The electronic structure regulation improving xylene gas sensing properties in p-type Zn-doped α-Fe2O3 nanoparticles

Xylene is a highly carcinogenic inert gas, and achieving highly selective detection toward xylene gas is crucial for environmental protection and physical health. Herein, α-Fe2O3 nanoparticles doped with different Zn contents (ZF-0, ZF-1, ZF-2 and ZF-3) have been prepared through a feasible solvothermal and subsequent annealing treatment. The successful doping of Zn has been confirmed through EDS, XPS and XRD characterizations. After Zn doping, the baseline resistance in air reduces, the band gap and specific surface area decrease, but oxygen vacancy defects increase for α-Fe2O3 nanoparticles. When applied as gas sensors, all as-prepared α-Fe2O3 samples show typical p-type semiconductor gas sensing behaviors. Especially, the ZF-2 sample with appropriate amount of Zn doping exhibits an excellent xylene gas sensing selectivity. Meanwhile, the ZF-2 sensor shows a high response, fast response/recovery speed, well stability and repeatability and a detection limit of 5 ppm at 240 °C. The acceptor level and oxygen vacancy defects in ZF-2 nanoparticles promote the catalytic oxidation of xylene gas by p-type Zn-doped α-Fe2O3 oxide semiconductors, thereby resulting in better xylene gas sensing performance.