Lignocellulose is Earth’s most abundant form of biomass and its valorization to H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ is a key objective for the generation of renewable fuels. Solar-driven photocatalytic reforming of lignocellulose to H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ 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 H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ 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 H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ through waste biomass oxidation.