Regulating interfacial microenvironment via anion adsorption to boost oxygen evolution reaction

The often-overlooked anions in raw materials have been less explored in terms of their promotion of the oxygen evolution reaction (OER) from the perspective of interfacial microenvironment regulation. In this study, we obtained the catalyst (CoOOH-NO₃^-) by a one-step electrochemical reconstruction method, in which anion adsorption onto the active catalyst can optimize the interfacial microenvironment to promote OER under alkaline conditions. This is because the issue of excessive OH^- adsorption within the inner compact layer of CoOOH can be ameliorated by the adsorption of anions, making it easier for active sites to branch OH^-, thereby regulating the interfacial microenvironment. It was validated through a series of experiments that after tuning the interfacial microenvironment, reduction in the contact angle on the electrode surface facilitates the release of O₂, promotes Co transformation to a higher oxidation state (Co(IV)) and lowers the onset potential for the reaction. Furthermore, the one-step synthesis method, along with the strategy of microenvironment regulation, applies to various metal salts (chlorides, acetates). Our research introduces a non-chemical synthesis method for the direct use of metal salts, providing a rational approach and insight for understanding how anion adsorption regulates interfacial microenvironment to enhance catalytic activity.