Synthesis of porous In2O3 microspheres as a sensitive material for early warning of hydrocarbon explosions

Efficient detection/monitoring of low-concentration C1-C3 aliphatic hydrocarbons (e.g., methane) is a challenging task, mainly due to their intrinsically low chemical reactivity and thereby weak sensing response. Herein we report the template-free synthesis of porous nanoparticle-assembled In2O3 microspheres that can serve as a highly sensitive material for C1-C3 detection. In particular, porous In2O3 microspheres with a BET surface area of 57 m(2) g(-1) are prepared through simple thermal treatment of an indium glycerolate precursor. The gas-sensing properties of the porous In2O3 material are evaluated by a series of C1-C3 hydrocarbons including methane (CH4), ethane (C2H6), propane (C3H8), ethylene (C2H4) and acetylene (C2H2). The porous In2O3 material has the ability to detect these gases with a rapid response (<10 s) in a wide concentration range from 200 ppm to 50 000 ppm (the lower explosion limit of methane). In the testing range, the logarithm of response shows a good linear dependency on the logarithm of gas concentration, demonstrating that the porous In2O3 material may be used for quantitative detection of C1-C3 hydrocarbons. Given the rapid response and high sensitivity below the explosion limit, this porous In2O3 material is promising to provide earlier warning against the explosion risk of hydrocarbon compounds.