Controlled synthesis of porous Ni-doped SnO2 microstructures and their enhanced gas sensing properties

Porous Ni-doped SnO2 microspheres and microcubes were obtained via a facile chemical solution route followed by calcination and acid-washing process. Their structural and morphological evolution was characterized using a range of techniques. The process of inducing porosity began with crystalline single-phase NiSn(OH)6 precursors formed by the co-precipitation of metal ions from an aqueous solution. Thermal decomposition of the precursors led to an intimate mixture of cubic phase NiO and tetragonal phase SnO2. The Ni-doped SnO2 microspheres and microcubes were obtained after a simple acid-washing process. A decomposition–aggregation–dissolution process was proposed to explain the formation of these structures. The gas-sensing properties of the as-prepared porous Ni-doped SnO2 microspheres and microcubes for toxic volatile organic compounds, such as formaldehyde, ethanol, benzene, methanol, acetone, and toluene, were investigated. The enhanced sensing performance of the porous Ni-doped SnO2 microspheres was demonstrated. The detection limits of formaldehyde and ethanol were approximately 0.17 and 0.09 ppm (signal-to-noise ratio, S/N = 3), respectively. The enhanced sensing performance of the porous Ni-doped SnO2 microspheres was attributed to their Ni-dopant, unique porous structure and large surface area.