Promoting Oxygen Evolution Electrocatalysis by Coordination Engineering in Cobalt Phosphate

Abstract

AbstractUnderstanding the structure‐activity correlation is an important prerequisite for the rational design of high‐efficiency electrocatalysts at the atomic level. However, the effect of coordination environment on electrocatalytic oxygen evolution reaction (OER) remains enigmatic. In this work, the regulation of proton transfer involved in water oxidation by coordination engineering based on Co3(PO4)2 and CoHPO4 is reported. The HPO42− anion has intermediate pKa value between Co(II)‐H2O and Co(III)‐H2O to be served as an appealing proton‐coupled electron transfer (PCET) induction group. From theoretical calculations, the pH‐dependent OER properties, deuterium kinetic isotope effects, operando electrochemical impedance spectroscopy (EIS) and Raman studies, the CoHPO4 catalyst beneficially reduces the energy barrier of proton hopping and modulates the formation energy of high‐valent Co species, thereby enhancing OER activity. This work demonstrates a promising strategy that involves tuning the local coordination environment to optimize PCET steps and electrocatalytic activities for electrochemical applications. In addition, the designed system offers a motif to understand the structure‐efficiency relationship from those amino‐acid residue with proton buffer ability in natural photosynthesis.