Enhanced Electrocatalytic Oxygen Reduction on NiWO_x Solid Solution with Induced Oxygen Defects

The continuous solid solution NiWO_x is successfully prepared by using precursor W₁₈O₄₉ with plenty of oxygen defects. The NiWO_x nanoparticles are characterized by X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray absorption spectroscopy. The crystallographic phase of NiWO_x is stable and characterized by the same feature of the parent lattice W₁₈O₄₉ even with various concentrations of dopant Ni which indicates the existence of oxygen defects. The NiWO_x nanoparticles could be processed as the appropriate promoter after loading 10 wt % Pt. The Pt/NiWO_x displays remarkable response for oxygen reduction reaction in alkaline medium compared with the commercial Pt/C. The analysis of the electrochemistry data shows that the existence of abundant oxygen defects in the solid solution NiWO_x is the key factor for the improved ORR catalyst performance. Ni is effective in the catalysts because of its compatibility with W in the solid solution and its active participation in oxygen reduction reaction.