Constructing N-Pd-O electron bridge between In2O3 nanotubes and g-C3N4 nanosheets to boost explosive gas sensing performance

Portable sensing systems can benefit greatly from low-temperature gas sensors for monitoring low-ppm volatile organic compounds (VOCs), flammable, and explosive gases in enclosed environments. Here, we developed a gas sensor for efficient detection of ethanol and low-concentration H2 at low temperatures, using exfoliated graphitic carbon nitride (g-C3N4) homogeneously loaded with mixed phases of palladium oxide (PdOx) on indium oxide (In2O3) nanotubes to reduce the operating temperature of the sensor and improve the sensitivity, response speed, and detection limit. The optimal working temperature for the sensor based on the heterojunction of g-C3N4/PdOx and In2O3 nanotubes (ECN-PdOx/In2O3) is reduced from 220 °C to 180 °C as a result of logical catalytic state regulation and the introduction of electronic and chemical sensitization by constructing N-Pd-O electron bridge between In2O3 nanotubes and g-C3N4 nanosheets to boost explosive gas sensing performance. Additionally, the gas-sensitive performance investigation revealed that the response of ECN-PdOx/In2O3 to 100 ppm ethanol was up to 320, which was 17 times higher than that of pristine In2O3 and 3.2 times greater than that of PdO-modified In2O3 (PdO/In2O3). Moreover, the sensor based on ECN-PdOx/In2O3 also showed a clear response of 1.56 to 100 ppb H2, while no obvious response of pristine In2O3 and further calculation and analysis obtained that the detection limit of ECN-PdOx/In2O3 for H2 is as low as 23 ppb.