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 degrees 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.