Structural properties of tungsten-doped cobalt molybdate and its application in electrochemical oxygen evolution reaction

New tungsten-doped CoMoO4 (W-CoMoO4) was successfully synthesized by a simple co-precipitation method and investigated for a possible application in oxygen evolution reaction (OER). The effect of W6+ doping on structure, morphology, and chemical compositions was investigated by X-ray diffraction spectroscopy, scanning electron microscopy, Fourier transform spectroscopy, Brunauer-Emmet-Teller surface area measurement, and X-ray photoelectron spectroscopy. Linear sweep voltammetry indicates that doping CoMoO4 with an optimum W6+ amount of 21 wt% provides higher current density at lower overpotential than other catalysts. Compared to undoped CoMoO4, the 21 wt% W-CoMoO4 also shows a remarkable activity and excellent long-term stability in alkaline media. This superior activity is ascribed to the synergistic effect of increased oxygen vacancy, enhanced surface area, and possibly improved electrical conductivity upon W6+ doping. The significances of this work are that the potential OER application of Co-W-Mo tertiary oxide, which has never been studied before, and the effect of non-3d high-valency metal (W) doping on OER activity enhancement are now being recognized.