可见光响应硒化镉半导体超薄膜的理论设计、制备及光解水性能研究

Photocatalytic water splitting to produce hydrogen is among many solutions of the environmental and energy problem, but the low incident photon-to-current conversion efficiency (IPCE) prevents its practical applications. Ultrathin films are thought to be ideal photoelectrodes for IPCE improvement due to their huge specific surface area and short conducting paths in favor of carrier separation and transport. Herein, we propose to design and prepare the high-performance visible-light responding CdSe semiconductor ultrathin films for photocatalytic water splitting based upon both first-principles calculations and atomic layer deposition (ALD) techniques. We will theoretically study the impact of morphology, doping and heterojunction on the band gaps and photo absorption efficiencies of CdSe semiconductor ultrathin films in order to obtain the ideal structures. Following the theoretical simulations, we will then utilize the ALD techniques to synthesize the targeted CdSe semiconductor ultrathin films for photoelectrodes in a controllable manner by taking advantage of its self-limiting and self-saturation features, and systematically investigate the influence of ALD technology parameters (gas precursors, purge rate, etc.) on the composition, structure and water splitting performance of ultrathin films to reveal their relationship. We are aiming to obtain CdSe semiconductor ultrathin films for photoelectrodes with the merits of high IPCE and visible-light responding, and provide reliable theoretical basis and technical support for the applications of CdSe semiconductor ultrathin films.

光解水制氢是解决环境和能源问题的有效途径之一，但较低的光电转换效率制约着其实际应用。超薄膜因为比表面积大以及有利于载流子的分离和迁移被认为是有助于提高光电转换效率的光阳极理想材料。本项目采用第一性原理计算和原子层沉积技术设计并制备一种高光电性能的可见光响应硒化镉半导体超薄膜光阳极材料。理论研究形貌、掺杂和异质结构对硒化镉半导体超薄膜能带结构和吸光效率的影响规律，得到硒化镉超薄膜的理想结构，并进一步利用原子层沉积自限制性和自饱和性的技术特点可控制备具有理想结构的硒化镉超薄膜，系统研究原子层沉积工艺（气相前驱体、吹扫速度等）对超薄膜结构、组成和光解水制氢性能的影响规律，揭示光阳极超薄膜材料结构、组成与性能之间的内在联系，得到集高光电转换效率和可见光响应于一体的硒化镉半导体超薄膜光阳极，为硒化镉半导体超薄膜的推广应用提供可靠的理论基础与技术支持。

本项目应用第一性原理计算设计了一系列II-VI族二维材料。理论研究了掺杂、合金化、以及异质结构对二维材料能带结构的调控和光电性能的影响。在Nanoscale、J. Mater. Chem. C等高水平期刊发表了9篇SCI论文，并受邀在“Advanced Theory and Simulations”期刊发表相关综述文章“Recent Progress on 2D Group II-VI Binary Chalcogenides ZnX and CdX (X = S, Se, Te): From a Theoretical Perspective. Advanced Theory and Simulations (2019), 2, 1900061.”。此外，我们利用ALD技术制备了ZnO基纳米复合材料，研究发现ALD方法在构筑纳米结构上展现出巨大的优势，此项技术未来在锂电池等方向将会有重大应用前景。综上，本项目研究结果为II-VI族二维材料的推广应用提供了可靠的理论基础与技术支持。