Stabilizing the dissolution kinetics by interstitial Zn cations in CoMoO4 for oxygen evolution reaction at high potential

Abstract

CoMoO4 (CMO), one kind of transition metal oxides, is a promising precursor material for oxygen evolution reaction (OER). However, Mo cations are potentially dissolved into alkaline electrolyte, usually causing an inevitable collapse of CoMoO4 crystal and an unpredictable activity of the reconstructed materials. In this work, interstitial Zn cations in CoMoO4 distort the MoO4 tetrahedrons, and modulate the dissolution kinetics of Mo cations within an approximate level. Therefore, CMO-0.28-Zn with a concentration of 0.28 for Zn/Co exhibits OER performance with an overpotential of 358 mV at 100 mA cm−2 and Tafel slope of 95.5 mV dec−1. Especially, suitable amount of Zn cations enable avoiding the unexpected dissolution of Co cations at high potential. Thus, the durability of the CMO-0.28-Zn catalyst demonstrates the lower current attenuation of 4.5% relative to 9.1% in CMO-0-Zn catalyst without interstitial Zn after 21 h. This investigation indicates that interstitial cations within transition metal oxides can benefit the design of the robust electrocatalysts.