GaN基高效太阳能完全分解水制氢体系构建及光热-催化耦合机理研究

Efficient overall water splitting is both the ideal approach and the difficulty of solar-driven photocatalytic hydrogen production. Simplex photocatalytic hydrogen production usually could only be driven by ultraviolet and visible light while leaving infrared light unadopted, and most of the solar energy is lost/wasted in the form of heat, leading to low solar-to-hydrogen conversion efficiency (STH). During the previous research of the applicant, by controlling the structure of GaN-based semiconductor materials and the water splitting reaction process on the surface, a STH of 2.7% with stable performance more than 580 h was achieved, which is among the best reported numbers. Based on all above, this project proposes a strategy of utilizing the entire solar spectrum to drive the photothermal-catalytic coupling water splitting reaction for hydrogen production. Ultraviolet and visible light could be utilized by GaN-based photocatalyst to generate photo-excited electrons and holes for water splitting. At the same time, infrared light could be utilized by photo-thermal conversion materials to generate the photothermal effect, which could both enhance the charge-carriers density and help the reactant to reach the reactive state. By controlling the composition of photothermal-catalytic coupling reaction system and comprehensive characterization of its various properties, we expect to reveal the mechanism of photothermal-catalytic coupling effect, and to develop the interaction augmentation method of multiple energy-carriers such as photon, phonon, electron, etc., in order to lower the overall energy loss of the entire reaction system. Finally, we expect to accomplish further elevated STH with the ideal overall water splitting system, and to promote the industrial application of this unique technique.

高效完全分解水是太阳能光催化分解水制氢技术的理想途径和难点。单一光催化分解水制氢往往仅能利用紫外及部分可见光，而红外光难以被直接用于驱动光催化分解水反应，太阳光谱中大部分能量以热的形式损耗而制氢效率较低。申请人前期研究中，通过GaN基光催化剂的结构和表面反应过程调控，获得了完全分解水2.7%的太阳能-氢能转化效率及>580小时的稳定性，综合表现处于国际前列。基于此，本项目提出太阳能全光谱驱动光热-催化耦合分解水制氢的思路，GaN基光催化剂利用紫外和可见光产生光生载流子驱动分解水反应，光热转换材料利用红外光产生光热效应提升载流子浓度并活化反应物分子。拟通过光热-催化耦合反应体系组成和结构的调控及性能的全方位表征，揭示光热-催化耦合作用机理，发展光子、声子、电子等多种载能子耦合作用的强化方法，降低反应体系全流程能质损失，实现完全分解水太阳能-氢能转化效率的进一步提高，促进该技术的工业化推广。

太阳能光解水制氢为氢能的绿色制备提供了一种有效的方法。GaN基材料是为数不多的可以实现完全分解水制氢的一类光催化剂，在光催化分解水制氢方面有着巨大的潜力。但以往研究主要关注光催化材料的开发，材料体系对太阳光谱的利用仅限于紫外及部分可见光区间，而红外光区的能量及其光热效应未被利用。.本项目基于GaN基光催化完全分解水制氢材料体系构建对其光热-催化耦合制氢性能及机理进行研究。通过材料组分和结构调控，构建了GaN基光热-催化耦合反应体系，优化了制氢性能，制氢效率处于同类材料体系的国际前列；通过光学、电化学等表征手段结合理论模拟，解析了光热-催化耦合体系中异质结构建强化光生载流子分离和调控分解水反应路径以促进完全分解水性能提升的微观机理；设计了新型光热耦合制氢反应器件，通过调控反应体系与外界环境的热交换强化了光热制氢性能，并考察了GaN基光热-催化耦合体系在分解海水中的应用。此外，为光解水制氢中材料与反应液界面处的载流子动力学研究提供光谱电化学分析方法，并在宽光谱响应材料设计、非贵金属助催化剂制备、光热-催化双功能材料开发等方面进行了拓展研究。.在本项目进行的过程中，共发表SCI论文15篇，其中3篇入选ESI高被引论文，申请/授权发明专利2项，（合作）培养毕业博士研究生1名、硕士研究生1名。项目研究的顺利完成为高效光热-催化耦合制氢体系构建提供了实验基础和理论指导。