Nuoya Li,Xujian Chen,Jin Wang,Xinmeng Liang,Lintao Ma,Xiaolang Jing,De-Li Chen,Zhengquan Li
Utilizing sunlight to convert CO2 into chemical fuels could simultaneously address the greenhouse effect and fossil fuel crisis. ZnSe nanocrystals are promising candidates for photocatalysis because of their low toxicity and excellent photoelectric properties. However, pristine ZnSe generally has low catalytic activities due to serious charge recombination and the lack of efficient catalytic sites for CO2 reduction. Herein, a ZnSe nanorods–CsSnCl3 perovskite (ZnSe–CsSnCl3) type II heterojunction composite is designed and prepared for photocatalytic CO2 reduction. The ZnSe–CsSnCl3 type II heterojunction composite exhibits enhanced photocatalytic activity for CO2 reduction with respect to pristine ZnSe nanorods. The experimental characterizations and theoretical calculations reveal that the efficient charge separation and lowered free energy of CO2 reduction facilitate the CO2 conversion on the ZnSe–CsSnCl3 heterojunction composite. This work presents a type II heterojunction composite photocatalyst based on ecofriendly metal chalcogenides and metal halide perovskites. Our study has also promoted the understanding of the CO2 reduction mechanisms on perovskite nanocrystals, which could be valuable for the development of metal halide perovskite photocatalysts.
Ziyan Wu,Qiqi Zhang,Binghan Li,Zhifang Shi,Kaimin Xu,Yi Chen,Zhijun Ning,Qixi Mi
All-inorganic metal halide perovskites are noted for their excellent optoelectronic properties and good chemical stability but also a propensity to transform into nonperovskite phases. A case in point is lead-free CsSnCl3, whose perovskite Phase I is metastable at room temperature and could not be stabilized by partial substitution of Cs+ or Cl–. Judging from the radii of the constituent ions of CsSnCl3, we paid attention to octahedral cations smaller than Sn2+ and selected Mn2+ and In3+ for substitution at the B-site. A quantitative structural indicator, volume per formula unit (V/Z), guided the syntheses of CsSn0.9Mn0.1Cl3 (CTMC) and CsSn0.9In0.067Cl3 (CTIC), which are shown by single-crystal X-ray diffraction and differential scanning calorimetry to be homogeneous, stable perovskite phases at room temperature. CTMC turns into a disordered perovskite structure at 193 K, lower than the corresponding transition temperature of CsSnCl3 by nearly 100 K. Vacancies in CTIC result in a more flexible crystal structure than CTMC and CsSnCl3. CTMC and CTIC appear bright yellow with a steep absorption edge at ∼450 nm, and their photoluminescence peaks are located at 645 and 484 nm, respectively, with intensities significantly enhanced from CsSnCl3. Energy transfer processes are proposed to account for the Stokes shifts in the photoluminescence of CTMC and CTIC. Thin films of CTMC glow red under ultraviolet excitation and hold promise for electroluminescence devices. This study gives insights into the structural and electronic effects of ionic substitution in CsSnCl3 and can be extended to other metastable perovskite phases.
We report a rapid synthesis method for producing CsSnCl3:Mn2+perovskites, derived from SnF2, and investigate the effects of rapid thermal treatment on their photoluminescence properties. Our study shows that the initial CsSnCl3:Mn2+samples exhibit a double luminescence peak structure with PL peaks at approximately 450 nm and 640 nm, respectively. These peaks originate from defect-related luminescent centers and the 4T1→6A1transition of Mn2+. However, as a result of rapid thermal treatment, the blue emission is significantly reduced and the red emission intensity is increased nearly twofold compared to the pristine sample. Furthermore, the Mn2+-doped samples demonstrate excellent thermal stability after the rapid thermal treatment. We suggest that this improvement in photoluminescence results from enhanced excited-state density, energy transfer between defects and the Mn2+state, as well as the reduction of nonradiative recombination centers. Our findings provide valuable insights into the luminescence dynamics of Mn2+-doped CsSnCl3and open up new possibilities for controlling and optimizing the emission of rare-earth-doped CsSnCl3.
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