WO3 nanofibers anchored by porous NiCo2O4 nanosheets for xylene detection

In this work, porous NiCo2O4 nanosheets anchored on the surface of 1D WO3 nanofibers were synthesized via a hydrothermal route followed by a facile chemical deposition treatment. The as-obtained products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Teller analysis. The porous NiCo2O4 nanosheets grew on the surface of WO3 nanofibers with an intimate contact between their interfaces, leading to the formation of p-n heterojunctions and an increase of surface area. Compared with the pristine WO3 nanofibers and NiCo2O4 nanosheets, the NiCo2O4/1D WO3 nanocomposite exhibited the highest response to xylene (R-g/R-a = 15.69 toward 100 ppm). Moreover, the NiCo2O4/1D WO3 nanocomposite also demonstrated outstanding selectivity, excellent stability and low detection limitation (similar to 5 ppm) to xylene vapor. The main mechanism for the enhanced gas-sensing properties of NiCo2O4/1D WO3 nanocomposite was attributed to the unique porous structures and p-n heterojunctions between NiCo2O4 nanosheets and WO3 nanofibers. The excellent gas-sensing properties of NiCo2O4/1D WO3 nanocomposite make it a good candidate as a gas-sensing material for the practical application in xylene detection.