Directional Surface Reconstruction of C and S Co-Doped Co2vo4/Cop for the Cooperative Enhancement of Hydrogen Production Via Seawater Electrolysis

Abstract

The endeavor to architect bifunctional electrocatalysts that exhibit both exceptional activity and durability heralds an era of boundless potential for the comprehensive electrolysis of seawater, an aspiration that, nevertheless, poses a substantial challenge. Within this work, we delineate the meticulous engineering of a three-dimensional, interconnected nanoparticle system, designated as S and C co-doped Co2VO4/CoP (hereinafter referred to as S-C-P-Co2VO4), achieved via a meticulously orchestrated sequence of hydrothermal treatments, succeeded by gaseous carbonization and phosphorization endeavours. The resultant S-C-P-Co2VO4 electrode unveiled a distinguished bifunctional electrocatalytic stability in 1M KOH solution, a feat attributable to the astute optimization of anion doping alongside a proliferated assortment of heterogeneous interfaces. This electrode prodigiously necessitated an extraordinarily minimal overpotential of merely 92 and 350 mV to attain current densities of 10 and 50 mA cm-2 for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, in 1M KOH solution. Noteworthily, when integrated into an electrolyzer for the exhaustive splitting of seawater, the S-C-P-Co2VO4 manifested an exceptionally low cell voltage of 2.08 V@50 mA cm-2 and showcased a durability that eclipses that of most hitherto documented nickel-based bifunctional materials. Further elucidation through Density Functional Theory (DFT) analyses underscored that anion doping and the inherent heterostructure adeptly optimize the Gibbs free energy of intermediates comprising hydrogen, chlorine, and oxygen (manifested as OH, O, OOH) within the HER and OER paradigms, thus propelling the electrochemical kinetics of seawater splitting to unprecedented velocities. These revelations unfurl a pioneering design philosophy for the creation of cost-effective yet superior catalysts aimed at the holistic division of water molecules, charting a course towards the realization of efficient and sustainable hydrogen production methodologies.

Keywords: Bifunctional electrocatalysts, Electrolytic seawater, electrocatalysis, Nanoparticle