半导体纳米异质结构的可控合成及表面等离子体共振增强光电性能研究

Noble metal-semiconductor hybrid nanocatalysts play an important role in the photo-electrocatalytic water splitting for hydrogen production. However, their narrow light absorption leads to low utilization efficiency of light energy, and the lattice mismatch causes the suppressed charge separation. Therefore, developing the economical and highly efficient catalysts is the focus and difficulty in the related research. In this project, the synthesis of transition metal chalcogenide semiconductor nanoheterostructures would be carried out by the epitaxial growth strategy in the liquid phase. The coupling between Cu2-xS (or Cu2-xSe) which exhibits a broad-spectrum light absorption and the electrocatalytic active NSy (N = Ni, Co, Fe) aims to form the heterostructured photo-electrocatalyst with lattice-matched and well-defined heterointerface, efficiently utilizing the solar light for electrocatalytic water splitting. Moreover, the internal relation between the micro-structures of the catalysts and their photo-electrocatalytic performance would be explored, and the micro-mechanism of the energy transfer would be further investigated. The advantages are as follows: 1) The surface plasmon resonance of Cu2-xS can effectively enhance the absorption of solar light from the visible to near-infrared region, improving the sunlight utilization efficiency; 2) The intimate, coherent heterointerface with well-matched lattices is beneficial for fast charge separation; 3) Adjusting the structural parameters of nanocrystals which influence their performance, such as size, morphology, composition and so on, could construct the high catalytic active sites, leading to comprehensive enhancement of the photo-electrocatalytic performance. This project is expected to provide innovative materials, novel structures and new methods for the rational design and precise construction of the novel, high efficient and low-cost photo-electrocatalysts.

贵金属-半导体复合纳米催化剂在光电解水制氢中发挥了巨大作用，但其窄的光谱吸收导致光能利用率低，其界面晶格失配易造成电荷分离受阻，因此，发展经济、高效的新型催化剂是相关研究的重点与难点。本项目拟采用外延生长策略，液相合成过渡金属硫属半导体异质结纳米晶，将宽光谱吸光Cu2-xS(Se)与电催化活性MSy(M=Ni,Co,Fe)耦合，形成晶格匹配、界面明确的异质结光电催化剂，高效利用太阳光辅助电解水反应，并探讨催化剂微结构与光电催化性能的内在联系及能量转移的微观机制。优点如下：1)利用Cu2-xS表面等离子体共振，可有效增强可见-近红外区太阳光的吸收，提高太阳光利用效率；2)异质结界面紧密连续、晶格匹配，电荷分离迅速；3）通过调控影响性能的结构参数，如尺寸、形貌、组成等，构建高活性催化位点，全面提升光电分解水性能。以期为合理设计和精准构筑新型、高效、低成本的光电催化剂提供新材料、新结构、新方法。

纳米异质结构由不同构筑基元组成，复合构筑基元之间可通过化学键、界面相互作用产生电荷迁移、物质传输和能量转移，相对于传统催化剂具有独特的、可调控的光、电、催化活性和选择性等优势。该项目围绕纳米异质结构的合成方法学、微观结构调控和构效关系等几个方面开展了较为系统的研究，并取得了系列重要进展：（1）发展了半导体纳米异质结构的系列合成方法学，实现了纳米异质结构中尺寸、组成、表界面结构、几何维度的控制合成，并进一步发展了双金属纳米晶及金属-配体原子级分散位点等多组分催化剂的调控制备方法，形成若干种新型复合结构催化剂；（2）探究半导体纳米异质结构催化剂的微结构参数对物理化学性质的影响，如空间电荷分离、能带调控、电子结构重构、反应物吸附等，提炼提升催化性能的关键机制；（3）较为系统的研究了具有不同表界面结构和电子态的纳米异质结构的光催化、电催化性能，从原子和分子层面上认识光、电催化反应机理。项目执行期间在国际重要期刊上共计发表SCI论文4篇，包括J. Am. Chem. Soc.（热点论文、高被引论文）、Adv. Func. Mater.、ACS Appl. Mater. Interfaces、Inorg. Chem.；此外，该项目资助下1篇论文投稿并修改，仍有论文整理待发表。通过项目的执行，获得了纳米异质结构的新材料、构建方法和规律性认识，为基于性质要求进行纳米催化剂结构设计、提高综合性能奠定了良好基础。