Electrocatalytic Activity of a Composite Based on η-Niobium Carbide in Hydrogen Evolution Reaction

The electrocatalytic activity of a new composite material based on η-carbide Nb₃(Fe, Al)₃C in the hydrogen evolution reaction from acidic and alkaline solutions is studied. The composite was obtained by spark plasma sintering of mechanically alloyed niobium, aluminum, and graphite powders in steel containers in petroleum ether, followed by etching in an alkaline solution or in a hydrofluoric acid solution. The composite consists of 78 wt % Nb₃(Fe, Al)₃C, 19 wt % Nb₅Al₃C_x, and 3 wt % graphite; it has a layered structure with a layer thickness of the Nb₅Al₃C_x phase of 50–70 nm. In terms of the magnitudes of overpotential in the hydrogen evolution reaction, the resulting composite is superior to undoped Nb₂CT_x and Nb₄C₃T_x.