Local pH engineering to impact electrocatalysis

Local pH refers to the pH gradient developed within the diffusion layer of the electrode, which can deviate significantly from the bulk value due to proton consumption or generation during electrocatalytic reactions. The proton availability is often a thermodynamic or kinetic limiting factor during electrocatalytic reactions involving proton-electron transfer as determining step. Thus, controlling local pH can effectively impact on both reaction selectivity and activity. In this short review, we present recent advances and strategies emerged to effectively tune the local pH and impact on different electrocatalytic reactions, such as CO 2 reduction reaction (CO 2 RR), electrochemical nitrate reduction (ENR), O 2 reduction reaction (ORR) and ethanol oxidation reaction (EOR). The catalyst engineering approach through microenvironment modification, tuning mass transport conditions by catalyst size and porosity, as well as by pulsed potential electrolysis are the strategies described here.