Facile synthesis of three-dimensional hierarchical NiO microflowers for efficient room temperature H2S gas sensor

Abstract

In this work, we have demonstrated a facile hydrothermal method to synthesize three-dimensional hierarchical NiO microflowers. The structures and morphologies of the samples were investigated by different kinds of techniques, including X-ray diffraction, field emission scanning electron microscopy and energy dispersive spectrometer. These characterizations indicated that these three-dimensional NiO microflowers were well crystallized, having a uniform flower-like morphology with dimensions of 4–6 μm, which consist of many nanorods. The three-dimensional hierarchical NiO microflowers exhibited excellent room-temperature H2S gas-sensing performance, including a response as high as 8.8, a short response time of 3.5 s to 97.0 ppm H2S, and a low detection limit of 485 ppb. The excellent gas-sensing performance of these three-dimensional hierarchical NiO microflowers sensors to H2S could be ascribed to the porous structures in the unique microflowers with a large specific surface area, which benefit H2S molecules to adsorb/desorb onto/from the three-dimensional hierarchical NiO microflowers surface as well as the electron transfer. The formation of NiO microflowers and their possible H2S-sensing mechanism are discussed in detail.