2D-2D heterostructured composites Bi4O5Br2-SnS2 with boosted photocatalytic NOx abatement

A desirable photocatalytic system ought to feature efficient NOx removal and retardance of toxic NO2 generation. In this investigation, a series of novel two-denominational (2D)-2D composites Bi4O5Br2-SnS2 (X BS) were successfully fabricated through a simple mechanical ball-milling route and characterized systematically. The coexistence of both expected components was confirmed. 2D morphologies of both components were stacked in face-to-face manner and thus formed heterojunction structures, verified by SEM and TEM patterns. The visible-light absorption was enhanced in composites caused by the shrinkage of band gaps. With microstructural and optical merits, these binary composites showed reinforced photocatalytic abatement of NOx and attenuated generation of toxic NO2 under visible light, compared with bare Bi4O5Br2. Successive recycling catalytic experiments revealed the satisfactory reusability and structural stability of achieved composites. Ultimately, a reasonable type-II model was deduced to describe the migration and transfer of interface carriers based on experimental and analytical results. Such work designed and provided various bismuth-based composites constructed by the simple mechanical ball-milling for controlling and treating nitrogen oxides at ppb level in the atmospheric environment.