Fig. 6: Schematics of the reducing gas sensing mechanism in the hierarchical highly ordered nanobowl SnO2@ZnO NWs.

a The three-dimensional schematic of the hierarchical highly ordered nanobowl SnO2@ZnO NWs exposed in H2S gas; b, c the schematic energy band diagrams for the hierarchical SnO2@ZnO NWs: b in separate state and c in air. The band structure data in figure (b) were determined from the literature48