Phytic Acid‐Induced Oxygen Vacancies in Self‐Supporting NiCo Metal‐Organic Frameworks for Efficient Oxygen Evolution Reaction

Abstract

ABSTRACT The sluggish kinetics of the oxygen evolution reaction (OER) impede efficient water electrolysis, motivating the development of robust, non‐precious‐metal electrocatalysts. Here, we construct a self‐supported bimetallic metal–organic framework precatalyst (PAx‐NiCo‐BDC) through a two‐step strategy using phytic acid (PA) for mild etching and multidentate coordination. This treatment introduces oxygen‐vacancy‐related coordination defects and regulates the precursor morphology. The optimized PA3‐NiCo‐BDC requires only 212 mV to reach 10 mA cm − 2 , exhibits a Tafel slope of 20.2 mV dec − 1 , and shows excellent durability, outperforming commercial RuO 2 . An anion‐exchange‐membrane water electrolyzer employing PA3‐NiCo‐BDC delivers 1 A cm − 2 at 1.72 V and operates stably for 300 h. In situ Raman spectroscopy reveals that PA‐induced defects enable the lower‐potential formation of Ni 3+ –O‐containing NiOOH‐like surface species. Differential electrochemical mass spectrometry identifies the adsorbate evolution mechanism as the dominant OER pathway. Density functional theory calculations further show that defect‐induced d‐band‐center modulation optimizes the adsorption and desorption of OER intermediates at Ni sites and lowers the OER energy barrier. This green coordination‐engineering strategy provides a versatile route to efficient and durable MOF‐based electrodes for practical water electrolysis.