Construction of SnO₂/SnS₂ n-n heterojunction anchored on rGO for synergistically enhanced low temperature formaldehyde sensing performance

Creating metal oxide heterostructures is a promising way to enhance sensing performance by modulating their electronic properties. Herein, SnO2/SnS2 n-n heterojunction anchored on rGO (3.84 % of SnS2) was constructed using a hydrothermal route and fabricated as sensors for detecting formaldehyde (HCHO). The response value of the SnO2/SnS2/rGO sensor is 8.91 to 10 ppm HCHO (100 C-degrees), which is about 2.6 and 1.8 times higher than that of the SnO2 and SnO2/SnS2 sensor (200 C-degrees), respectively. The SnO2/SnS2/rGO sensor is also sensitive to ppb level HCHO (1.33 to 100 ppb), exhibits fast response/recovery speed, good reproducibility and long-term stability, and remarkable selectivity. The significant enhancement performance of the SnO2/SnS2/rGO sensor could be ascribed to the synergistic effect of the n-n heterojunction between SnO2 and SnS2, as well as the presence of rGO, which acts as a charge carrier facilitator and enhances the specific surface area boost the high sensing properties. This work provides a practical approach to synthesizing hybrid materials with adjustable micro-morphology, and a promising strategy for designing HCHO sensors with high sensing performance.