cteristics of few layers, small size and defect-free, which further increases the embedding sites of ions and breaks the inherent capacity limitation of graphite, so as to improve the electrochemical performance of aluminum ion batteries. Scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD) were used to characterize the properties of graphite materials, indicating that the proposed "top-down" method is able to realize the stripping of graphite without destroying the structure and achieve effective control of the thickness and size of graphite layer by adjusting the ball milling time. Electrochemical test results showed that the discharge capacities of G-48 reached 93 mAh·g-1 under a current density of 3C and still retained 68 mAh·g-1 under a high current density of 10C with excellent cycling performance. In addition, the preparation process is simple and low cost, which provides a good foundation for promoting the commercial application of the high-capacity and long-life aluminum ion batteries.
2019, 35(8): 1419-1426
doi: 10.11862/CJIC.2019.185
Abstract:
The NiCo2S4@carbon nanotube (CNT) constructed flexible film(NiCo2S4@CNTF)electrodes was synthes-ized by a new top-down route using dense and ultrathin carbon nanotube films (CNTF)from floating catalytic chemical vapor deposition as a support. The synthesis included two-step acid treatment of a dense-packed CNTF leading to a three-dimensionally porous conductive matrix, growth of uniformNiCo2(CO3)1.5(OH)3 precursor on each CNT, followed by solution-based sulfidation. Meanwhile the two-step acid treatment transformed hydrophobic CNTF to be highly hydrophilic, which made its interior to be highly ion-accessible and well-separation of adjacent CNTs in a 3D space, thus assured high loadings. The products were characterized by X-ray diffraction, scanning electron microscopy and other techniques. The results indicatedthat the optimal products were flexible composite filmswith a 3D network structure constructed by NiCo2S4 coated CNTs. The NiCo2S4 nanoparticle coating was rough with a thickness of~70 nm, which is benefit for providing active sites for electrochemical energy storage. The composite film electrode had a specific capacitance of 270.3 mF·cm-2 at 0.5 mA·cm-2, and exhibited excellent cycling stability with 93% of initial capacitance even after 10 000 cycles at a high current density of 2.5 mA·cm-2. The coulombic efficiency kept at around 92% with fluctuations during the whole cycling. Also, the composite film electrode kept good structure integrity after repeated large deformations. The relationship been the specific nanostructure and electrochemical performance was discussed in detail, and involved mechanism was also revealed.
The NiCo2S4@carbon nanotube (CNT) constructed flexible film(NiCo2S4@CNTF)electrodes was synthes-ized by a new top-down route using dense and ultrathin carbon nanotube films (CNTF)from floating catalytic chemical vapor deposition as a support. The synthesis included two-step acid treatment of a dense-packed CNTF leading to a three-dimensionally porous conductive matrix, growth of uniformNiCo2(CO3)1.5(OH)3 precursor on each CNT, followed by solution-based sulfidation. Meanwhile the two-step acid treatment transformed hydrophobic CNTF to be highly hydrophilic, which made its interior to be highly ion-accessible and well-separation of adjacent CNTs in a 3D space, thus assured high loadings. The products were characterized by X-ray diffraction, scanning electron microscopy and other techniques. The results indicatedthat the optimal products were flexible composite filmswith a 3D network structure constructed by NiCo2S4 coated CNTs. The NiCo2S4 nanoparticle coating was rough with a thickness of~70 nm, which is benefit for providing active sites for electrochemical energy storage. The composite film electrode had a specific capacitance of 270.3 mF·cm-2 at 0.5 mA·cm-2, and exhibited excellent cycling stability with 93% of initial capacitance even after 10 000 cycles at a high current density of 2.5 mA·cm-2. The coulombic efficiency kept at around 92% with fluctuations during the whole cycling. Also, the composite film electrode kept good structure integrity after repeated large deformations. The relationship been the specific nanostructure and electrochemical performance was discussed in detail, and involved mechanism was also revealed.
