Halide perovskites show great potential in photocatalysis due to their excellent photovoltaic properties. However, severe photogenerated carrier recombination limits its photocatalytic performance. Herein, Cs3Bi2Br9 (CBB) was synthesized via in situ ion exchange on BiOBr, constituting a CBB/BiOBr Z-scheme heterojunction for effective photocatalytic CO2 reduction. Time-resolved photoluminescence (TRPL) spectra and electron spin resonance (ESR) demonstrate that the structure fabricates a Z-scheme heterojunction which can enhance photocatalytic performance by promoting carrier separation and transport. The optimized CBB/BiOBr sample achieves a CO yield of 0.224 μmol h−1, which is 5 and 4 times higher than that of pure BiOBr and CBB, respectively. Furthermore, in situ XPS measurement and DFT calculations are conducted to deeply research the reaction procedure and mechanism of photocatalytic CO2 reduction by CBB/BiOBr composite. In situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) indicates that the detected COOH* intermediate is vital for the highly selective CO generation. This work not only offers a novel idea for the synthetic pathway of bismuth-based perovskite, but also broadens a new system for the effective reduction of CO2 by perovskite.

中文翻译：

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离子交换原位合成无铅钙钛矿 Cs3Bi2Br9/BiOBr Z 型异质结，用于高效光催化 CO2 还原


卤化物钙钛矿由于其优异的光伏性能，在光催化方面显示出巨大的潜力。然而，严重的光生载流子复合限制了其光催化性能。在此，通过在 BiOBr 上进行原位离子交换合成了 Cs3Bi2Br9 （CBB），构成了 CBB/BiOBr Z 型异质结，用于有效的光催化 CO2 还原。时间分辨光致发光 （TRPL） 光谱和电子自旋共振 （ESR） 表明，该结构制造了一个 Z 型异质结，可以通过促进载流子分离和传输来增强光催化性能。优化的 CBB/BiOBr 样品的 CO 产率为 0.224 μmol h-1，分别是纯 BiOBr 和 CBB 的 5 倍和 4 倍。此外，还进行了原位 XPS 测量和 DFT 计算，以深入研究 CBB/BiOBr 复合材料光催化还原 CO2 的反应过程和机理。原位漫反射红外傅里叶变换光谱 （DRIFTS） 表明，检测到的 COOH* 中间体对于高选择性 CO 的产生至关重要。这项工作不仅为铋基钙钛矿的合成途径提供了新思路，而且拓宽了钙钛矿有效还原 CO2 的新系统。