Dual anions engineering on nickel cobalt-based catalyst for optimal hydrogen evolution electrocatalysis

The hydrogen evolution reaction (HER) is a pivotal process for renewable energy storage devices. Improving the intrinsically catalytic activity of earth-abundant metals based electrocatalysts for HER is still a huge challenge. Herein, we put forward a dual phosphorus/sulfur (P/S) doped nickel-cobalt bimetallic material that was grown on nickel foam (S-n-NiCoPx-NF, n = 1-4, NF stands for nickel foam) through a facile one-step phosphorization/sulfuration reaction. Those catalysts represent a novel kind of electrocatalysts with vastly optimized catalytic activity for HER. The S-2-NiCoPx/NF with optimal P/S ratio achieves unexpectedly highly efficient catalytic activity for HER in alkaline medium. The overpotential at the current density of 50 mA cm(-2) is only 144 mV, which is almost 190 mV less than that of pristine nickel-cobalt bimetallic phosphide catalyst (NiCoPx-NF). In addition, the S-2-NiCoPx/NF also has fast reaction kinetics with the smallest Tafel slope of 66 mV/dec and exhibits high stability for HER. This work experimentally demonstrates the advantages of a dual anion modification strategy on improving catalytic activity. Our method offers a new approach to design highly efficient and low-cost electrocatalysts for energy storage and conversion devices. (C) 2020 Elsevier Inc. All rights reserved.