Visible-Light-Induced photocatalytic oxidation of gaseous ammonia on Mo, c-codoped TiO2: Synthesis, performance and mechanism

Ammonia gas (NH3) is a notorious malodorous pollutant with detrimental effects on environment and human health. Removing NH3 through photocatalytic oxidation remains a challenging task due to unclear reaction mechanisms. In this study, DFT simulation results revealed that C-doped TiO2 could extend the photo-response range to the visible region, but the introduction of deep impurity levels was found to accelerate photogenerated carrier recombination. Fortunately, the rational doping of Mo was found to mitigate this negative effect. Accordingly, Mo, C co-doped TiO2 was synthesized via a facile low-temperature calcination process, resulting in unique band structure that enhanced the photocatalytic oxidation of NH3. Notably, in-situ DRIFTS and DFT results demonstrated that the gradual reaction of NH3 adsorbed on Mo atoms with oxygen species through the N2H4 mechanism, promoting the formation of N2. These findings offer insights into the design of efficient photocatalysts for NH3 removal under visible light, and present a promising technology for indoor air pollution control.