Oxygen vacancies in actiniae-like Nb₂O₅/Nb₂C MXene heterojunction boosting visible light photocatalytic NO removal

Photocatalytic oxidation is a green and energy-saving technology for removing the low concentration NO in ambient atmosphere. High efficient and stable photocatalysts are essential for achieving excellent NO conversion effect. In this work, oxygen vacancy-rich Nb₂O₅/Nb₂C heterojunction photocatalysts were prepared from Nb₂C MXene by hydrothermal process and heat treatment in H₂/Ar. The (001) facet-dominant Nb₂O₅ nanorods in-situ grown on Nb₂C MXene formed an actiniae-like structure, which promotes the active site exposure and enlarges the reaction interface. Under visible light, the optimized photocatalyst exhibits excellent NO removal rates in the relative humidity range of 25–75%. Mechanism research shows that the oxygen vacancies greatly improve the photocatalytic NO oxidation capacity. Oxygen vacancies on (001) facet of Nb₂O₅ nanorods can boost the visible light absorption, effectively adsorb and activate the reactant gas. The separation of photogenerated carriers was synergistically enhanced by the oxygen vacancies and Nb₂O₅/Nb₂C heterojunction.