Synthesis, UV response, and room-temperature ethanol sensitivity of undoped and Pd-doped coral-like SnO₂

Coral-like mesoporous SnO₂ was synthesized by controlled hydrolysis of SnCl₄ and subsequent removal of the template by calcination in air. The obtained powder was doped directly with palladium chloride solution. The morphology, crystal structure, specific surface area, and photoelectrical and ethanol gas-sensing properties of undoped and Pd-doped coral-like SnO₂ were investigated. The average crystalline sizes of undoped and Pd-doped SnO₂ were estimated by Williamson–Hall plots to be 10.3 and 10.0 nm, respectively. From the N₂ adsorption–desorption analysis, the pure sample had a surface area 63.3 m²/g with pore size distribution narrowly centered around 5.7 nm. The film sensors based on undoped and Pd-doped SnO₂ exhibited novel photoelectrical properties. The photocurrents of the sensors decreased with increasing UV light intensity. The response of the Pd-doped SnO₂ sensor to 500 ppm ethanol was 35.3 under UV illumination at room temperature. The results demonstrated that Pd doping could achieve room-temperature detection to ethanol under UV light radiation.