α-Fe2O3光电极温度依赖的载流子传输与表面反应动力学研究

光电催化分解水制氢是一项具有应用前景的绿氢制备技术。光电催化水分解池在实际应用中会受到太阳光辐照导致的温升以及环境温度变化的影响。如经典的光电极材料赤铁矿氧化铁（α-Fe2O3），其光电催化水氧化的起始电位随温度升高而朝不利的方向移动，导致工作曲线偏移，电极的太阳能转换效率降低。揭示影响光电催化的太阳能转换效率随温度变化的瓶颈因素是减轻热场效应带来的负面影响乃至利用热场效应增益光电催化的前提。前期工作表明，α-Fe2O3的带隙随温度上升而减小，有利于光吸收效率的提升，因此，载流子传输或表面反应动力学是光电催化受温度影响的瓶颈过程。本项目拟利用时间分辨的原位谱学来定量分析α-Fe2O3光电极中随温度变化的载流子传输和表面反应动力学过程，并分析其中的瓶颈步骤，探索热场耦合增益光电催化性能的策略。为提高光电催化系统的太阳能转换效率和鲁棒性提供实验支撑，推动光电催化分解水制氢的实用化进程。

Photoelectrochemical (PEC) water splitting is one of the promising techniques for green hydrogen production. In a practical view, the large regional, seasonal and diurnal variation of temperature, and possible heating effect during sunlight irradiation would influence the performance of a solar water splitting cell. For example, hematite (α-Fe2O3), a widely studied photoanode material, exhibits an unfavorable anodic shift of onset potential for PEC water oxidation with increased temperature, leading to deteriorated applied bias photon-to-current conversion efficiency. Identifying the bottleneck process in temperature-dependent PEC behavior is prerequisite to alleviate loss or take advantages from increased temperature. It has been reported that band gap of α-Fe2O3 reduces at increased temperature, indicating more photons could be absorbed. Thus, one or both of the subsequent PEC steps, charge carrier transport or reaction kinetics, would become rate-controlling step in temperature-dependent PEC behavior. In this study, time-resolved in-situ spectroscopic techniques are employed to quantitatively describe the temperature-dependent carrier dynamics and reaction kinetics in α-Fe2O3 photoelectrodes. After the bottleneck step had been found out, strategies would be developed and carried out to mitigate loss during PEC water splitting upon increased temperature, or take advantages of thermally activated chemical reaction. This study will shed light on energy conversion efficiency and robustness of PEC systems under temperature variation, pushing technological readiness level of solar water splitting.