Abstract

Overcoming the problems of high dissociation energy and slow activation of N₂, photocatalytic nitrate reduction to ammonia (PcNRA) is considered a sustainable and more advantageous approach compared to N₂ fixation. Additionally, removing water pollution and converting waste nitrates into valuable ammonia is attracting attention as an eco-friendly alternative to ammonia production technology. However, it suffers from low ammonia selectivity and yield. In this study, hollow SrTiO₃ nanospheres decorated with copper nanoparticles were used to increase photocatalytic activity by spatially separating the reduction sites in the outer shell of hollow SrTiO₃, prioritizing photocatalytic nitrate reduction to ammonia reaction, and increasing ammonia selectivity using copper nanoparticles. The optimal photocatalyst containing 3 % Cu nanoparticle decoration/SrTiO₃ showed a high ammonia selectivity of 84.1 % and ammonia yield of 2.14 μmol h⁻¹ and a high apparent quantum yield of 2.8 % at 330 nm, while pristine hollow SrTiO₃ nanospheres showed no activity for ammonia production by nitrate reduction.