Hang Mei,Zi-Yan Wang,Yue Zhai,Qiang-Qiang Zhu,Le Wang,Pei Liang
Vacancy-ordered double perovskites, the variant of metal-halide perovskites, have excellent potential for use in optoelectronic and thermoelectric devices. A narrow region of forming the stable vacancy-ordered double perovskite Cs2PdBr6 by the chemical potential calculation via the first principles method was reported. Perdew–Burke–Ernzerhof functionals were used to investigate the possible intrinsic defects and the corresponding formation energy of Cs2PdBr6. Under the Pd-rich condition, the VBr defect was spontaneously formed as it has the lowest formation energy among all donor defects. In contrast, the sample became a p-type conducting material with a high hole concentration under the Pd-poor condition. This indicates that the defect-induced decline of photoelectric properties of Cs2PdBr6 can be alleviated by regulating the VBr defect alone. Finally, the Cs2PdBr6 microcrystals were fabricated via hydrothermal synthesis. In addition, XRD, PL, and Raman spectroscopy were also performed on Cs2PdBr6 powder to characterize the microstructure and optical properties of the compound; the results showed that VBr defects can be formed spontaneously, which is consistent with our theoretical calculations.
Baoyi Liu,Haibo Ning,Zhenghao Gong,Junsheng Chen,Bin Yang,Yuanyuan Feng,Huan Liu,Tianxin Bai,Qingkun Kong
Halide perovskites exhibit exceptional optoelectronic properties, including strong light absorption and efficient generation of photogenerated charge carriers. However, these advantages are extremely limited in electrocatalytic systems, and their full potential remains largely unexplored. In particular, the underlying mechanisms governing light-assisted electrocatalysis in perovskite materials remain poorly understood. Herein, a Pt-modified Cs2PdBr6 all-inorganic halide perovskite (Cs2PdBr6@Pt1.5) is designed, which achieves a low overpotential of 11 mV at 10 mA cm–2 with excellent water stability. Femtosecond transient absorption spectroscopy further demonstrates that the incorporation of Pt increases the population of transient species (<1 ps) and acts as an efficient charge separation channel, thereby promoting charge migration to catalytic active sites and enhancing hydrogen evolution reaction properties. Density functional theory (DFT) calculations reveal that electrons transfer from Cs2PdBr6 to Pt, and Pt-modified Cs2PdBr6 optimizes the adsorption energies of key reaction intermediates, thereby lowering the overpotential for water splitting. These findings highlight the potential of halide perovskites as a stable and efficient platform for light-assisted electrocatalytic water splitting and related energy conversion processes.
Wen Ye,Jing-Hui He,Qiang Cao,Wu-Ji Sun,Jia Wang,Ze-Kun Chen,Xue-Feng Cheng,Chuang Yu,Jian-Mei Lu
Owing to their special photoelectric properties, halide perovskites have always attracted research attention. Hollow-structured halide perovskites have many practical applications but are challenging to prepare as most template methods violate their poor chemical and thermal stability. In this study, novel halide perovskite Cs 2 PdBr 6 hollow nanospheres are prepared using a template-free method; specifically, large quantities of highly pure lead-free halide perovskite Cs 2 PdBr 6 hollow nanospheres are produced at 30 °C without a surfactant. These ultrapure nanospheres exhibit superiority in chemresistive detection of CO with a detection limit of 50 ppb, which is the lowest among all the reported CO sensing materials. Moreover, in situ sum-frequency-generation spectra and density functional theory calculations reveal that the high sensitivity is attributable to the large specific surface area and surfactant-free surface of rich Br − vacancies that favor CO binding. Overall, this work provides insight on regulation of the halide perovskite structure and the use of hollow spheres in gas-sensing applications.
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