α-SnWO4纳米薄膜晶面取向可控制备及其光电化学分解水性能研究

The α-SnWO4 (~ 1.9 eV) is a promising photoelectric catalytic material, but the photoelectrochemical water splitting performance is limited by its weak bulk charge transfer ability. The crystal facet and orientation have an important effect on the charge transfer of photocatalysts. However, there is still a lack of in-depth studies on the crystal facet regulation of the α-SnWO4 thin film and its effect on the photocatalytic water splitting. In this project, in-situ transformation method is adopted to obtain α-SnWO4 nanostructured films with special preferred growth orientation by changing the proportion of exposed facets of WO3 nanostructure films and the reaction conditions, exploring the facet regulation mechanism of α-SnWO4. Based on the photoelectrochemical test and theoretical calculation results, the influence of crystal facets and orientations on the photoelectrochemical properties were analyzed. Meanwhile, by adjusting the composition of different crystal facets of α-SnWO4 (etching to reduce the Sn atom ratio and in situ transformation to construct α-/β-SnWO4 homophase heterojunction on the surface), systematic researches will be taken to analyze the relationship between the characterizations of crystal facets structure of α-SnWO4 and the photoelectrochemical feature. This study will clarify the mechanisms and general rules of promoting the transport of photoexcited charge carriers by synergistically controlling crystal orientations and crystal facet structures. The results obtained could guide the development of high-efficiency and stable photoelectrodes for photoelectrochemical water splitting.

α-SnWO4（~1.9 eV）是具有发展潜力的光（电）催化材料，但体相电荷传输能力较弱限制了其光电化学分解水性能。光催化剂的晶面取向对材料的电荷传输行为起到至关重要的作用，然而关于α-SnWO4薄膜的晶面调控及其对光解水催化性能影响的机制尚缺乏深入研究。本项目拟采用原位转化的方法，通过改变WO3的暴露晶面比例、原位转化的反应条件，实现α-SnWO4纳米结构薄膜晶体取向生长的可控制备，并阐明相关调控机制；基于光电化学测试和理论计算结果，探究晶体取向与光电催化分解水性能的关系；与此同时，通过对α-SnWO4不同晶面组成结构进行调节（刻蚀减少Sn原子所占比例、表面原位转化构筑α-/β-SnWO4同相异质结），系统研究α-SnWO4晶面结构、光电催化特性之间的关系，揭示基于晶体取向和晶面结构的双重调控来促进光生载流子传输的规律与机制，为发展高效稳定的光电光催化材料的研发提供理论依据和实现途径。

α-SnWO4（~1.9 eV）和CuWO4（~2.3 eV）是具有发展潜力的光（电）催化材料，但体相电荷传输能力较弱限制了其光电化学分解水性能。鉴于晶面取向对材料的电荷传输行为具有重要作用，本项目通过原位转化法和一步水热法分别实现了α-SnWO4和CuWO4晶面取向的有效调控，并结合理论计算和光电化学测试方法研究了材料的晶面效应。主要进展为：①通过优化原位转化的反应条件（WO3母版、pH、时间、阴离子种类），实现α-SnWO4纳米结构薄膜晶体取向生长的可控制备，F离子有助于暴露｛001｝面，且具有较高的水氧化活性；②通过离子吸脱附作用，对α-SnWO4薄膜表面Sn/W原子比进行调控，表面富Sn后提供了空穴在表面的存在空间，促进光电催化水氧化反应的发生；③开发乏氧条件下沉积产氧电催化剂，避免材料合成中将Sn2+氧化，并在此基础上构建电催化剂/保护性碳层/α-SnWO4薄膜，将其光电分解水性能从文献报道的0.1 mA/cm2提升至~1.7 mA/cm2；④基于阴离子在不同晶面上的吸附性差异，水热法直接合成不同轴向生长的CuWO4薄膜，并揭示轴向对薄膜电极体相电荷传输的影响行为。本项目提供了化学法晶向诱导生长纳米结构阵列薄膜方法，揭示基于晶体取向和晶面结构的双重调控来促进光生载流子传输的规律与机制，为发展高效稳定的光电光催化材料的研发提供理论依据和实现途径。