Porous 2D Catalyst Covers Improve Photoelectrochemical Water-oxidation Performance

Confined catalysis under the cover of two-dimensional (2D) materials has emerged as a promising approach for achieving highly effective catalysts in various essential reactions. Here, a porous cover structure is designed to boost the interfacial charge and mass transfer kinetics of 2D-covered catalysts. The improvement in catalytic performance is confirmed by the photoelectrochemical oxidation evolution reaction (OER) on a photoanode based on an n-Si substrate modified with a NiOx thin-film model electrocatalyst covered with a porous graphene (pGr) monolayer. Experimental results demonstrate that the pGr cover enhances the OER kinetics by balancing the charge and mass transfer at the photoanode and electrolyte interface compared to the intrinsic graphene cover and cover-free control samples. Theoretical investigations further corroborate that the pore edges of the pGr cover boost the intrinsic catalytic activity of active sites on NiOx by reducing the reaction overpotential. Furthermore, the optimized pores, which can be easily controlled by plasma bombardment, allow oxygen molecules produced in the OER to pass through without peeling off the pGr cover, thus ensuring the structural stability of the catalyst. This study highlights the significant role of the porous cover structure in 2D-covered catalysts and provides new insight into the design of high-performance catalysts.

二维（2D）材料包覆限域催化，已成为在各类关键反应中制备高效催化剂的极具前景的策略。本研究设计了一种多孔包覆结构，以提升二维包覆催化剂的界面电荷与传质动力学性能。通过以多孔石墨烯（pGr）单层包覆的NiOx薄膜模型电催化剂修饰n型硅衬底制备的光阳极，在光电化学析氧反应（OER）中的表现证实了催化性能的提升。实验结果表明，相较于本征石墨烯包覆组与无包覆对照组，pGr包覆层通过平衡光阳极-电解液界面的电荷与传质过程，强化了OER动力学。理论研究进一步证实，pGr包覆层的孔边缘通过降低反应过电位，提升了NiOx表面活性位点的本征催化活性。此外，可通过等离子体轰击便捷调控的优化孔径，可使OER过程中产生的氧分子顺利透过而不会剥离pGr包覆层，从而保障了催化剂的结构稳定性。本研究凸显了多孔包覆结构在二维包覆催化剂中的关键作用，为高性能催化剂的设计提供了全新视角。