Visible light active rGO nanosheet encapsulated Pd quantum-sized dots decorated TiO2 nano-spheres for hydrogen gas sensing at low temperatures

Making reliable gas sensors that function at low temperatures is important for safely detecting hydrogen gas. This work proposes sensitising reduced graphene oxide (rGO) nanosheet encapsulated TiO2 nano-spheres (TiO2-NS) with highly sensitive Pd receptors (rGPT-NS). It demonstrates for the first time, hydrogen gas sensing of rGPT-NS under 490 nm visible light conditions at low operating temperatures (25–35 °C) using a low voltage bias (0.1 V). The method suppresses of the electron-hole recombination and creating interfacial nano-Schottky junctions (i.e., heterojunctions) to enhance sensing performances. As a result, chemiresistive based highly responsive, selective, stable, environmentally friendly, and energy-efficient rGPT-NS are synthesised via sol-gel and hydrothermal methods. The fabricated sensing material exhibits high responses of 100.23%, 100.28% and 100.36% with rapid response/recovery (19 s/62 s, 12 s/57 s and 11 s/53 s) towards 500 ppm hydrogen at 25 °C, 30 °C and 35 °C, respectively under 0.1 V and 490 nm visible light.