High-Performance Sulfur Dioxide Gas Sensor Based on Graphite-Phase Carbon-Nitride-Functionalized Tin Diselenide Nanorods Composite

In this paper, a composite of tin diselenide (SnSe2) functionalized by graphite-phase carbon nitride (g-C3N4) was successfully prepared by a hydrothermal method, and was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). These microstructure characterization results verified the successful synthesis of a multilayer g-C3N4/rod-shaped SnSe2 composite. The gas sensitivity results showed that when the g-C3N4 ratio was 30%, the g-C3N4/SnSe2 composite sensor had the highest response (28.9%) at 200 °C to 20 ppm sulfur dioxide (SO2) gas, which was much higher than those of pristine g-C3N4 and SnSe2 sensors at the optimum temperature. A series of comparative experiments proved that the g-C3N4/SnSe2 composite sensor demonstrated an excellent response, strong reversibility and good selectivity for ppm-level SO2 gas detection. The possible SO2 sensing mechanism was ascribed to the heterostructure between the n-type SnSe2 and n-type g-C3N4 nanomaterials. Furthermore, we also proposed the influence of the special structure of the g-C3N4 functionalized SnSe2 composite on the gas-sensing characteristics.