Surfactant-free synthesis of 3D hierarchical flower-like NiO nanostructures with enhanced ethanol-sensing performance

Different morphologies hierarchical flower-like Nickel oxide nanostructures were fabricated by changing the volume of ammonia (Va = 1, 4, and 8 ml) under a template-free and low-cost hydrothermal method and subsequent calcinations. The nanoflowers were composed of two-dimensional (2D) nanosheets. The sensor based on the samples of Va = 8 exhibited the most excellent gas-sensing performance to ethanol. Moreover, a possible growth mechanisms were also proposed. The facile preparation method and the improved properties derived from the three-dimensional structures are significant in the synthesis and future applications of functional nanomaterials.