Brønsted base tuning the local reaction environment to enhance neutral water oxidation

Abstract

The neutral oxygen evolution reaction (OER) in lower OH−-concentration environments suffers from sluggish reaction kinetics, presenting significant challenges for the design of efficient and low-cost electrocatalysts. Effectively manipulating the local reaction environment could provide a promising solution. Here, we report a Brønsted base silicate (SiO₃²⁻)-modified NiFe(OH)x catalyst. As a proton acceptor, Brønsted base SiO₃²⁻ accelerates the cleavage of OH-H bonds at Ni/Fe sites (*H2O → *OH + H+ + e−), thereby facilitating *OH accumulation and enhancing the local *OH-enriched reaction environment. With these advantages, the optimized NiFe(OH)x-SiO32- catalyst exhibits a low OER overpotential of 280 mV at 10 mA cm⁻², a 150 mV reduction compared to the unmodified NiFe(OH)x catalyst. Furthermore, the membrane electrode assembly electrolyzer using NiFe(OH)x-SiO32-||Pt/C achieves an energy conversion efficiency of 69.2% and a current density of 1.0 A cm⁻² at 1.81 V, maintaining stable performance over 240 hours with a negligible degradation. The strategy of Brønsted base SiO₃²⁻ modification offers a promising and cost-effective approach for enhancing the efficiency of neutral water electrolysis.