Interfacial self-assembly of monolayer Mg-doped NiO honeycomb structured thin film with enhanced performance for gas sensing

The relatively low sensitivity, slow response and complicated or energy consuming preparation processes of NiO-based sensors greatly restrict their further application. In this work, monolayer Mg-doped NiO thin film was fabricated via an interfacial self-assemble strategy and a subsequent annealing process. Polystyrene spheres with diameters of about 700 nm were used as templates. The as-prepared monolayer Mg-doped NiO thin film presents a honeycomb structure. The film formation process and possible sensing mechanism of the honeycomb structured Mg-doped NiO thin film are also discussed. Moreover, the film-based gas sensor presents a high selectivity to ethanol gas against other gases. The response ratio of the Mg-doped NiO film sensor to 100 ppm ethanol is 10.4 at 325 °C. This ratio is also much better than some of the previously reported values in literatures. Furthermore, the Mg-doped NiO sensor also shows a significantly enhanced sensing properties in terms of higher selectivity, faster response and recovery time than our honeycomb structured pure NiO thin film. The remarkable properties may be attributed to the honeycomb structure and the Mg doping, which produce more active sites for the gas reaction and adsorption on the surface of the sensing materials. This facile fabrication strategy can be further utilized to prepare other monolayer metal oxide film-based devices.