Enhanced photocatalytic ammonia oxidation activity and nitrogen selectivity over Ag/AgCl/N-TiO photocatalyst.

The removal of ammonia (NH) emitted from agricultural and industrial activities is of great significance to protect human health and ecological environment. Photocatalytic NH oxidation to N under mild conditions is a promising strategy. However, developing visible light photocatalysts for NH oxidation is still in its infancy. Here, we fabricate N-TiO and Ag/AgCl/N-TiO photocatalysts by sol-gel and photodeposition methods, respectively. The introduction of N not only endows TiO with visible light response (absorption edge at 460 nm) but also results in the formation of heterophase junction (anatase and rutile). Thus, N-TiO shows 2.0 and 1.8 times higher than those over anatase TiO and commercial TiO for NH oxidation under full spectrum irradiation. Meanwhile, surface modification of Ag can simultaneously enhance visible light absorption (generating localized surface plasmon resonance effect) and charge separation efficiency. Therefore, the photocatalytic activity of Ag/AgCl/N-TiO is further improved. Furthermore, the presence of N and Ag also enhances the selectivity of N product owing to the change of reaction pathway. This work simultaneously regulates photocatalytic conversion efficiency and product selectivity, providing some guidance for developing highly efficient photocatalysts for NH elimination.