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

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.