Modulating electronic structure of support for boosting H2 generation in alkaline medium

Abstract

The sluggish kinetics of the hydrogen evolution reaction (HER) in alkaline media have been ascribed to the extra energy required to split water molecules and generate protons. Herein, the HER performance in an alkaline medium was enhanced by fabricating a catalyst consisting of metallic Ni on Fe-doped MoOx nanosheets (Ni/Fe-MoOx) to promote water dissociation. The Ni/Fe-MoOx catalysts only requires a low overpotentials of 36 mV and 167 mV to achieve current densities of 10 and 100 mA cm−2 in 1.0 M KOH, respectively. This is better than the performance of Ni/MoOx catalysts. The excellent electrocatalytic HER performance of Ni/Fe-MoOx can be ascribed to the stronger water dissociation ability caused by Fe doping, which was demonstrated by DFT calculations and in-situ FTIR spectra, providing more available protons in the alkaline medium. Moreover, Fe doping boosts the oxygen evolution reaction (OER) performance of the Ni/Fe-MoOx catalysts in the alkaline media via the in-situ formation of Fe doped NiOOH during the OER process. Thus, using the Ni/Fe-MoOx catalysts as both the anode and cathode in a water splitting device results in a low cell voltage of 1.50 V at a current density of 10 mA cm−2, as well as excellent stability within 24 h. This work paves a novel way for synthesis of high-performance bifunctional electrocatlysts.