近红外响应的无重金属AgInSe2/AgInSexS1-x/AgInS2量子点研究及其光电制氢应用

Photoelectrochemical solar-hydrogen conversion (PEC-H2) is an effective way to convert and store solar energy directly, while traditional semiconductor photocatalysts exert relatively simple composition/structure, poor utilization of solar energy and unsatisfied reaction efficiency. The ternary I-III-VI2 quantum dots (QDs) are one of the most promising alternatives thanks to their size/composition-adjustable optical properties, theoretically high solar-hydrogen energy conversion rate (STH) and heavy-metal-free composition. At present, heavy-metal-free QD-PEC cells present poor efficiency and stability, which greatly limit their development. For the first time, we propose to synthesize the visible (Vis)- and near-infrared (NIR)-active AgInSe2/AgInSexS1-x/AgInS2 QDs through continuous ion-exchange. Their structure/interface/surface control mechanism will be deeply investigated by combining theoretical calculation and various characterization methods. The QDs will be engineered accordingly to enhance the light absorption ability, improve carrier separation and reduce carrier recombination, eventually promoting the PEC reaction as a consequence. To improve the light-harvesting ability, for the first time, the co-sensitized structure concept will be introduced into the heavy-metal-free QD-PEC system. Assisted with FDTD simulation and characterizations, the key factors affecting light response of the double-sided photoelectrode can be identified. On the basis of this study, highly efficient heavy-metal-free QD-based double-sided photoanode will be constructed, and the relationship between material structure and performance will be revealed, clarifying the kinetic mechanism of PEC, and providing new research ideas for designing efficient QDs catalysts with broad spectral response.

光电制氢（PEC-H2）是直接存储太阳能的有效手段，而传统光解水催化剂存在不易调控、光利用率低、活性差等不足。三元I-III-VI2量子点（QDs）因其光学特性尺寸/组分可调、理论上太阳能-氢能转化率（STH）高、不含重金属等优点，有潜力替代传统催化剂，但目前其PEC体系的STH较低且稳定性差。本研究拟通过连续离子交换法首次合成近红外光响应AgInSe2/AgInSexS1-x/AgInS2核/过渡层/厚壳QDs。为提高光能利用，率先将双敏化结构理念引入无重金属QD-PEC-H2体系。通过结合密度泛函理论计算、FDTD仿真模拟和表征手段，研究QDs结构、界面及光学性能调控机制并探明影响双面光电极响应的核心因素。通过研究，可实现基于多元QD的PEC双面光阳极的理性调控，揭示材料结构与性能的关联，阐明PEC反应及动力学机制，构筑高效、稳定的PEC系统，为设计PEC光催化剂提供新思路。

光解水制氢（PEC）是直接存储太阳能的有效手段，而传统光解水催化剂存在合成不易调控、光利用率低、活性差等不足。三元量子点（QDs）因其光学特性尺寸/组分可调、理论上太阳能-氢能转化率高、不含重金属等优点，有潜力替代传统催化剂，但目前其基于三元量子点的PEC体系对太阳光光能利用率低且稳定性差。本项目通过连续离子交换法首次合成近红外光响应AgInSe2/AgInS2核/厚壳量子点。通过结合密度泛函理论计算和表征手段，揭示了量子点界面过渡层是光学性能调控及影响光电极响应的核心因素。因此，通过设计调整母版量子点的结构，我们实现AgInSe2/AgInSeS/AgInS2量子点的结构。通过电泳沉积，我们实现了基于多元核/多元壳QD的光阳极的理性调控，通过光电性能系统分析，揭示了多元核多元壳量子点的结构对电子空穴的转移的影响，提出了量子点中过渡层界面设计对光催化性能的决定性作用。项目为多元量子点的合成提供新的思路, 也为设计类似的PEC光催化剂提供实验依据和理论指导。