Enhanced photocatalytic NO removal over AgCu alloy modified UiO-66-NH2 promoting charge transfer

Photocatalytic NO removal technology is considered as one of the most effective green methods for reducing atmospheric NO but there remains the problems of lower efficiency and poor stability of photocatalysts. Rapid recombination of photogenerated electron (e−) and holes (h+) is known as a key issue that causes low activity and poor stability of catalysts. Herein, we report a novel AgCu@UiO-66-NH2 photocatalyst (AgCu@UN) that is made up of AgCu alloy on the surface of Zr-MOF (UiO-66-NH2) by employing in-situ photodeposition method. The experimental results of photocatalytic NO removal indicated that the optimized 0.5Ag0.5Cu@UN sample with 0.5 mg of Ag and Cu exhibited the best NO removal efficiency of 63 % for ppb-level atmospheric NO, more higher than that of pure UiO-66-NH2 (38 %). The characterizations suggested that the excellent photocatalytic performance of 0.5Ag0.5Cu@UN can be ascribed to the efficient charge separation and transfer and the visible-light-harvesting ability due to benefiting electron migration process between AgCu alloys and UN. Moreover, the enriched electrons around AgCu could be transferred to O2 to generate more superoxide radicals (•O2−), which could oxidize NO to the final product, nitrate (NO3−). The present findings can provide some novel insights for the design of efficient MOF based photocatalysts to eliminate low concentrations of NOX.