Pt–WO3 porous composite ceramics outstanding for sensing low concentrations of hydrogen in air at room temperature

Abstract Pt–WO 3 porous composite ceramics have been prepared from Pt and WO 3 nanoparticles through pressing and sintering. These ceramics exhibit extraordinary room-temperature sensing capabilities, including high sensitivities, fast response and recovery speeds, and good stability, for low concentrations of hydrogen (at and below 1000 ppm) in air; while for high concentrations of hydrogen (above 2000 ppm) in air, the recoveries in air are only partial in given amounts of time. We propose that for low concentrations of hydrogen, the response results from the reaction of hydrogen with chemisorbed oxygen on WO 3 ; while for high concentrations of hydrogen, hydrogen chemisorption on WO 3 will occur after all chemisorbed oxygen on WO 3 is reacted. The relatively high stability of chemisorbed hydrogen on WO 3 is responsible for the observed partial recoveries. Our results show that Pt–WO 3 composite ceramics are highly competitive for sensing low concentrations of hydrogen in air at room temperature among various metal oxide semiconductor bulk materials.