The effects of Co doping on the gas sensing performance of In2O3 porous nanospheres

Gas sensor constructed with metal oxide semiconductor (MOS) has attracted a growing concern owing to its feasibility for rapid detection of various harmful and pollutant gases . However, the sensors made of pure MOS usually suffer from the drawbacks of high working temperature, low sensitivity and poor selectivity. Herein, we propose a Co-doping strategy to upgrade the gas sensing performance of In 2 O 3 . To expound it, Co-doped In 2 O 3 porous nanospheres (Co-In 2 O 3 PNSs) with the diameter of ∼120 nm was prepared from home-made In(OH) 3 NSs via a soaking-lyophilization-calcination method and their sensitive performance towards several volatile organic compounds (VOCs) was investigated in detail. Compared to pure In 2 O 3 sensor, the best Co-In 2 O 3 sensor (with optimized 0.5 mol% Co) exhibited outstanding improvements in triethylamine (TEA) sensing performance, especially including lower optimal working temperature (OWT: 220 °C vs 320 °C), higher response (R a /R g : 3500 vs 60 for 10 ppm TEA), and better selectivity (selectivity coefficient S TEA /S ethanol : 400 vs 1850). Besides, an interesting selectivity transformation from ethanol to formaldehyde was also observed after Co doping. These improvements of Co-In 2 O 3 PNSs were mainly attributed to their reduced crystallite size, increased oxygen vacancy concentration, narrowed bandgap, as well as upshifted Fermi level , whose mechanism was discussed.