Highly sensitive sensors based on g-C3N4/In2O3 heterostructure for rapid detection of formaldehyde at low temperature

In this paper, a novel formaldehyde sensor was fabricated by combining two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanosheets with In2O3 nanospheres obtained via a simple solvothermal method. A series of analytical techniques including SEM, TEM, XRD and XPS were implemented to investigate the morphology, structure and elemental composition of the samples. The gas sensing performance of g-C3N4/In2O3 composites was systematically investigated through comparison with that of pure In2O3 nanospheres. By comparison, 20 % g-C3N4/In2O3 sensor showed an optimal response value (59.94) and faster response time (8 s) to 50 ppm formaldehyde at lower operating temperature of 120 °C, which is superior than that of In2O3. Meanwhile, it also showed excellent selectivity and long-term stability over 40 days. The improved sensing properties may be put down to the abundant oxygen vacancy defects and extended charge transfer within the g-C3N4/In2O3 n-n heterojunction and large surface areas. This work furnishes a way to construct formaldehyde sensor for rapid detection under low power consumption.