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2025 Volume 41 Issue 4
2025, 41(4):
Abstract:
2025, 41(4): 100030
doi: 10.3866/PKU.WHXB202309045
Abstract:
Metal halide perovskites show immense promise in photodetection applications, having been employed in the research of photodiodes, photoconductors, and phototransistors. However, the majority of current photodetectors utilizing perovskite materials rely on polycrystalline thin films, and the presence of grain boundaries and defects hinders their photoelectric performance, creating a bottleneck in further advancements. To address this issue, researchers have employed techniques such as inverse temperature crystallization (ITC) and anti-solvent vapor-assisted crystallization (AVC) to synthesize various perovskite single crystals. Bulk single crystal perovskite structures are advantageous due to their lack of grain boundaries, resulting in lower dark current and noise in photodetectors, thereby enhancing their weak light detection capabilities. Additionally, the diminished presence of grain boundaries extends the lifetime of photo-generated carriers, providing a foundation for improved detector performance. However, due to the excellent optical absorption coefficient of perovskites, the excessive thickness of bulk single crystals can only increase the probability of carrier recombination, impacting the photodetector’s performance. Consequently, perovskite thin single crystal materials prepared by controlling longitudinal size have garnered significant interest in novel detector research. Various techniques, such as space-confined method, surface tension-assisted method, and vapor phase epitaxy, have been proposed to growth thin single crystals with controllable thickness. These methods have been continually optimized to enhance crystal quality. Thin single crystal perovskites not only enhance photodetector performance but also hold potential for large-area single crystal production, supporting the development of photodetector imaging arrays. This paper outlines the fundamental principles behind perovskite single crystal growth, introduces various technological approaches developed for thin perovskite single crystal growth, and analyzes the resulting materials from different growth methods. It further reviews notable studies in the realm of perovskite thin single crystal photodetectors for different device types. Finally, the paper discusses current challenges and issues in this field while offering insights into potential future directions of development.
Metal halide perovskites show immense promise in photodetection applications, having been employed in the research of photodiodes, photoconductors, and phototransistors. However, the majority of current photodetectors utilizing perovskite materials rely on polycrystalline thin films, and the presence of grain boundaries and defects hinders their photoelectric performance, creating a bottleneck in further advancements. To address this issue, researchers have employed techniques such as inverse temperature crystallization (ITC) and anti-solvent vapor-assisted crystallization (AVC) to synthesize various perovskite single crystals. Bulk single crystal perovskite structures are advantageous due to their lack of grain boundaries, resulting in lower dark current and noise in photodetectors, thereby enhancing their weak light detection capabilities. Additionally, the diminished presence of grain boundaries extends the lifetime of photo-generated carriers, providing a foundation for improved detector performance. However, due to the excellent optical absorption coefficient of perovskites, the excessive thickness of bulk single crystals can only increase the probability of carrier recombination, impacting the photodetector’s performance. Consequently, perovskite thin single crystal materials prepared by controlling longitudinal size have garnered significant interest in novel detector research. Various techniques, such as space-confined method, surface tension-assisted method, and vapor phase epitaxy, have been proposed to growth thin single crystals with controllable thickness. These methods have been continually optimized to enhance crystal quality. Thin single crystal perovskites not only enhance photodetector performance but also hold potential for large-area single crystal production, supporting the development of photodetector imaging arrays. This paper outlines the fundamental principles behind perovskite single crystal growth, introduces various technological approaches developed for thin perovskite single crystal growth, and analyzes the resulting materials from different growth methods. It further reviews notable studies in the realm of perovskite thin single crystal photodetectors for different device types. Finally, the paper discusses current challenges and issues in this field while offering insights into potential future directions of development.
2025, 41(4): 100032
doi: 10.3866/PKU.WHXB202404006
Abstract:
Uranium is an indispensable resource for the nuclear industry, while land-based uranium mines are limited in content and unevenly distributed. Therefore, uranium extraction from seawater (UES) holds great potential for sustainable energy production. Capacitive deionization (CDI) technology, known for its low energy consumption, simple process, environmentally friendliness, and high adsorption efficiency, holds significant potential for UES. This paper reviews the development history, principles, classifications, and applications of CDI technology. In the section on development history, we provide a brief overview of the early development of CDI technology, emphasizing key milestones in its application to UES and recent optimization efforts. In the section on principle and categorization, we contextualize CDI technology within UES applications for a comprehensive introduction. Additionally, in the application section, we concentrate on current applications of CDI technology in UES. Furthermore, this paper elaborates on the current research status of CDI for UES and its advantages in terms of adsorptivity, selectivity, and economic benefits. In terms of adsorptivity, CDI technology demonstrates its efficiency in adsorbing uranium ions, achieved through meticulous optimization of electrode structure and material selection. With regard to selectivity, CDI technology selectively extracts uranium while mitigating interference from competing ions through adept modulation of electrode materials and operational parameters, thereby enhancing extraction efficiency. Economically, CDI technology stands out due to its hallmark features of low energy consumption and cost-effectiveness, facilitating high-efficiency uranium extraction and providing substantial economic advantages over alternative methods in the UES domain. Lastly, we discuss the challenge factors (competing ions, salinity, pH, and biofouling) of this technology in the uranium extraction process, aiming to explore the feasibility and economic benefits of UES by using the CDI technology and providing theoretical support for further optimization and promotion of CDI applications in UES. Additionally, we aim to address some of the current challenges of uranium extraction using CDI by incorporating materials informatics and providing an outlook on this matter. This paper provides practical insights into the development and industrial progress of CDI technology in UES, aiming to offer valuable references for the subsequent research on CDI seawater uranium extraction to contribute to the sustainable utilization of seawater resources.
Uranium is an indispensable resource for the nuclear industry, while land-based uranium mines are limited in content and unevenly distributed. Therefore, uranium extraction from seawater (UES) holds great potential for sustainable energy production. Capacitive deionization (CDI) technology, known for its low energy consumption, simple process, environmentally friendliness, and high adsorption efficiency, holds significant potential for UES. This paper reviews the development history, principles, classifications, and applications of CDI technology. In the section on development history, we provide a brief overview of the early development of CDI technology, emphasizing key milestones in its application to UES and recent optimization efforts. In the section on principle and categorization, we contextualize CDI technology within UES applications for a comprehensive introduction. Additionally, in the application section, we concentrate on current applications of CDI technology in UES. Furthermore, this paper elaborates on the current research status of CDI for UES and its advantages in terms of adsorptivity, selectivity, and economic benefits. In terms of adsorptivity, CDI technology demonstrates its efficiency in adsorbing uranium ions, achieved through meticulous optimization of electrode structure and material selection. With regard to selectivity, CDI technology selectively extracts uranium while mitigating interference from competing ions through adept modulation of electrode materials and operational parameters, thereby enhancing extraction efficiency. Economically, CDI technology stands out due to its hallmark features of low energy consumption and cost-effectiveness, facilitating high-efficiency uranium extraction and providing substantial economic advantages over alternative methods in the UES domain. Lastly, we discuss the challenge factors (competing ions, salinity, pH, and biofouling) of this technology in the uranium extraction process, aiming to explore the feasibility and economic benefits of UES by using the CDI technology and providing theoretical support for further optimization and promotion of CDI applications in UES. Additionally, we aim to address some of the current challenges of uranium extraction using CDI by incorporating materials informatics and providing an outlook on this matter. This paper provides practical insights into the development and industrial progress of CDI technology in UES, aiming to offer valuable references for the subsequent research on CDI seawater uranium extraction to contribute to the sustainable utilization of seawater resources.
2025, 41(4): 100035
doi: 10.3866/PKU.WHXB202406014
Abstract:
Sodium ion batteries, due to their abundant resources, low raw material costs, excellent performance in low-temperature conditions, and fast charging capabilities, offer promising prospects for power grid energy storage and low-speed transportation. They serve as a complementary alternative to lithium-ion batteries. The cathode material is crucial for overall battery performance, acting as a bottleneck for enhancing the specific energy of sodium-ion batteries and a significant factor influencing costs. Low-cost iron-based polyanionic cathode materials have garnered attention in basic research and industrialization due to their inherent advantages: excellent structural stability, high safety levels, and minimal volume strain during charge-discharge cycles. These advantages are pivotal for practical implementations in electric vehicles, large-scale energy storage systems, portable electronics, and related applications. However, challenges such as capacity decay and structural stability during prolonged cycling may limit their industrial applicability. Therefore, enhancing material cycling life and battery system stability are critical concerns. Additionally, researchers are focused on discovering new iron-based polyanion cathode materials with high specific capacity, operating voltage, and conductivity. This review comprehensively covers recent advancements in iron-based polyanionic cathode materials for sodium-ion batteries, encompassing iron-based phosphates, fluorophosphates, pyrophosphates, sulfates, and mixed polyanionic compounds. The analysis systematically explores crystal structures, preparation methods, sodium storage mechanisms, and modification strategies for various iron-based polyanionic materials, elucidating the structure-activity relationship between chemical composition, structural regulation techniques, and performance enhancement. Moreover, the article discusses challenges encountered during the transition from laboratory-scale research to large-scale industrial applications of iron-based polyanion cathode materials, along with corresponding solutions. These insights aim to offer theoretical and technical guidance for developing novel, low-cost cathode materials with high specific energy densities and advancing the industrialization of sodium-ion batteries.
Sodium ion batteries, due to their abundant resources, low raw material costs, excellent performance in low-temperature conditions, and fast charging capabilities, offer promising prospects for power grid energy storage and low-speed transportation. They serve as a complementary alternative to lithium-ion batteries. The cathode material is crucial for overall battery performance, acting as a bottleneck for enhancing the specific energy of sodium-ion batteries and a significant factor influencing costs. Low-cost iron-based polyanionic cathode materials have garnered attention in basic research and industrialization due to their inherent advantages: excellent structural stability, high safety levels, and minimal volume strain during charge-discharge cycles. These advantages are pivotal for practical implementations in electric vehicles, large-scale energy storage systems, portable electronics, and related applications. However, challenges such as capacity decay and structural stability during prolonged cycling may limit their industrial applicability. Therefore, enhancing material cycling life and battery system stability are critical concerns. Additionally, researchers are focused on discovering new iron-based polyanion cathode materials with high specific capacity, operating voltage, and conductivity. This review comprehensively covers recent advancements in iron-based polyanionic cathode materials for sodium-ion batteries, encompassing iron-based phosphates, fluorophosphates, pyrophosphates, sulfates, and mixed polyanionic compounds. The analysis systematically explores crystal structures, preparation methods, sodium storage mechanisms, and modification strategies for various iron-based polyanionic materials, elucidating the structure-activity relationship between chemical composition, structural regulation techniques, and performance enhancement. Moreover, the article discusses challenges encountered during the transition from laboratory-scale research to large-scale industrial applications of iron-based polyanion cathode materials, along with corresponding solutions. These insights aim to offer theoretical and technical guidance for developing novel, low-cost cathode materials with high specific energy densities and advancing the industrialization of sodium-ion batteries.
2025, 41(4): 100031
doi: 10.3866/PKU.WHXB202402016
Abstract:
Against the backdrop of energy scarcities and ecological concerns, the process of photocatalytic hydrogen evolution emerges as a critical method for transforming solar energy into chemical energy. Central to this technology is the crafting of photocatalysts that are not only efficient and durable but also economically viable. The key to creating photocatalysts that boast superior hydrogen production capabilities lies in enhancing the separation and transfer of photo-generated electrons and holes. This study introduces a binary heterojunction photocatalyst, featuring a combination of Cd0.5Zn0.5S and Ti3C2 MXene, synthesized via an in situ hydrothermal method. In the composite, slender Cd0.5Zn0.5S nanorods are uniformly coated over the surface of single layer Ti3C2 nanosheets, forming a Schottky heterojunction at the material interface. This structure enhances the separation efficiency of photo-generated electrons and holes, thereby improving the utilization of light. With 0.5 wt% (mass fraction) of Ti3C2 MXene incorporated, we observed a peak photocatalytic H2 generation rate of 15.56 mmol∙g−1∙h−1, outperforming the baseline Cd0.5Zn0.5S by 2.56 times. Notably, the photocatalytic efficiency remained largely unchanged after five cycles. This composite achieved the highest apparent quantum efficiency (AQE) of 18.4% when exposed to 350 nm UV light. Various characterization techniques, including in situ X-ray photoelectron spectroscopy (XPS) and femtosecond transient absorption (fs-TA) spectroscopy, along with density functional theory (DFT) calculations, have further substantiated that the formation of a Schottky heterojunction at the interface is crucial for enhancing the photocatalytic hydrogen evolution performance of the composite material. This paper demonstrates the effectiveness of the novel carbon based material MXene as a co-catalyst for improving the performance of photocatalysts and offers a viable approach for the construction of MXene-containing photocatalytic hydrogen evolution catalysts.
Against the backdrop of energy scarcities and ecological concerns, the process of photocatalytic hydrogen evolution emerges as a critical method for transforming solar energy into chemical energy. Central to this technology is the crafting of photocatalysts that are not only efficient and durable but also economically viable. The key to creating photocatalysts that boast superior hydrogen production capabilities lies in enhancing the separation and transfer of photo-generated electrons and holes. This study introduces a binary heterojunction photocatalyst, featuring a combination of Cd0.5Zn0.5S and Ti3C2 MXene, synthesized via an in situ hydrothermal method. In the composite, slender Cd0.5Zn0.5S nanorods are uniformly coated over the surface of single layer Ti3C2 nanosheets, forming a Schottky heterojunction at the material interface. This structure enhances the separation efficiency of photo-generated electrons and holes, thereby improving the utilization of light. With 0.5 wt% (mass fraction) of Ti3C2 MXene incorporated, we observed a peak photocatalytic H2 generation rate of 15.56 mmol∙g−1∙h−1, outperforming the baseline Cd0.5Zn0.5S by 2.56 times. Notably, the photocatalytic efficiency remained largely unchanged after five cycles. This composite achieved the highest apparent quantum efficiency (AQE) of 18.4% when exposed to 350 nm UV light. Various characterization techniques, including in situ X-ray photoelectron spectroscopy (XPS) and femtosecond transient absorption (fs-TA) spectroscopy, along with density functional theory (DFT) calculations, have further substantiated that the formation of a Schottky heterojunction at the interface is crucial for enhancing the photocatalytic hydrogen evolution performance of the composite material. This paper demonstrates the effectiveness of the novel carbon based material MXene as a co-catalyst for improving the performance of photocatalysts and offers a viable approach for the construction of MXene-containing photocatalytic hydrogen evolution catalysts.
2025, 41(4): 100033
doi: 10.3866/PKU.WHXB202404023
Abstract:
The efficient electrocatalysts towards the oxygen evolution reaction (OER) are vital for water splitting. Herein, a novel FeCoCrMnBS high-entropy (Oxy) hydroxide (HEH) is synthesized on a nickel foam (NF) surface via a facile approach. The FeCoCrMnBS HEH possesses a porous morphology composed of plentiful ultra-thin nanosheets with the amorphous structure. The obtained FeCoCrMnBS/NF electrode exhibits exceptional electrocatalytic OER activity in alkaline solution, requiring only 290 mV overpotential for 100 mA∙cm−2. Moreover, this catalyst displays a long-term durability of over 120 h at 10 mA∙cm−2. The enhanced catalytic performance benefits from the unique amorphous structure and the positive synergy effect between B and S, promoting the formation of SO42− and thus weakening the adsorption of intermediates in OER on the catalyst surface. This work provides a new strategy for the design of desirable OER electrocatalysts.
The efficient electrocatalysts towards the oxygen evolution reaction (OER) are vital for water splitting. Herein, a novel FeCoCrMnBS high-entropy (Oxy) hydroxide (HEH) is synthesized on a nickel foam (NF) surface via a facile approach. The FeCoCrMnBS HEH possesses a porous morphology composed of plentiful ultra-thin nanosheets with the amorphous structure. The obtained FeCoCrMnBS/NF electrode exhibits exceptional electrocatalytic OER activity in alkaline solution, requiring only 290 mV overpotential for 100 mA∙cm−2. Moreover, this catalyst displays a long-term durability of over 120 h at 10 mA∙cm−2. The enhanced catalytic performance benefits from the unique amorphous structure and the positive synergy effect between B and S, promoting the formation of SO42− and thus weakening the adsorption of intermediates in OER on the catalyst surface. This work provides a new strategy for the design of desirable OER electrocatalysts.
2025, 41(4): 100034
doi: 10.3866/PKU.WHXB202406012
Abstract:
Boron-containing zeolites can catalyze the oxidative dehydrogenation of propane (ODHP) to produce propylene. Enhancing the quantity of active boron-oxygen species and regulating the positioning of these species within the zeolite are the main challenges in developing efficient boron-based catalysts. In this study, a boron-containing zeolite catalyst with exposed (010) crystal facets, referred to as the MFI-type boron-containing zeolite (BMFI), was synthesized using a urea-assisted hydrothermal method. The research indicates that the addition of an appropriate amount of urea can regulate the morphology of the zeolite, with its short-axis flake-like structure enhancing the accessibility of active boron sites and anchoring a higher content of active boron-oxygen species through hydrogen bonding, which significantly improves the ODHP activity and olefin selectivity of the catalyst. The propane conversion rate reached 20%, with a propylene selectivity of 62.3% and a total olefin selectivity of 81.3% at 520 ℃. Compared to the ellipsoidal boron-containing catalyst formed without urea, the flake-like BMFI catalyst exhibited nearly a 20-fold increase in the reaction rate of propane. The flake-like BMFI possesses a greater number of framework tetrahedrally coordinated boron (B[4]) and defective boron species (B[3]a and B[3]b), and active boron structural evolution occurred during the reaction process, with B[3]a and B[3]b being the active sites for the catalytic reaction. This study provides a reference for the structural design and regulation of boron-based catalysts for the oxidative dehydrogenation of light alkanes.
Boron-containing zeolites can catalyze the oxidative dehydrogenation of propane (ODHP) to produce propylene. Enhancing the quantity of active boron-oxygen species and regulating the positioning of these species within the zeolite are the main challenges in developing efficient boron-based catalysts. In this study, a boron-containing zeolite catalyst with exposed (010) crystal facets, referred to as the MFI-type boron-containing zeolite (BMFI), was synthesized using a urea-assisted hydrothermal method. The research indicates that the addition of an appropriate amount of urea can regulate the morphology of the zeolite, with its short-axis flake-like structure enhancing the accessibility of active boron sites and anchoring a higher content of active boron-oxygen species through hydrogen bonding, which significantly improves the ODHP activity and olefin selectivity of the catalyst. The propane conversion rate reached 20%, with a propylene selectivity of 62.3% and a total olefin selectivity of 81.3% at 520 ℃. Compared to the ellipsoidal boron-containing catalyst formed without urea, the flake-like BMFI catalyst exhibited nearly a 20-fold increase in the reaction rate of propane. The flake-like BMFI possesses a greater number of framework tetrahedrally coordinated boron (B[4]) and defective boron species (B[3]a and B[3]b), and active boron structural evolution occurred during the reaction process, with B[3]a and B[3]b being the active sites for the catalytic reaction. This study provides a reference for the structural design and regulation of boron-based catalysts for the oxidative dehydrogenation of light alkanes.
2025, 41(4): 100036
doi: 10.3866/PKU.WHXB202408004
Abstract:
The strong metal-support interaction (SMSI) is a widely recognized concept in heterogeneous catalysis, known for significantly enhancing catalyst stability and potentially modulating catalytic performance. However, because the SMSI effect is generally reversible, it tends to diminish under redox conditions opposite to those used for its construction. Consequently, its application is typically limited to conditions that are the same or similar to those under which it was formed. Herein, we report the application of oxidative SMSI (O-SMSI) constructed on hydroxyapatite-supported Rh catalyst (Rh/HAP) in a reductive reaction, the hydrogenation of furfuryl alcohol. In situ diffuse reflectance infrared Fourier transform spectroscopy of CO adsorption and electron microscopy measurements reveal that high-temperature oxidation treatment at 500 ℃ induced the occurrence of O-SMSI on the Rh/HAP catalyst, accompanied by the encapsulation of Rh particles by the support. Upon the O-SMSI, the Rh species were effectively stabilized on the support surface, with significant suppression of sintering and leaching during liquid-phase reactions. As a result, the catalyst showed stable furfuryl alcohol conversion and cyclopentanone selectivity during recycling tests. Furthermore, it was found that the O-SMSI and the associated encapsulation behavior on the Rh/HAP system were only partially reversible rather than completely reversible. Even after high-temperature reduction at up to 600 ℃, a portion of the SMSI effect remains, ensuring the stability of the catalysts in reductive reactions. This discovery greatly expands the application scope of SMSI catalysts and provides a new way to prepare stable hydrogenation catalysts.
The strong metal-support interaction (SMSI) is a widely recognized concept in heterogeneous catalysis, known for significantly enhancing catalyst stability and potentially modulating catalytic performance. However, because the SMSI effect is generally reversible, it tends to diminish under redox conditions opposite to those used for its construction. Consequently, its application is typically limited to conditions that are the same or similar to those under which it was formed. Herein, we report the application of oxidative SMSI (O-SMSI) constructed on hydroxyapatite-supported Rh catalyst (Rh/HAP) in a reductive reaction, the hydrogenation of furfuryl alcohol. In situ diffuse reflectance infrared Fourier transform spectroscopy of CO adsorption and electron microscopy measurements reveal that high-temperature oxidation treatment at 500 ℃ induced the occurrence of O-SMSI on the Rh/HAP catalyst, accompanied by the encapsulation of Rh particles by the support. Upon the O-SMSI, the Rh species were effectively stabilized on the support surface, with significant suppression of sintering and leaching during liquid-phase reactions. As a result, the catalyst showed stable furfuryl alcohol conversion and cyclopentanone selectivity during recycling tests. Furthermore, it was found that the O-SMSI and the associated encapsulation behavior on the Rh/HAP system were only partially reversible rather than completely reversible. Even after high-temperature reduction at up to 600 ℃, a portion of the SMSI effect remains, ensuring the stability of the catalysts in reductive reactions. This discovery greatly expands the application scope of SMSI catalysts and provides a new way to prepare stable hydrogenation catalysts.
2025, 41(4): 100037
doi: 10.3866/PKU.WHXB202408007
Abstract:
5 V-class LiNi0.5Mn1.5O4 (LNMO) cathode material is emerging as a promising cobalt-free alternative to meet the growing demand for affordable, high-performance lithium-ion batteries (LIBs). However, LNMO faces significant electrochemical challenges, particularly interfacial instability with commercial electrolytes due to its high operating potentials. This instability leads to the dissolution of transition metals and consequently electrode crosstalk, which severely deteriorates electrochemical performance. Surface coating is extensively investigated to reduce interfacial side reactions for enhanced cycling stability. Traditional methods typically require multiple steps, including dispersion, mixing, drying, and calcination, which can be time-consuming and complex. Additionally, the resulting ceramic coatings are often rigid and unevenly distributed due to lattice mismatches, potentially leading to poor interfacial contact and increased resistance. In this study, tetraethyl orthosilicate (TEOS) is proposed as a streamlined slurry additive to in situ form an ethoxy-functional polysiloxane (EPS) film on the surface of LNMO particles during electrode preparation. Post-mortem X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma (ICP) analyses reveal the crucial role of the EPS film in addressing interfacial instability issues. First, the EPS film serves as an artificial cathode-electrolyte interface (CEI) with a robust Si―O―Si bonding network, which is less vulnerable under high potentials. Second, the remaining ethoxy-functional groups in EPS scavenge HF by forming stable Si―F bonds, thereby suppressing the detrimental transition metal dissolution and crosstalk. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) further confirm the stability of the EPS film and the enhanced structural stability of the modified LNMO. Galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) results demonstrate that EPS reduces the overall impedance and improves ion diffusion kinetics by forming stable electrode-electrolyte interfaces. As a result, compared to the baseline, the optimized LNMO cathode exhibits significantly improved cycling stability in both half cells (84.6% vs. 51.4% capacity retention after 1000 cycles) and full cells when paired with commercial graphite anodes (83.3% vs. 53.4% retention after 500 cycles). This strategy, further validated under elevated temperatures of 50 ℃ and in pouch-type cells, is expected to pave the way for the development of next-generation high-performance LIBs.
5 V-class LiNi0.5Mn1.5O4 (LNMO) cathode material is emerging as a promising cobalt-free alternative to meet the growing demand for affordable, high-performance lithium-ion batteries (LIBs). However, LNMO faces significant electrochemical challenges, particularly interfacial instability with commercial electrolytes due to its high operating potentials. This instability leads to the dissolution of transition metals and consequently electrode crosstalk, which severely deteriorates electrochemical performance. Surface coating is extensively investigated to reduce interfacial side reactions for enhanced cycling stability. Traditional methods typically require multiple steps, including dispersion, mixing, drying, and calcination, which can be time-consuming and complex. Additionally, the resulting ceramic coatings are often rigid and unevenly distributed due to lattice mismatches, potentially leading to poor interfacial contact and increased resistance. In this study, tetraethyl orthosilicate (TEOS) is proposed as a streamlined slurry additive to in situ form an ethoxy-functional polysiloxane (EPS) film on the surface of LNMO particles during electrode preparation. Post-mortem X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma (ICP) analyses reveal the crucial role of the EPS film in addressing interfacial instability issues. First, the EPS film serves as an artificial cathode-electrolyte interface (CEI) with a robust Si―O―Si bonding network, which is less vulnerable under high potentials. Second, the remaining ethoxy-functional groups in EPS scavenge HF by forming stable Si―F bonds, thereby suppressing the detrimental transition metal dissolution and crosstalk. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) further confirm the stability of the EPS film and the enhanced structural stability of the modified LNMO. Galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) results demonstrate that EPS reduces the overall impedance and improves ion diffusion kinetics by forming stable electrode-electrolyte interfaces. As a result, compared to the baseline, the optimized LNMO cathode exhibits significantly improved cycling stability in both half cells (84.6% vs. 51.4% capacity retention after 1000 cycles) and full cells when paired with commercial graphite anodes (83.3% vs. 53.4% retention after 500 cycles). This strategy, further validated under elevated temperatures of 50 ℃ and in pouch-type cells, is expected to pave the way for the development of next-generation high-performance LIBs.
2025, 41(4): 100038
doi: 10.3866/PKU.WHXB202408015
Abstract:
Direct epoxidation of propylene (DEP) by molecular oxygen is an ideal way to synthesize propylene oxide (PO), yet it remains quite challenging. We demonstrated here that the PO formation rate and selectivity could be enhanced simultaneously through photo-thermo-catalysis over the Cu/TiO2 catalyst. At 180 ℃, by introducing light, the PO formation rate increased more than 20-fold (from 8.2 to 180.6 μmol∙g−1∙h−1) and the corresponding selectivity improved more than 3-fold (from 8% to 27%), breaking the traditional perception that the semiconductors exhibit very low reactivity for this reaction. Kinetic study results showed that the apparent activation energy for PO formation could sharply decrease under light irradiation (from 95 to 40 kJ∙mol−1). In situ electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were applied to characterize the dynamics of the valence state of the copper oxide species and the activation intermediates of molecular oxygen. Evidence for the activation of oxygen, which could direct to the PO formation pathway, was captured. The light-driven electrons could promote the formation of active Cu+, which could form the side-on μ-peroxo Cu(II)2 structure, weaken the O―O bond, and improve the PO formation rate and selectivity. This work paves a new way for designing semiconductor-supported photocatalysts for DEP reactions with molecular oxygen.
Direct epoxidation of propylene (DEP) by molecular oxygen is an ideal way to synthesize propylene oxide (PO), yet it remains quite challenging. We demonstrated here that the PO formation rate and selectivity could be enhanced simultaneously through photo-thermo-catalysis over the Cu/TiO2 catalyst. At 180 ℃, by introducing light, the PO formation rate increased more than 20-fold (from 8.2 to 180.6 μmol∙g−1∙h−1) and the corresponding selectivity improved more than 3-fold (from 8% to 27%), breaking the traditional perception that the semiconductors exhibit very low reactivity for this reaction. Kinetic study results showed that the apparent activation energy for PO formation could sharply decrease under light irradiation (from 95 to 40 kJ∙mol−1). In situ electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were applied to characterize the dynamics of the valence state of the copper oxide species and the activation intermediates of molecular oxygen. Evidence for the activation of oxygen, which could direct to the PO formation pathway, was captured. The light-driven electrons could promote the formation of active Cu+, which could form the side-on μ-peroxo Cu(II)2 structure, weaken the O―O bond, and improve the PO formation rate and selectivity. This work paves a new way for designing semiconductor-supported photocatalysts for DEP reactions with molecular oxygen.
