Microwave-assisted synthesis of Fe-doped NiO nanofoams assembled by porous nanosheets for fast response and recovery gas sensors

Fe-doped NiO, a type of p-type gas sensor, has received wide attention for its low cost, environmentally friendliness and excellent gas-sensing performance. However, the operating temperature of Fe-doped NiO is too high (300 °C -500 °C). This study attempts to investigate the possibility of Fe-doped NiO working in relatively low temperature regions. A type of NiO nanofoam assembled by porous nanosheets was synthesized through a normal pressure microwave solvent thermal method by a domestic microwave oven, and Fe doping with different doping concentrations was investigated systematically. The gas-sensing performance was tested at a relatively low temperature (200 °C -280 °C). We found that the Fe-doped NiO still had a good gas-sensing performance, even at a relatively low temperature. In detail, the NiO nanofoams with 3 at% Fe-doping concentration were proven to have the best gas sensing characteristics (the response was 12-100 ppm ethanol at 280 °C), and an especially fast response and recovery (the response time and the recovery time was 1 s and 3.6 s, respectively). The study promoted the research regarding the gas sensing characteristics of Fe-doped NiO at a relatively low temperature.