Microwave-assisted hierarchical bismuth oxide worm-like nanostructured films as room-temperature hydrogen gas sensors

Abstract

With a plausible reaction mechanism, a simple and rapid, microwave-assisted chemical synthesis method has been proposed to obtain hierarchical worm-like bismuth oxide (Bi2O3) nanostructured films as an efficient and effective hydrogen (H2) gas sensors. The structural elucidation demonstrates a diffraction peak at 27.94° for [201] directional growth with a lattice fringe distance of 0.31 nm. The Raman shift and photoelectron spectroscopy measurements, additionally, support the formation of the phase pure Bi2O3. Estimated 14.88 m2g-1 specific surface area and 10–20 nm pore-size of as-obtained Bi2O3 evidences its mesoporous character. Among various gases tested, H2 gas endows 50% sensing performance for hierarchical Bi2O3 worm-like film sensors with a considerable response of 42 s and recovery of 83 s for 100 ppm H2 gas concentration at room-temperature, suggesting an importance of proposed method in obtaining the phase pure Bi2O3 film sensors. The H2 gas sensing mechanism has been proposed on X-ray photoelectron spectroscopy results. Finally, an influence of a relative humidity on the Bi2O3 film sensor has demonstrated 32% response at 20% RH with response/recovery time of just 7/10 s, owing to its unique surface architecture, high surface area and mesoporous nature.