Fig. 4.

a Schema of the one-step preparation of Pt-doped SnO₂-inverted opal films, and b responses comparison of different sensors as a function of CO concentration at 350 °C (insets are the corresponding HRTEM micrographs). Reproduced with permission [103]. Copyright 2010, American Chemical Society. c Responses comparison of different sensors as a function of working temperature to 74 ppm NH₃ gas (the inset is the corresponding HRTEM micrograph of Pt-WO₃-inverted opal films). Reproduced with permission [104]. Copyright 2011, American Chemical Society. d Synthesis of ordered mesoporous WO₃/Pt hybrids. e Gas response of WO₃/Pt-0.5 and WO₃/Pt-0 to different gases (hydrogen, CO, methane, ethanol, ammonia, acetone, benzene, and toluene) at 100 ppm and 125 °C in 55–60% RH (the inset is an FESEM image of the crystalline WO₃/Pt-0.5 viewed from the top surface). Reproduce with permission [56]. Copyright 2018, Wiley–VCH