Photocatalytic CO 2 Conversion Driven by UV Light Above 300 nm Using Ammonia as an Electron Donor

Efficient utilisation of solar UV light ( λ > 300 nm) is essential for practical photocatalytic CO 2 conversion. However, in conventional systems using water as an electron donor, slow water oxidation kinetics present a critical bottleneck that severely limits the CO production rate. Here, we demonstrate an efficient CO 2 conversion system that overcomes this kinetic limitation by employing ammonia as an alternative electron donor over Mg-doped SrTiO 3 loaded with Ag and Fe as dualcocatalysts (Ag–Fe/Mg–SrTiO 3 ). Under UV irradiation ( λ > 300 nm), the optimised photocatalyst achieved a remarkable CO produc on rate exceeding 200 μmol h −1 . Mechanistic investigations revealed that the Fe cocatalyst played a crucial role in promoting ammonia oxidation, facilitating the rapid consumption of photogenerated holes, and significantly enhancing CO 2 conversion activity. Furthermore, nitrite (NO 2 − ) was successfully quantified as the primary oxidation product of ammonia, yielding a calculated e − / h + balance of approximately 1.2, validating the stoichiometric relationship of the reaction. This study offers a promising strategy for simultaneously achieving the upcycling of CO 2 and effective utilisation of ammonia as both an energy source and an electron donor.