In-Situ Generation of Ni-Coooh Through Deep Reconstruction for Durable Alkaline Water Electrolysis

Abstract

The surface-reconstruction-induced layer on transition metal-based catalysts during electrocatalytic oxygen evolution reaction (OER) is considered to be responsible for their catalytic activity. However, how the active layer forms and works in the OER process has not been understood clearly. Here, we demonstrate a facile approach to reveal the mechanism for the formation of active layer and its role in OER by fabricating the NiCo-based hybrids as precatalysts. We find that the anodization can improve its OER activity, leading to a low OER overpotential of 276 mV at 10 mA cm −2 and favorable durability (≥100 h). In - situ Raman spectroscopy and ex - situ characterizations reveal that the Ni-CoOOH nanosheets array with promising surface wettability is generated via deep reconstruction during the OER process and the high-valence Co is the active site for efficient oxygen evolution. Theoretical analysis further illustrates that the Co site can be activated by the Ni incorporation, thus optimizing the adsorption capability toward the intermediates. This work provides new perspectives to recognize the active site and insightful understanding to rationally design the electrocatalysts for practical applications.

Keywords: Oxygen evolution reaction, Deep reconstruction, Ni-CoOOH nanosheet, In-situ Raman spectroscopy