Efficient detection of H₂ gas on ZnO-/SnO₂-graphene nanohybrids: experimental and DFT study

In this research, we explored the hydrogen gas sensing properties of microwave-reduced graphene oxide (M-rGO) along with rGO-SnO₂ and rGO-ZnO nanohybrids. These nanohybrids were prepared through a microwave treatment process. Their structural and optical characteristics were analyzed using X-ray diffraction, field emission scanning electron microscopy, and UV-Visible spectroscopy, confirming the successful formation of graphene-metal oxide hybrid structures. The hydrogen gas detection performance of the rGO-SnO₂ and rGO-ZnO nanohybrids was evaluated by subjecting their thin-film sensing platforms to varying concentrations of hydrogen gas (from 50 ppm down to 0.1 ppm) at an operating temperature of 150 °C. The resistance-time behavior of the nanohybrids was monitored under both hydrogen exposure and normal conditions, with measurements taken using a Keithley 2461 source meter. Sensitivity measurements showed maximum values of 22.07%, 22.85%, and 79.39% for M-rGO, rGO-SnO₂, and rGO-ZnO platforms, respectively. These findings were supported by theoretical simulations based on density functional theory (DFT) performed with the Quantum ATK-Synopsis code (version 19.03). The study demonstrates the superior hydrogen sensing capability of the rGO-ZnO nanohybrid.