Bias‐Free Solar‐Driven Ammonia Coupled to C3‐Dihydroxyacetone Production through Photoelectrochemistry

Abstract Conversion of solar energy into value‐added chemicals through photoelectrochemistry (PEC) holds great potential for advancing sustainable development but limits by high onset potential which affects energy conversion efficiencies. Herein, we utilized a CuPd cocatalyst‐modified Sb 2 (S,Se) 3 photocathode (CuPd/TSSS) to achieve an ultra‐low onset potential of 0.83 V RHE for photoelectrochemical ammonia synthesis. Meanwhile, we achieved unbiased NH 3 production by synthesizing major value‐added C 3 ‐dihydroxyacetone (DHA) through glycerol oxidation on the BiVO 4 photoanode with the loading Pd cocatalyst, instead of a traditional solar water oxidation reaction. The PEC integrated system stably produced 11.98 μmol cm −2 of NH 3 and 201.9 mmol m −2 of DHA over 5 h with ~80 % faradaic efficiency without applying additional bias. In situ analysis and theoretical calculations confirmed high catalytic activity for ammonia synthesis at the CuPd/TSSS photocathode and enhanced selectivity for DHA at the Pd/BiVO 4 photoanode. This design represents a breakthrough in directly utilizing solar energy, nitrate‐containing wastewater, and biomass waste for ammonia and highly value‐added C 3 production, which addresses increasing energy demands while decreasing environmental impact.