Recovery of W–Mo Alloy Scrap and the Photochromic Properties of WO3/MoO3 Composite Products

WO3/MoO3 composites were created via hydrothermal synthesis using W–Mo alloy scrap and poly(ethylene glycol) (PEG). Optimal conditions for photochromism were determined. The composite W1Mo9 displayed superior photochromic properties at a 1:9 W/Mo molar ratio, a 2 h synthesis time, and a 90 °C temperature. Under simulated sunlight, the green hue of WO3/MoO3 shifted to blue. These WO3/MoO3 composites exhibit excellent reversibility and recyclability. Irradiation of WO3 and MoO3 yielded electron–hole pairs, converting them into HxWO3 and HxMoO3 and altering their apparent color. This marks the first-ever conversion of W–Mo alloy scrap into a photochromic material, presenting a method for recycling transition-metal alloy scrap.