Hierarchical star-like molybdenum phosphides nanostructures decorated graphene on 3D foam as self-supported electrocatalyst for hydrogen evolution reaction

Abstract

Fabrication of efficient electrocatalysts for hydrogen evolution reaction (HER) is important to produce hydrogen fuel on a large scale via electrocatalytic water splitting. In this research, a novel electrocatalyst based on star-like molybdenum phosphide structure vertically grown on highly conductive graphene supported by a three-dimensional nickel foam (MoP/GR/NF) was synthesized via a facile hydrothermal method followed by a phosphidization strategy at 300 °C. The exclusive hierarchical nanostructure with abundant porosity was beneficial for enhancing active site numbers and electrical conductivity. In particular, the formation of Mo–P impressively changed electronic structure of the resulting material, thereby accelerating electrocatalytic activity for HER in 1.0 M KOH medium. The MoP/GR/NF required small overpotentials of 95 and 189 mV to deliver current densities of 10 and 50 mA cm−2, respectively. In addition, it also demonstrated a Tafel slope of 54 mV dec−1, which was significantly smaller than that of the GR/NF, Mo–O/GR/NF, and Mo–P/NF. Furthermore, there was negligible decrease of current response and overpotential for a continuous HER during long-term operation, implying its excellent stability. The prospective catalytic activity and good stability of the MoP/GR/NF material could prospectively open a new aspect for developing effective electrocatalyst for hydrogen production in water splitting application.