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The Chinese Journal of Structural Chemistry, founded in 1982 by Prof. Jiaxi Lu, is an international peer-reviewed journal published in English. It publishes original research works about the structure and property of matter, including but not limited to coordination chemistry, organometallic chemistry, catalysis, energy, nanomaterial, theory/computation, structural characterization, pharmacy and life science. Published monthly by Fujian Institute of Research on the Structure of Matter, CAS, in the form of Articles, Communications, Reviews, Perspectives, and News & Views. The journal is published twelve issues a year by Fujian Institute of Research on the Structure of Matter, CAS and is available online:
https://www.sciencedirect.com/journal/chinese-journal-of-structural-chemistry
Contact information：
E-mail: cjsc@fjirsm.ac.cn; Tel: +86-591-63173769
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2026, 45(9): 100966
doi: 10.1016/j.cjsc.2026.100966
Abstract:
We investigated Ni3FeN under high pressure through in situ synchrotron X-ray diffraction and resistance measurements. An irreversible structural phase transition from Pm-3m to Cmcm was observed at approximately 16.0 GPa. The transition is driven by the displacement of Fe along the b-axis and the pronounced tilting and distortion of NNi6 octahedra along the c-axis, which breaks the original cubic symmetry. This structural change leads to a significant softening of the mechanical properties, as evidenced by a more than 40% reduction in the bulk modulus (from 249.8(2) to 150.4(5) GPa) and an increase in average Ni–N bond length. Bond angle variance Bond angle variance and quadratic elongation are determined to validate distortions in NNi6 octahedron. Concurrently, analysis of the resistance-temperature (R-T) dependence reveals a crossover in scattering mechanisms, where the distorted octahedral network severely impedes electron conduction, resulting in an anomalous rise in resistance near the transition pressure, particularly at low temperatures. These findings extended the modification of structure and physical properties of Ni3FeN to high-pressure region, and laid foundation for future material design and applications in antiperovskites.
We investigated Ni3FeN under high pressure through in situ synchrotron X-ray diffraction and resistance measurements. An irreversible structural phase transition from Pm-3m to Cmcm was observed at approximately 16.0 GPa. The transition is driven by the displacement of Fe along the b-axis and the pronounced tilting and distortion of NNi6 octahedra along the c-axis, which breaks the original cubic symmetry. This structural change leads to a significant softening of the mechanical properties, as evidenced by a more than 40% reduction in the bulk modulus (from 249.8(2) to 150.4(5) GPa) and an increase in average Ni–N bond length. Bond angle variance Bond angle variance and quadratic elongation are determined to validate distortions in NNi6 octahedron. Concurrently, analysis of the resistance-temperature (R-T) dependence reveals a crossover in scattering mechanisms, where the distorted octahedral network severely impedes electron conduction, resulting in an anomalous rise in resistance near the transition pressure, particularly at low temperatures. These findings extended the modification of structure and physical properties of Ni3FeN to high-pressure region, and laid foundation for future material design and applications in antiperovskites.
2026, 45(9): 100967
doi: 10.1016/j.cjsc.2026.100967
Abstract:
The electrochemical CO2 reduction reaction (CO2RR) offers a promising strategy to produce high-value-added C2+ products. Cu-based catalysts enable C-C coupling but suffer from low C2+ selectivity. Although electronic/structural engineering and cation effects have been widely studied, the role of anions in tuning interfacial water structure and CO2RR pathways remains insufficiently understood. Herein, a series of low-concentration anions were introduced into 1 M KOH to regulate the interfacial water environment over reconstructed CuO. By combining in-situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and electrochemical impedance spectroscopy, it is revealed that low-concentration anions in 1 M KOH increase the proportion of strong interfacial-water structure in the order of F- > Cl- > Br- > NO3-. Moreover, the moderate strong interfacial-water structure can accelerate *H transfer and promote *CO hydrogenation to *COH, thus favoring asymmetric C-C coupling to produce C2+ products. However, excessively stable interfacial water structure in F--containing electrolyte induces enhanced *H coverage and dominant H2 evolution. A volcano-type relationship is thus observed between C2+ selectivity and the proportion of strongly hydrogen-bonded water. This work emphasizes anion-mediated interfacial water regulation as an effective strategy to enhance C2+ selectivity for CO2RR.
The electrochemical CO2 reduction reaction (CO2RR) offers a promising strategy to produce high-value-added C2+ products. Cu-based catalysts enable C-C coupling but suffer from low C2+ selectivity. Although electronic/structural engineering and cation effects have been widely studied, the role of anions in tuning interfacial water structure and CO2RR pathways remains insufficiently understood. Herein, a series of low-concentration anions were introduced into 1 M KOH to regulate the interfacial water environment over reconstructed CuO. By combining in-situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and electrochemical impedance spectroscopy, it is revealed that low-concentration anions in 1 M KOH increase the proportion of strong interfacial-water structure in the order of F- > Cl- > Br- > NO3-. Moreover, the moderate strong interfacial-water structure can accelerate *H transfer and promote *CO hydrogenation to *COH, thus favoring asymmetric C-C coupling to produce C2+ products. However, excessively stable interfacial water structure in F--containing electrolyte induces enhanced *H coverage and dominant H2 evolution. A volcano-type relationship is thus observed between C2+ selectivity and the proportion of strongly hydrogen-bonded water. This work emphasizes anion-mediated interfacial water regulation as an effective strategy to enhance C2+ selectivity for CO2RR.
2026, 45(9): 100968
doi: 10.1016/j.cjsc.2026.100968
Abstract:
The demonstration of this superlattice architecture provides a compelling new strategy for the design of advanced photocatalytic materials. Rather than relying on local atomic coordination tuning, this approach utilizes precise epitaxial strain to generate macroscopic electrostatic fields, thereby governing internal charge dynamics. This methodology provides a generalizable strategy: exploiting the QCSE can be extended to other polar material systems—such as transition metal dichalcogenides or polar perovskites—to promote long-lived excitons for various energy conversion applications. Moving forward, addressing the gradual degradation over extended operational periods (e.g., >500 hours) will be crucial for practical applications. Specifically, the chemical leaching of transition metal co-catalysts in harsh saline environments, as observed in the seawater tests, can lead to a continuous loss of active surface redox sites and a subsequent decline in overall catalytic efficiency. To mitigate this issue and enhance long-term durability, future research could focus on employing conformal protective layers, such as those deposited via atomic layer deposition (ALD), or engineering stronger metal-support interactions to anchor the co-catalyst clusters more firmly to the nitride nanowire surfaces. As research increasingly focuses on improving the long-term stability of active sites in such demanding environments, the structural principles demonstrated in this excitonic architecture offer a robust foundation for developing scalable and practically viable artificial photosynthesis systems.
The demonstration of this superlattice architecture provides a compelling new strategy for the design of advanced photocatalytic materials. Rather than relying on local atomic coordination tuning, this approach utilizes precise epitaxial strain to generate macroscopic electrostatic fields, thereby governing internal charge dynamics. This methodology provides a generalizable strategy: exploiting the QCSE can be extended to other polar material systems—such as transition metal dichalcogenides or polar perovskites—to promote long-lived excitons for various energy conversion applications. Moving forward, addressing the gradual degradation over extended operational periods (e.g., >500 hours) will be crucial for practical applications. Specifically, the chemical leaching of transition metal co-catalysts in harsh saline environments, as observed in the seawater tests, can lead to a continuous loss of active surface redox sites and a subsequent decline in overall catalytic efficiency. To mitigate this issue and enhance long-term durability, future research could focus on employing conformal protective layers, such as those deposited via atomic layer deposition (ALD), or engineering stronger metal-support interactions to anchor the co-catalyst clusters more firmly to the nitride nanowire surfaces. As research increasingly focuses on improving the long-term stability of active sites in such demanding environments, the structural principles demonstrated in this excitonic architecture offer a robust foundation for developing scalable and practically viable artificial photosynthesis systems.
2026, 45(9): 100969
doi: 10.1016/j.cjsc.2026.100969
Abstract:
Photocatalytic conversion of CO2 into chemical fuels represents a promising route toward achieving carbon neutrality. However, its practical large-scale deployment is severely hampered, primarily due to high charge-transfer resistance and sluggish kinetics. Herein, a high-crystalline g-C3N4/BiOIO3 (CCN/BIO) S-scheme is constructed through a one-step KI molten salt method, which offers a greener and simpler alternative to conventional systems while enhancing the crystallinity of CCN and enabling the in-situ deposition of BIO. Benefiting from the high lattice matching between the two components, robust N-O-Bi interfacial chemical bonds are formed, serving as efficient channels for charge migration. As a result, the optimized CCN/BIO composite exhibits a markedly enhanced activity of photocatalytic reduction of CO2, with the total yield of CO and CH4 reaching 4.9 and 3.2 times those of pristine BIO and CCN, respectively. Combined density functional theory (DFT) calculations, in-situ irradiated X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) analyses systematically verify the S-scheme charge transfer pathway, which is synergistically driven by the internal electric field and interfacial chemical bonds. This work provides new insights into the rational design of visible-light-responsive S-scheme heterojunction photocatalysts.
Photocatalytic conversion of CO2 into chemical fuels represents a promising route toward achieving carbon neutrality. However, its practical large-scale deployment is severely hampered, primarily due to high charge-transfer resistance and sluggish kinetics. Herein, a high-crystalline g-C3N4/BiOIO3 (CCN/BIO) S-scheme is constructed through a one-step KI molten salt method, which offers a greener and simpler alternative to conventional systems while enhancing the crystallinity of CCN and enabling the in-situ deposition of BIO. Benefiting from the high lattice matching between the two components, robust N-O-Bi interfacial chemical bonds are formed, serving as efficient channels for charge migration. As a result, the optimized CCN/BIO composite exhibits a markedly enhanced activity of photocatalytic reduction of CO2, with the total yield of CO and CH4 reaching 4.9 and 3.2 times those of pristine BIO and CCN, respectively. Combined density functional theory (DFT) calculations, in-situ irradiated X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) analyses systematically verify the S-scheme charge transfer pathway, which is synergistically driven by the internal electric field and interfacial chemical bonds. This work provides new insights into the rational design of visible-light-responsive S-scheme heterojunction photocatalysts.
2026, 45(9): 100970
doi: 10.1016/j.cjsc.2026.100970
Abstract:
Birefringent crystals are critical for advanced photonic technologies, yet achieving substantial optical anisotropy through rational structural design remains a challenge. Herein, we propose a multiscale structural engineering strategy that couples anisotropic functional building units (FBUs) with cation-sulfur mediated dimensional modulation to enhance optical anisotropy. Three new birefringent crystals, K4(2-ABS)4·H2O (I), Rb4(2-ABS)4·H2O (II), and Cs(2-ABS) (III) were identified by mediating the spatial matching between distinct cations and sulfurs to trigger structural evolution. Notably, the structural evolution from a quasi-2D layered arrangement (I and II) to a quasi-1D chain (III) leads to a significant enhancement in birefringence from 0.167 and 0.155 to 0.344 at 532 nm, nearly two orders of magnitude larger than that of K2SO4 and exceeding widely used commercial birefringent crystals. Structural analysis and first-principles calculations reveal a distinct dimensional transition from quasi-2D frameworks (I and II) to a quasi-1D structure (III), where dimensional reduction synergistically cooperates with the intrinsic polarizability anisotropy of [2-ABS]- to markedly enhance birefringence. This work demonstrates the effectiveness and general applicability of multiscale structural modulation as a design principle for birefringent crystal architectures.
Birefringent crystals are critical for advanced photonic technologies, yet achieving substantial optical anisotropy through rational structural design remains a challenge. Herein, we propose a multiscale structural engineering strategy that couples anisotropic functional building units (FBUs) with cation-sulfur mediated dimensional modulation to enhance optical anisotropy. Three new birefringent crystals, K4(2-ABS)4·H2O (I), Rb4(2-ABS)4·H2O (II), and Cs(2-ABS) (III) were identified by mediating the spatial matching between distinct cations and sulfurs to trigger structural evolution. Notably, the structural evolution from a quasi-2D layered arrangement (I and II) to a quasi-1D chain (III) leads to a significant enhancement in birefringence from 0.167 and 0.155 to 0.344 at 532 nm, nearly two orders of magnitude larger than that of K2SO4 and exceeding widely used commercial birefringent crystals. Structural analysis and first-principles calculations reveal a distinct dimensional transition from quasi-2D frameworks (I and II) to a quasi-1D structure (III), where dimensional reduction synergistically cooperates with the intrinsic polarizability anisotropy of [2-ABS]- to markedly enhance birefringence. This work demonstrates the effectiveness and general applicability of multiscale structural modulation as a design principle for birefringent crystal architectures.
2026, 45(9): 100971
doi: 10.1016/j.cjsc.2026.100971
Abstract:
Photocatalytic technology, which enables the direct conversion of solar energy into chemical energy, presents a compelling and sustainable approach to mitigating the pressing issues of the global energy crisis and environmental degradation. S-Scheme heterojunctions have garnered significant attention in photocatalysis due to their exceptional charge separation efficiency and enhanced redox properties. Bismuth-based semiconductors, characterized by their unique layered structures, tunable electronic band configurations, and responsiveness to visible light, offer substantial advantages in the fabrication of S-Scheme heterojunctions. This review systematically summarizes recent advances in Bi-based S-Scheme heterojunctions for photocatalytic applications, focusing on the improvement of charge separation and utilization efficiency. We first elucidate the fundamental charge transfer mechanism of S-Scheme heterojunctions, followed by a comprehensive overview of construction methods including in situ hydrothermal/solvothermal synthesis, electrospinning, calcination, and electrostatically driven assembly. Advanced characterization techniques such as Kelvin Probe Force Microscopy (KPFM), in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS), and femtosecond transient absorption spectroscopy (fs-TAS) for verifying the S-Scheme charge transfer mechanism are discussed in detail. Various modulation strategies to improve photocatalytic performance are thoroughly examined, including electronic structure regulation (element doping and defect engineering), interface structure regulation (electron bridges and crystal facet engineering), and morphology/dimension engineering to optimize the surface reaction. Moreover, the applications of Bi-based S-Scheme heterojunctions in photocatalytic water splitting for hydrogen production, CO2 reduction, pollutant degradation and H2O2 generation are comprehensively summarized. Finally, the current challenges and future perspectives for the development of high-performance Bi-based S-Scheme heterojunction photocatalysts are presented. This review aims to provide profound theoretical insights and strategic frameworks for the rational design of high-efficiency Bi-based S-Scheme photocatalysts.
Photocatalytic technology, which enables the direct conversion of solar energy into chemical energy, presents a compelling and sustainable approach to mitigating the pressing issues of the global energy crisis and environmental degradation. S-Scheme heterojunctions have garnered significant attention in photocatalysis due to their exceptional charge separation efficiency and enhanced redox properties. Bismuth-based semiconductors, characterized by their unique layered structures, tunable electronic band configurations, and responsiveness to visible light, offer substantial advantages in the fabrication of S-Scheme heterojunctions. This review systematically summarizes recent advances in Bi-based S-Scheme heterojunctions for photocatalytic applications, focusing on the improvement of charge separation and utilization efficiency. We first elucidate the fundamental charge transfer mechanism of S-Scheme heterojunctions, followed by a comprehensive overview of construction methods including in situ hydrothermal/solvothermal synthesis, electrospinning, calcination, and electrostatically driven assembly. Advanced characterization techniques such as Kelvin Probe Force Microscopy (KPFM), in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS), and femtosecond transient absorption spectroscopy (fs-TAS) for verifying the S-Scheme charge transfer mechanism are discussed in detail. Various modulation strategies to improve photocatalytic performance are thoroughly examined, including electronic structure regulation (element doping and defect engineering), interface structure regulation (electron bridges and crystal facet engineering), and morphology/dimension engineering to optimize the surface reaction. Moreover, the applications of Bi-based S-Scheme heterojunctions in photocatalytic water splitting for hydrogen production, CO2 reduction, pollutant degradation and H2O2 generation are comprehensively summarized. Finally, the current challenges and future perspectives for the development of high-performance Bi-based S-Scheme heterojunction photocatalysts are presented. This review aims to provide profound theoretical insights and strategic frameworks for the rational design of high-efficiency Bi-based S-Scheme photocatalysts.
2026, 45(9): 100972
doi: 10.1016/j.cjsc.2026.100972
Abstract:
Metal–ligand coordination complexes serve as versatile platforms for the targeted detection of metal ions. However, the relationship between molecular structure, binding interactions, and sensing performance remains dispersed across different sensing systems. This review provides a structure–function perspective on metal–ligand coordination sensors, highlighting how ligand architecture, donor atom types, coordination geometry, and secondary supramolecular interactions collectively influence metal-ion recognition and signal transduction. Particular attention is given to the interaction between primary coordination bonds and auxiliary forces such as hydrogen bonding, π–π stacking, and electrostatic interactions, which together govern binding affinity, selectivity, and sensing behavior. The review discusses key sensing architectures—including preorganized ligands, multidentate chelating probes, supramolecular cages, coordination polymers, and metal–organic frameworks—and demonstrates how structural design principles yield distinct optical and electrochemical responses, such as photoinduced electron transfer, chelation-enhanced fluorescence, and charge-transfer modulation. By connecting molecular design with sensing mechanisms and analytical results, this review establishes a unified framework for understanding metal–ligand coordination-based sensing systems. Finally, emerging strategies to enhance selectivity, stability, and suitability for real-world applications are discussed, offering guidance for designing the next generation of metal-ion sensors for environmental monitoring, biological analysis, and industrial use.
Metal–ligand coordination complexes serve as versatile platforms for the targeted detection of metal ions. However, the relationship between molecular structure, binding interactions, and sensing performance remains dispersed across different sensing systems. This review provides a structure–function perspective on metal–ligand coordination sensors, highlighting how ligand architecture, donor atom types, coordination geometry, and secondary supramolecular interactions collectively influence metal-ion recognition and signal transduction. Particular attention is given to the interaction between primary coordination bonds and auxiliary forces such as hydrogen bonding, π–π stacking, and electrostatic interactions, which together govern binding affinity, selectivity, and sensing behavior. The review discusses key sensing architectures—including preorganized ligands, multidentate chelating probes, supramolecular cages, coordination polymers, and metal–organic frameworks—and demonstrates how structural design principles yield distinct optical and electrochemical responses, such as photoinduced electron transfer, chelation-enhanced fluorescence, and charge-transfer modulation. By connecting molecular design with sensing mechanisms and analytical results, this review establishes a unified framework for understanding metal–ligand coordination-based sensing systems. Finally, emerging strategies to enhance selectivity, stability, and suitability for real-world applications are discussed, offering guidance for designing the next generation of metal-ion sensors for environmental monitoring, biological analysis, and industrial use.
2026, 45(9): 100973
doi: 10.1016/j.cjsc.2026.100973
Abstract:
Photocatalytic overall seawater splitting represents a sustainable route to hydrogen production but is fundamentally limited by chloride-induced catalyst corrosion and competing chlorine evolution reactions. Polymeric photocatalysts are attractive for this process; however, intrinsic chlorine tolerance remains elusive. Here we report that poly (triazine imide) single crystals with exposed {1010} facets enable efficient and stable photocatalytic overall seawater splitting. A surface-bound Cl- layer forms an electrostatic shield that suppresses chloride corrosion, while preferential Na+ adsorption generates a strong interfacial electric field that enhances charge separation and extends carrier lifetimes. Consequently, continuous H₂ and O₂ evolution with a stoichiometric 2:1 ratio and without detectable chlorine by-products is achieved under irradiation in natural seawater. These results reveal an ion–framework cooperative mechanism and establish a feasible design principle for chlorine-tolerant polymeric photocatalysts.
Photocatalytic overall seawater splitting represents a sustainable route to hydrogen production but is fundamentally limited by chloride-induced catalyst corrosion and competing chlorine evolution reactions. Polymeric photocatalysts are attractive for this process; however, intrinsic chlorine tolerance remains elusive. Here we report that poly (triazine imide) single crystals with exposed {1010} facets enable efficient and stable photocatalytic overall seawater splitting. A surface-bound Cl- layer forms an electrostatic shield that suppresses chloride corrosion, while preferential Na+ adsorption generates a strong interfacial electric field that enhances charge separation and extends carrier lifetimes. Consequently, continuous H₂ and O₂ evolution with a stoichiometric 2:1 ratio and without detectable chlorine by-products is achieved under irradiation in natural seawater. These results reveal an ion–framework cooperative mechanism and establish a feasible design principle for chlorine-tolerant polymeric photocatalysts.
2026, 45(9): 100974
doi: 10.1016/j.cjsc.2026.100974
Abstract:
In summary, this study reports a novel single-site cooperativity mechanism that enables high-capacity CO capture, representing a paradigm shift by moving beyond conventional dependence on long-range structural phase transitions. Unlike traditional cooperative systems, which incur substantial energy penalties during regeneration, this localized strategy achieves positive cooperativity through tandem spin transition and reversible migratory insertion at isolated Co(II)-methyl sites. This approach effectively resolves the long-standing trade-off between selectivity and regeneration energy. Effective implementation of this strategy requires integrating spin-active sites within a porous framework. However, several practical challenges remain to be addressed before practical application. For instance, the reactive cobalt-methyl bonds exhibit high sensitivity to atmospheric oxygen and moisture, and the approach also demands precise metal-ligand pairing. Despite these limitations, the mechanism of single-site cooperativity holds promise for extension to the capture or activation of other π-acidic gases, such as NO or SO2, through deliberate engineering of the coordination environment.
In summary, this study reports a novel single-site cooperativity mechanism that enables high-capacity CO capture, representing a paradigm shift by moving beyond conventional dependence on long-range structural phase transitions. Unlike traditional cooperative systems, which incur substantial energy penalties during regeneration, this localized strategy achieves positive cooperativity through tandem spin transition and reversible migratory insertion at isolated Co(II)-methyl sites. This approach effectively resolves the long-standing trade-off between selectivity and regeneration energy. Effective implementation of this strategy requires integrating spin-active sites within a porous framework. However, several practical challenges remain to be addressed before practical application. For instance, the reactive cobalt-methyl bonds exhibit high sensitivity to atmospheric oxygen and moisture, and the approach also demands precise metal-ligand pairing. Despite these limitations, the mechanism of single-site cooperativity holds promise for extension to the capture or activation of other π-acidic gases, such as NO or SO2, through deliberate engineering of the coordination environment.
2026, 45(9): 100975
doi: 10.1016/j.cjsc.2026.100975
Abstract:
In summary, this work establishes a new paradigm for the precision engineering of 2D mesoporous materials. The interface-confined anisotropic assembly strategy not only overcomes long-standing challenges in structural control but also provides a versatile platform for designing advanced functional materials. By decoupling and independently tuning critical structural parameters, this approach opens new avenues for optimizing performance in a wide range of applications, from catalysis and energy storage to smart diagnostics and next-generation therapeutic platforms.
In summary, this work establishes a new paradigm for the precision engineering of 2D mesoporous materials. The interface-confined anisotropic assembly strategy not only overcomes long-standing challenges in structural control but also provides a versatile platform for designing advanced functional materials. By decoupling and independently tuning critical structural parameters, this approach opens new avenues for optimizing performance in a wide range of applications, from catalysis and energy storage to smart diagnostics and next-generation therapeutic platforms.
2026, 45(9): 100976
doi: 10.1016/j.cjsc.2026.100976
Abstract:
Fluorescence lifetime (FL)-based thermometry has been widely applied in diverse technological fields owing to its self-referencing capability, high sensitivity, and reliability. However, conventional FL thermometers generally rely on thermally activated nonradiative relaxation processes, limiting their use for cryogenic sensing below liquid nitrogen temperature (77 K). Herein, we report a new FL thermometric method based on Te4+-doped 0D Cs2ScCl5·H2O crystals, which operates independently of nonradiative relaxation and enables accurate and reliable cryogenic temperature detection down to liquid helium temperature (4 K), achieving a maximum relative sensitivity of 8.5% K–1 at 10 K. Specifically, we demonstrate that the photoluminescence (PL) in Cs2ScCl5·H2O: Te4+ originates from the 3P0,1 → 1S0 transitions of isolated Te4+ centers. This is evidenced by the strong temperature dependence of the dual-band emissions at low temperatures (induced by a dynamic Jahn-Teller effect) and the PL lifetime dictated by the interplay between spin-forbidden and spin−orbital allowed transitions. These findings not only provide fundamental insights into the excited-state dynamics of Te4+ in metal halides, but also establish a general approach for ultralow-temperature FL sensing utilizing main-group s-electron ions.
Fluorescence lifetime (FL)-based thermometry has been widely applied in diverse technological fields owing to its self-referencing capability, high sensitivity, and reliability. However, conventional FL thermometers generally rely on thermally activated nonradiative relaxation processes, limiting their use for cryogenic sensing below liquid nitrogen temperature (77 K). Herein, we report a new FL thermometric method based on Te4+-doped 0D Cs2ScCl5·H2O crystals, which operates independently of nonradiative relaxation and enables accurate and reliable cryogenic temperature detection down to liquid helium temperature (4 K), achieving a maximum relative sensitivity of 8.5% K–1 at 10 K. Specifically, we demonstrate that the photoluminescence (PL) in Cs2ScCl5·H2O: Te4+ originates from the 3P0,1 → 1S0 transitions of isolated Te4+ centers. This is evidenced by the strong temperature dependence of the dual-band emissions at low temperatures (induced by a dynamic Jahn-Teller effect) and the PL lifetime dictated by the interplay between spin-forbidden and spin−orbital allowed transitions. These findings not only provide fundamental insights into the excited-state dynamics of Te4+ in metal halides, but also establish a general approach for ultralow-temperature FL sensing utilizing main-group s-electron ions.
