Enhancement of catalytic activity in infinite-layer nickelates for the oxygen evolution reaction

Engineering efficient electron-transfer processes by tailoring the surface electronic state is a rational approach to developing active electrocatalysts. While advanced experimental techniques and theoretical calculations have progressively unveiled the relationship between electrocatalysis and electronic states, with a focus on perovskite-type metal oxides, many aspects of catalytic descriptors remain unclear. Transitioning from traditional perovskite frameworks, this study demonstrates infinite-layer nickelates, characterized by square-planar lattice and half-filled dx²-y² orbital configuration, as a novel model system for understanding the design of highly active electrocatalysts. Specifically, infinite-layer nickelates exhibit significantly higher activity for the oxygen evolution reaction compared to their perovskite counterparts, with an onset potential difference of 310 mV. This enhanced performance is evidenced by their large electric double-layer capacitance, which indicates an electrochemically active surface. Density functional theory calculations with a Hubbard U term (DFT+U) confirm the higher OER activity of the infinite-layer nickelates and relate it to the lower oxidation state of Ni at the infinite-layer surface compared to the perovskite. Thus, it is expected that our findings, highlighting high catalytic activity in square-planar NiO4 with a unique d-orbital configuration, will provide a new design strategy for exploring highly active electrocatalysts.