Enhancing activity and non-deactivating stability on N-modified TiO₂ catalyst for visible-light photocatalytic oxidation of ammonia at room temperature

Nitrogen modified TiO2 catalysts (N-TiO2(1)) with high photocatalytic activity and non-deactivating stability were prepared by using urea as nitrogen source. Its efficiency of photocatalytic oxidation of NH3 (NH3-PCO) remained above 80 %, peaking at 88 % at room temperature over 72 h, while N2 selectivity also improved noticeably, stabilizing at approximately 87.1 %. Conversely, the NH3 conversion on pure TiO2 plateaued at approximately 67 % within 72 h, peaking at only 72.8 %, with nitrogen selectivity not exceeding 55 %. N element was successfully doped into TiO2 lattice system in the form of O-Ti-N, which reduced the band gap energy from 3.18 eV to 3.07 eV and improved the light utilization rate. The water molecules formed during the reaction contribute to the in-situ reaction to continually generate hydroxyl radicals (& sdot;OH), thereby conferring greater reaction stability. By-products NOx- and NOx are formed during the reaction process, while NOx will be also converted to N2 by initial selective catalytic reduction (i-SCR) mechanism. These findings present a novel perspective for enhancing the stability of NH3-PCO active agents and have substantial applications within the parameters of air pollution control.