Synthesis of Nanostructured Tungsten-Based Catalyst from Scheelite Ore for Electrocatalytic Oxygen Evolution Reaction

This study presents an integrated low-temperature processing route that converts tungstic acid and ammonium paratungstate derived from scheelite ore (CaWO4) into nanoscale tungsten trioxide (WO3), metallic tungsten (W), and tungsten carbide (WC) via solid-state reaction, hydrogen reduction, and gas–solid reaction, respectively. This approach enables particle size control, reduced energy consumption, and enhanced functional properties, enabling evaluation of the materials’ performance in the oxygen evolution reaction (OER). X-ray diffraction (XRD) confirmed the formation of the desired phases with nanocrystalline structures and average crystallite sizes of 13.3 nm (WO3), 31.55 nm (W), and 10.35 nm (WC). The materials exhibited homogeneous morphologies, demonstrating the effectiveness of the synthesis routes. Electrochemical measurements revealed promising OER activity; the WO3 electrode showed the lowest overpotential of 321 mV at 10 mA cm−2, while W and WC showed 327 mV and 340 mV, respectively, in 1.0 M KOH. Overall, the results demonstrate a strategy for scheelite valorization.