Constructing ultrahigh-loading unsymmetrically coordinated Zn-N3O single-atom sites with efficient oxygen reduction for H2O2 production

Precise synthesis of single-atom catalysts (SACs) with both high loading and special configuration, not just transition metal-nitrogen co-doped carbon (M−Nx−C), to achieve large-scale and widespread application is greatly attractive but challenging. Herein, unsymmetrically coordinated Zn-N3O SAC with ultrahigh-loading of Zn up to 11.34 wt% is synthesized by means of a pre-adsorption-anchoring and pyrolysis approach. The strong adsorption of Zn ions by polypyrrole (PPy) and its inherent N/O source, coupled with the anchoring effect of ZIF-8 on Zn ions, is conducive to direct bonding between N/O atoms and Zn ions and the formation of high-loading atomic-scale Zn-N3O moieties, which are favorable for H2O2 production with a high selectivity up to nearly 100%. Density functional theory (DFT) computations further disclose that unsymmetrically coordinated Zn-N3O moieties tailor the ΔGOOH* near the peak of the volcano plot for 2e− ORR and therefore maximize the catalytic selectivity to form H2O2.