半导体晶体基人工光合成体系的研究

Based on crystal engineering, this project will develop some novel nano- or micro-sized semiconductor crystals with different facets, aiming at giving in-depth understanding on the observed facet charge separation. The feasibility of overall water splitting by the semiconductor crystal-based artificial photosynthesis system will be extensively explored by selective deposition of oxidation and reduction cocatalysts on the corresponding redox facets of the semiconductor crystals. And with the assistance of various kinds of modern spectroscopic studies and theoretical calculations, the fundamental micro-processes involved in the water splitting reactions will be explored, with special focus on the process of light absorption, generation and separation of electrons and holes upon photoexcitation, charge carrier mobility and transport, and water splitting reactions on the surface reactive sites. This project will give great insight into the fundamental mechanisms of water splitting reaction on the semiconductor crystal-based artificial photosynthesis systems, which may serve as a meaningful guidance for the development of more efficient overall water splitting systems.

本研究项目将通过晶体工程，发展新型的纳米或微米尺度的、可见光吸收的、具有不等同晶面的高结晶度的半导体晶体材料，深入研究晶面电荷分离效应；通过在不等同晶面上选择性担载能带和晶相匹配的氧化和还原双助催化剂的方法，探索构建晶体基人工光合成体系高效光催化分解水的可行性。借助于光谱研究和理论计算，深入研究晶体基人工光合成体系中光的吸收、光生电子和空穴的产生和分离、载流子的迁移和传输、水的还原和氧化反应等微观过程及其相应机制，进而为构建高效光催化分解水的晶体基人工光合成体系提供坚实的实验与理论基础。

本项目围绕光生电荷有效分离和转移这一光催化分解水制氢和二氧化碳转化制太阳能燃料的关键科学问题之一开展研究工作。合成了双钙钛矿等一系列具有不等同晶面的半导体光催化材料，深入研究了晶面电荷分离的机理；通过在等同晶面上光沉积担载氧化和还原双助催化剂，实现了高效光催化氧化水。同时探索了光生电荷有效分离和转移的心方法、新策略：利用铁电材料自带的自发极化场促进光生电荷的有效分离，并进一步结合形貌控制，构建铁电晶面电荷分离材料，大大促进了光催化氧化水的活性；首次实现异相结光阳极的构建并证明光电催化中异相结促进光生电荷有效分离；首次从热力学角度揭示了半导体与分子催化剂之间可能的多电子转移过程，为基于多电子转移机理构建高效光催化体系提供了新的研究思路；首次揭示了-MnO2能够在酸性条件下稳定氧化水超过8000小时的电压工作窗口，为发展非贵重金属基氧化水催化剂提供了可能。所有这些工作，为将来进一步人工光合成太阳能燃料奠定了良好的基础。