Metal Oxide/Graphene/Metal Sandwich Structure for Efficient Photoelectrochemical Water Oxidation

Single-layer graphene (SLG) has drawn considerable interest in photoelectrochemical (PEC) cells due to its atomically flat pinhole-free structure and remarkable in-plane carrier mobility. It is challenging, however, to obtain efficient SLG-modified photoelectrodes for PEC water splitting mainly due to the inefficient charge transfer interface. Here we construct a transition metal oxide/SLG/transition metal sandwich structure modified n-Si-based model photoanode to regulate the interfacial charge transfer behavior for enhanced PEC water oxidation performance. In this sandwich configuration, SLG tailors the morphology, structure, and work function properties of surface metal electrocatalysts to obtain both higher thermodynamic photovoltage and faster kinetical charge transfer at the semiconductor/electrolyte interface. In addition, SLG promotes the surface catalytic reaction as an effective charge trap and storage layer. Our work provides a new structural design to engineer the SLG interfacial properties for high-performance energy conversion devices.

单层石墨烯（Single-layer graphene，SLG）因具备原子级平整无针孔的结构与优异的面内载流子迁移率，在光电化学（photoelectrochemical，PEC）电池领域受到广泛关注。然而，由于电荷转移界面效率低下，制备用于PEC水分解的高效SLG修饰光电极仍颇具挑战。本文构建了过渡金属氧化物/SLG/过渡金属三明治结构修饰的n型硅基模型光阳极，以调控界面电荷转移行为，进而提升PEC水氧化性能。在该三明治构型中，SLG可调控表面金属电催化剂的形貌、结构与功函数特性，从而在半导体/电解液界面同时获得更高的热力学光电压与更快的动力学电荷转移速率。此外，SLG作为有效的电荷俘获与存储层，可促进表面催化反应。本研究为调控SLG界面特性以制备高性能能量转换器件提供了全新的结构设计思路。