Enhanced photocatalytic conversion of NOx with satisfactory selectivity of 3D-2D Bi4O5Br2-GO hierarchical structures via a facile

A novel series of 3D-2D Bi4O5Br2-GO hierarchical composites were fabricated via a facile and efficient microwave-assisted protocol and were systematically characterized by various analyses. In composites, both components of 3D hierarchical Bi4O5Br2 and 2D graphite-phased graphene oxide (GO) were verified in hetero-junction structures by Raman, UV-Vis DRS, TEM, and elemental mapping spectra. Under visible light irradiation, the photocatalytic NOx removal by composites was obviously enhanced with satisfactory selectivity, though removal of NO was remained almost unchanged. Particularly, the best catalog Bi4O5Br2-GO1.6 possessed outstanding conversion rate for NOx increased by 18% and selectivity for nitrite and nitrate declined by 32% comparing to pure Bi4O5Br2, which was mainly relevant to enhanced visible-light harvesting, strengthened spatial separation of photoinduced charge carries, proper phase composition, and harmony of 3D-2D morphology. Moreover, these stable composites could be reused for several times without obvious activity loss. Basing upon entrapping experiments and analytical results, a plausible photocatalysis mechanism was eventually proposed.