核壳结构异质结的氧化物纳米线阵列的制备与光电化学制氢研究

To achieve efficient photoelectrochemical water splitting, the semiconductor photoanode should meet the criteria in terms of band gap, carrier mobility, band edge position, and corrosion resistance. Unfortunately,to date, there is no semiconductor material meets all the requirements simultaneously. Nanostructure and duplex structure can improve or modify the performance of materials significantly and this can be a breakthrough for the photoelectrochemical hydrogen production research. This proposal describe the deposition of core-shell structural heterojunction using one dimensional(1D) metal oxide nanowire arrays with good electron mobility as the core and a conformal coating with narrow band gap semiconductor as shell.This core-shell structural heterojunction extend the activity spectrum to visible light region and improve the separation of photo-excited carriers at the same time and prevent reverse reaction and finally achieve efficient photoelectrochemical water splitting. At first, structural optimized 1D metal oxide nanowire arrays will be deposited with simple, low-cost and clean methods including low temperature solution and hydrothermal method.Then conformal layer of narrow band gap semiconductor will be deposited on the nanowire to form a core-shell heterojunction followed with structural optimization and interface engineering. At last by intense investigation of charge carrier transport and separation mechanism in the nanowire and heterojunction, charge carrier transport kinetics model will be proposed. This will provide guide lines for structural optimization and new approach to achieve high effcient photoelectrochemical water splitting.

在光电化学制氢研究中，目前研究的半导体材料都不能完全满足高效光电化学分解水对半导体的禁带宽度、电子迁移率、带边位置、抗腐蚀性等的所有要求，利用特殊形貌和复合结构可以对材料的性能进行增强或改变，有可能成为光电化制氢研究的突破口。本项目将以导电性好的氧化物半导体制备一维纳米线阵列，并构建核壳结构异质结实现响应光谱的扩展和光生载流子的强化分离，阻止逆反应，实现高效光电化学制氢。首先，利用简单、低成本、无污染的低温溶液法和水热法制备导电性好的一维纳米线阵列，实现可控生长和优化形貌结构；在此基础上生长窄禁带半导体包裹层，构建核壳结构异质结，并进行结构优化和界面缺陷控制；最后，利用先进表征手段，探索半导体光电极内部电荷迁移规律、核壳结构异质载流子强化分离，建立的载流子动力学模型，对核壳结构异质结阵列的制备优化提供指导原则，最终为未来实现高效的太阳能制氢提供新途径。

在太阳能光电化学制氢研究中，高效的光能吸收和光生载流子分离是实现高效光电化学分解水的关键。本项目设计和制备了多种氧化物半导体材料的一维纳米线阵列，并构建核壳结构异质结实现响应光谱的扩展和光生载流子的强化分离，实现高效光电化学制氢，在以下几个方面进行了深入研究：1）首先，对TiO2和WO3纳米线阵列进行进一步形貌和结构优化，提高比表面积的同时减少晶界密度；2)其次，在此基础上构建多种异质结结构，并对不同形貌的核壳结构异质结的性质进行分析，研究其载流子分离增强机理；3)最后，通过表面助催化剂的改性，表面元素掺杂修饰进一步提高表面反应，探索半导体表面反应过程，实现载流子的最大化利用。项目对一维纳米线阵列的设计和合成、核壳结构异质半导体光电极内部电荷强化分离规律以及光电化学表面反应改性和动力学过程优化提供指导原则，可以为今后进行高效的太阳能制氢研究提供实验经验和理论指导。