Positively Charged P-Assisted Ru-Zn Dual Active Sites Promote Oxygen Radical Coupling Mechanism for Acidic Water Oxidation

Abstract

The oxygen evolution reaction (OER) mechanism plays a pivotal role for tuning the activity and stability in an acidic medium. However, obtaining a customized reaction pathway through fine manipulation of the catalyst structure still faces considerable challenges. Herein, we incorporate the Zn single atom and positively charged P into a RuO2 lattice to construct a Zn1P-RuO2-delta catalyst, which enables a heterogeneous dual-site dioxygen radical coupling mechanism (OCM) to release O2, breaking the limitations of activity and stability of traditional adsorbed evolution mechanism. In 0.5 M H2SO4, Zn1P-RuO2-delta shows superior catalytic activity with a mere overpotential of 176 mV at 10 mA cm-2 and significantly extended durability compared to Zn1RuO2-delta and commercial RuO2. Experimental and theoretical studies revealed that the incorporation of the single atom Zn creates an asymmetric Ru-Zn dual site with appropriate geometry, facilitating the formation and direct coupling of dioxygen radicals, while P doping optimizes the adsorption strength of Zn active sites to *O and further reduces the reaction energy barrier of the OCM pathway. This novel mechanism manipulation strategy paves up an optimal catalytic reaction pathway, which would fundamentally improve the efficiency of proton exchange membrane water electrolysis.