基于金属硼化物构筑宽光谱响应高效光催化材料的控制制备和机理研究

Photocatalytic water-splitting can provide sustainable green energy for the future society. Highly efficient photocatalysis requires wide-spectrum absorption, high charge-separation property, and active surfaces of photocatalysts, which are also the three aspects to be overcome. Previous efforts have developed methods to improve the properties of photocatalysts, but always narrowly focused on one of the three without synergistic improvements of other two. Based on the knowledge about widening responsive spectrum by doping, promoting charge-separation by constructing heterostructures, and improving surface activity by depositing co-catalysts, the key idea in this project is to make use of metal borides that combine the roles of sources of dopants, precursors of semiconducting metal compounds, and potential Pt-like co-catalysts. It is proposed to construct highly efficient metal-boride/semiconductor heterostructure photocatalysts with broad light absorption spectra, strongly-contacting interfaces and non-noble-metal co-catalysts, and to study the inner mechanism. This project aims to establish the methodology and science of synergistically improving light absorption, charge-separation and surface activity of photocatalysts, and to promote the development of photocatalysis.

利用光催化反应将水分解为氢气和氧气，即光解水制氢，能够为未来社会提供可持续、绿色无污染的能源。高效的光催化反应要求光催化材料同时具有高光吸收范围、高光生电荷分离特性和高表面催化活性三种特性，这也是其面临的三方面限制。近年来的研究获得了许多改善光催化材料特性的方法，但通常只孤立地关注某一方面，不能统筹改善其他两个方面，这限制了其所得效果。基于已有研究中有关掺杂异质原子改善光吸收、构建异质结构促进光生电荷分离以及引入助催化剂改善表面催化活性的认识，本项目拟以既能作掺杂原子源，又可作生长前驱体，还可能具有类Pt催化能力的金属硼化物作为研究基础，通过原位氧化、水解及后续处理，构筑高太阳能转化效率的宽光谱响应、强界面接触、无贵金属利用的金属硼化物/半导体异质结构光催化体系，并研究其内在规律。本项目旨在建立统筹解决光吸收、光生电荷分离和表面催化活性三方面问题的方法和科学，促进光催化研究的发展。

金属硼化物既能够作为掺杂原子源，又可作生长前驱体，还可能具有类贵金属的催化能力。本项目提出基于以金属硼化物作为研究基础，通过原位氧化、水解及后续处里，构筑高太阳能转化效率的宽光谱响应、强界面接触、无贵金属利用的金属硼化物/半导体异质结构光催化体系，并研究其内在规律。本项目执行期间，选定典型的金属硼化物TiB2作为模型材料，通过表面氧化、水解过程的精细调控，成功制备出B在TiO2中均相掺杂、具有高效光催化产氧能力的TiB2@TiO2核壳结构，内、外分别富集锐钛矿相和金红石相的、具有高光生电荷分离特性的双面神型空壳结构，TiB2作为介导材料的、具有Z型电荷转移路线的TiB2@anatase/rutile核壳结构，以及TiB2作为介导材料、CdS对TiO2高效敏化的宽光谱响应的TiB2@TiO2/CdS核壳结构，证实了基于金属硼化物发展宽光谱响应、强界面接触、贵金属替代的金属硼化物/半导体异质结构相关策略的正确性，并阐述了其中的普适性规律。