Photocatalytic hydrogen production from formic acid over waste derived Au-based catalysts

• A pioneering approach for the preparation of Au/TiO 2 photocatalysts from Au(I)-glycine leachate solutions derived from spent materials. • Formic acid is employed for the photocatalytic hydrogen production. • The pH of the solution affects both the photocatalyst preparation and the photocatalytic activity. • The temperature of the reactive system strongly influences the photocatalyic hydrogen generation. Photocatalytic hydrogen generation has garnered increasing attention in recent years. However, the practical application of many developed catalysts remains limited due to their dependence on expensive noble metals (e.g., gold) and modest hydrogen production rates. Traditional gold-based photocatalysts typically utilize Au(III) precursors, whose extraction involves hazardous chemicals such as strong acids, hydrogen peroxide, and chlorine-containing byproducts, raising significant environmental and safety concerns. In this study, we present an innovative synthesis route for Au/TiO 2 photocatalysts using leaching solutions containing Au(I) and glycine as an alternative, less hazardous gold source. This approach eliminates the need for conventional Au(III), offering a more environmentally friendly and sustainable method without compromising catalytic efficiency. The resulting photocatalysts were extensively characterized and evaluated for hydrogen evolution using formic acid as a sacrificial agent under UV-A/visible light irradiation. Key parameters including gold loading, system temperature, and pH were systematically optimized, with the best performance achieved at 5 wt% Au loading, 70 °C, and pH 5.0, yielding 6000 µmol H 2 /g after 100 min. The materials also demonstrated excellent stability and reusability across multiple cycles. These results highlight a promising, scalable strategy for clean hydrogen production that integrates green chemistry principles with waste valorization, offering an efficient and practical solution for sustainable energy applications.