An efficient strategy for selective oxidation of ammonia nitrogen into N2 over BiOCl photocatalyst

Selective oxidation of ammonia nitrogen (NH4+-N) into N-2 is critical to remove the superfluous nitrogen in the hydrosphere and control the fixed nitrogen inventory for the global nitrogen cycle. Herein, on the basis of chlorine radical chemistry, we report the photocatalytic denitrogenation over BiOCl with high N-2 selectivity (>97 %). Efficient Cl- conversion into reactive chlorine species (RCS) is achieved, serving as the predominant reactive species for NH4+-N oxidation. According to the zero-order kinetics of Cl- for RCS generation, as well as the Cl- extraction/insertion over BiOCl, a Cl--mediated Mars-van Krevelen mechanism is revealed, by which the catalytic performance shifts from the undesired deactivation (because of photocorrosion) towards the remarkably enhanced reactivity. This system exhibits great potential for the denitrogenation of saline wastewater, also provides an interesting strategy to activate inert chemical bond via the chlorine cycle.

Automated summary

Selective oxidation of ammonia nitrogen into N-2 over BiOCl with high N-2 selectivity (>97%) is reported based on chlorine radical chemistry. The efficient Cl- conversion into reactive chlorine species and Cl--mediated Mars-van Krevelen mechanism contribute to the enhanced reactivity of the catalytic performance.