Urea mediated synthesis of Ni(OH)2 nanowires and their conversion into NiO nanostructure for hydrogen gas-sensing application

Synthesis of low cost, scalable, robust, and multifunctional nanomaterials for gas sensing application has been received increasing interest in recent years. Herein, we introduce the urea mediated synthesis of Ni(OH)2 nanowires and their conversion into NiO nanostructure for hydrogen gas-sensing application. The Ni(OH)2 nanowires were synthesized by a facile hydrothermal method, where the urea concentration was adjusted to get desired nanowire morphology. Conversion of Ni(OH)2 nanowires into single phase NiO was done by heat treatment of the as-synthesized product at temperature of 500 °C for 2 h. The morphology, crystal structure, crystallinity, and phase transformation of the products were examined by SEM, HRTEM, XRD, and XPS. Gas sensing properties were measured to various H2 concentrations ranging from 50 ppm to 1000 ppm at different temperatures. Results show that the synthesized NiO nanostructure can be used to detect H2 gas at the low concentrations ranging from 50 ppm to 1000 ppm. The sensor also showed good selectivity to CO, NH3 and CO2 gases.