Enhanced NO2 sensing performance of S-doped biomorphic SnO2 with increased active sites and charge transfer at room temperature

Abstract

S-Doped biomorphic SnO₂ was synthesized using biomass carbon as a template, where the biomorphic SnO₂ adopts the morphology of the biomass. After the in situ growth of hexagonal or semi-hexagonal SnS₂ on biomorphic SnO₂, the structure of the bio-template was retained. This method is simple, eco-friendly, and cost-effective. The S-termination of SnS₂ can effectively react with NO₂ and thereby improve the gas sensing performance. As expected, the gas sensing performance significantly increased. The S-doped biomorphic SnO₂ shows an excellent response to 100 ppm NO₂ (∼57.38), a fast response time (∼1.60 s), and a low detection limit of as low as 10 ppb at room temperature (RT). The gas sensing performance exhibited strong dependence on the number of S–Sn–O chemical bonds. S–Sn–O chemical bonds can be regarded as bridges for electron transport. Chemical bonds reduced the interface state density and increased the carrier density, resulting in more chemisorbed oxygen and led to more NO₂ reacting with the S-BCS-600 sensor at RT.