Vacancy-modified bimetallic FeMoSx/CoNiPx heterostructure array for efficient seawater splitting and Zn-air battery

Abstract

The development of highly efficient OER catalysts with superior durability for seawater electrolysis and Zn-air battery is important but challenging. Herein, the vacancy-modified heterostructured bimetallic FeMoSx/CoNiPx OER electrocatalyst is exploited. Benefiting from the electron redistribution and reaction kinetics modulation resulting from vacancy introduction and heterojunction formation, it yields ultralow OER overpotentials of 196, 276, 303 mV in 1 M KOH and 197, 318, 348 mV in 1 M KOH + seawater at 10, 500, 1000 mA cm−2, respectively, surviving 600 h at 800 mA cm−2 without obvious decay. Further, FeMoSx/CoNiPx-based Zn-air battery not only affords the high peak power density of 214.5 mW cm−2 but also exhibits the small voltage gap of 0.698 V and long lifetime of 500 h at 10 mA cm−2, overmatching overwhelming majority of reported advanced catalysts. It is revealed experimentally that the OER process on rationally designed FeMoSx/CoNiPx follows the adsorbate evolution mechanism and the rate-determining step shifts from *OOH formation in individual building blocks to *OOH deprotonation process in FeMoSx/CoNiPx, providing the directly proof of how the vacancy introduction and heterojunction formation affect the reaction kinetics.