Solar-driven reforming of lignocellulose to H2 with a CdS/CdOx photocatalyst

Lignocellulose is Earth’s most abundant form of biomass and its valorization to H2 is a key objective for the generation of renewable fuels. Solar-driven photocatalytic reforming of lignocellulose to H2 at ambient temperature offers a sustainable route towards this goal, but this reaction is currently limited to noble-metal-containing systems that operate with low activity under ultraviolet light. Here, we report the light-driven photoreforming of cellulose, hemicellulose and lignin to H2 using semiconducting cadmium sulfide quantum dots in alkaline aqueous solution. We show that basic conditions cause these dots to become coated with oxide/hydroxide in situ, presenting a strategy to improve their photocatalytic performance. The system operates under visible light, is stable beyond six days and is even able to reform unprocessed lignocellulose, such as wood and paper, under solar irradiation at room temperature, presenting an inexpensive route to drive aqueous proton reduction to H2 through waste biomass oxidation. Photoreforming can produce H2 through the simultaneous reduction of water and the oxidation of organic molecules, such as those derived from biomass, but cheaper and more active photocatalysts are required. This study shows that CdS/CdOx produces H2 from unprocessed lignocellulose suspensions at high rates under solar illumination.