Regulating the Electrochemical Microenvironment of Ni(OH)2 by Cr Doping for Highly Efficient Methanol Electrooxidation

Abstract

Nickel-based catalysts demonstrate promising potential in integrated hydrogen production via methanol electro-oxidation (MOR). However, the MOR involves multiple hydroxide ions (OH^–) and multielectron synergistic catalytic processes in alkaline electrolytes. The low OH^– capture capability of Ni-based catalysts leads to a reduced energy conversion efficiency. Furthermore, the competitive adsorption of H₂O and CH₃OH molecules on the catalyst surface blocks active sites, resulting in a decreased selectivity for formate. To address these challenges, effectively manipulating the electrochemical microenvironment has emerged as a viable strategy. In this study, we successfully achieved selective electrooxidation of methanol to formate on Ni(OH)₂ by incorporating a hard Lewis acid heteroatom (Cr) to finely tune the electrochemical interface microenvironment. Experimental and theoretical investigations reveal that incorporating ordered Cr atoms into Ni(OH)₂ can establish a hydrophobic interface, suppressing the blockage of active sites and promoting the enrichment of OH^– at the electrified interface. By leveraging the enhanced localized alkalinity and hydrophobic microenvironment at the modified electrified interface, high-value formate can be effectively synthesized with nearly 100% selectivity over a wide potential range. Furthermore, the catalysts display robust electrocatalytic capabilities, delivering remarkable performance with a high current density of 50 mA cm^–2 at a working potential of 1.45 V vs RHE.