Low concentration H2S detection of CdO-decorated hierarchically mesoporous NiO nanofilm with wrinkle structure

CdO-decorated hierarchically mesoporous NiO nanofilm with wrinkle structure was grown in-situ on ceramic tubes via a simple hydrothermal reaction without any surfactant or template. The as-prepared nanofilm was characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and Brunauer–Emmett–Teller (BET) analyzes. It exhibits a nanoparticulate film with uniformly self-assembled wrinkles. These wrinkles are thin porous nanosheets that are further constructed by subnanometer nanoparticles. Compared with the NiO porous nanowall arrays, the 2.01 mol% CdO-decorated NiO film exhibits not only higher response to part per billion (ppb) levels (0.5–100 ppb) H2S at low temperature (92 °C), but also higher selectivity to other reducing gases compared with pure NiO porous nanowall arrays. The lowest detection limit of the NiO film after CdO decoration decreases down to 0.5 ppb while that of pure NiO is 1 ppb. The mechanism of the enhanced H2S sensing for 2.01 mol% Cd-decorated NiO film is also discussed in detail.