Template-less surfactant-free hydrothermal synthesis NiO nanoflowers and their photoelectrochemical hydrogen production

A facile direct surfactant-free template-less hydrothermal method is employed for the growth of high surface-area NiO nanoflowers made up of complex and assembled nanosheets network. Field emission scanning electron microscopy revealed that each nanosheet is about 50-60 nm thick. Detailed structural analysis reveals single-crystalline nature of NiO nanoflowers with cubic crystal structure. The optical absorption bands in the wavelength range of 350-800 nm illustrated in terms of ligand field theory. The photoelectrochemical (PEC), water splitting performance on the NiO nanoflowers were also investigated.