NiO nanosteps on Ni: wide band gap p-type nanostructure for efficient cold cathode and magnetically separable photocatalyst

Abstract

Pure nickel micro particles were chemically treated with various concentrations of NaOH and were subsequently annealed in 800 °C. The dimensions of the resulting nanosteps were tuned by simply varying the annealing time durations. Formation of Ni-NiO composite phase was confirmed by x-ray diffraction studies. The morphology of the as-prepared samples was investigated by field emission scanning electron microscope whereas the transmission electron microscope revealed the Ni core NiO shell structure of the samples. The NiO nanosteps showed much improved field emission properties compared to pure Ni micro particles and pure NiO powder synthesized by simply annealing the Ni particles. Finite element based simulation studies revealed strong enhancement of the electric field in the NiO nanostep samples and the simulated results were compared with the experimental outcome. The photocatalytic activities of the as-prepared samples were also investigated, which showed that Ni-NiO nanosteps is a magnetically separable photocatalyst.