无铅三金属钙钛矿纳米晶的可控合成与高效光(电)催化CO2还原

In the past 3 years, all-inorganic lead-free perovskite nanocrystals (NCs) have attracted extensive attention due to their low toxicity, high stability and outstanding optoelectronic property. Thus, this scientific research program intends to investigate the controllable synthesis of lead-free all-inorganic trimetal perovskite nanocrystals and their applications in efficient photocatalytic or photoelectrocatalytic reduction of CO2. The “up-down” ultrasound exfoliation method or hot-injection approach will be adopted to prepare the ingenious and representative lead-free trimetal perovskite NCs such as 2D-layered A4MIIM2IIIX12 (Cs4CuSb2Cl12) or 3D A2MIMIIIX6 (Cs2AgBiBr6), and the solar driven CO2 reduction ability for each of them will be evaluated via solid-liquid or solid-gas mode. Through sufficient optimization of the experiment conditions, a series of novel, lead-free, trimetal perovskite NCs with broad absorption, high stability, low toxicity and excellent optoelectronic property will be obtained, and their photophysical and photochemical properties (e.g. light harvesting ability, electron transport and recombination mechanism, trap state density) will be thoroughly investigated. Particularly, femtosecond transient absorption spectroscopy and electrochemical characterizations will be used to reveal the influence of size, bandgap and composition of the synthesized lead-free trimetal perovskite NCs on the selectivity and conversion efficiency of photocatalytic reduction of CO2. Such study will offer new ideas for the design of lead-free perovskite NCs and their applications in photo/electro-catalytic field.

纯无机无铅钙钛矿纳米晶因其低毒、高稳定性和优异光电性能等优点近3年来受到了广泛关注。本项目拟围绕纯无机三金属无铅钙钛矿纳米晶的可控合成与高效光（电）催化CO2还原的核心科学问题开展研究。拟重点发展“自上而下”的超声剥离法创新合成以Cs4CuSb2Cl12为代表的二维A4MIIM2IIIX12无铅三金属钙钛矿纳米晶及热注入法合成以Cs2AgBiBr6为代表的A2MIMIIIX6无铅三金属钙钛矿纳米晶，并开展固-液和固-气模式的光（电）催化CO2还原研究。旨在优化合成一系列吸收光谱宽、稳定性好、无毒且性能优异的新颖无铅三金属钙钛矿纳米晶，并深入研究其光捕获能力、电子传输与复合、缺陷密度等光物理和光化学性质。利用飞秒瞬态吸收光谱和电化学等手段，揭示不同金属组成、尺寸和能带的无铅三金属钙钛矿纳米晶对光催化还原CO2产物选择性和转换效率的影响，为无铅钙钛矿纳米晶的合成与光（电）催化应用提供新思路。

本项目围绕无铅钙钛矿纳米晶材料的设计、合成及其在光催化领域的应用开展了创新研究。通过溶液相化学法制备了三金属无铅Cs4CuSb2Cl12、Cs3Bi2X9和Cs3Sb2X9（X=Cl、Br、I）、CsCuCl3和CsCuCl2Br等钙钛矿纳米晶，调控了材料的光学带隙；构建了一系列Cs2SnI6纳米晶/SnS2纳米片II型异质结、α-Fe2O3纳米棒/胺基-RGO/CsPbBr3纳米晶Z型异质结、2D/2D CsPbBr3/Bi2WO6 Z-型异质结，大大提升了电荷分离，从而实现了高性能光催化CO2还原；构建了一系列钙钛矿-助催化剂体系，包括MAPbI3/CoP异质结、CsPbBr3亚微米晶表面负载Pt纳米颗粒、CsPbBr3–Au复合材料，且拓展合成了Cs4MnBi2Cl12等一系列钙钛矿单晶等，在光电催化、光电探测和发光方面等均获得了优异的性能。探究了材料组成、结构与光催化性能之间的关系，并利用飞秒瞬态吸收光谱、开尔文探针显微镜、原位光照X光电子能谱、光电化学仪器等先进表征手段详细研究了光生载流子产生、分离和传输的机制，为新型无铅钙钛矿材料的设计、合成及其高性能光催化应用提供了坚实的研究基础和可行的思路。