A facile chemical synthesis of nanoflake NiS 2 layers and their photocatalytic activity.

A single-phase and crystalline NiS 2 nanoflake layer was produced by a facile and novel approach consisting of a two-step growth process. First, a Ni(OH) 2 layer was synthesized by a chemical bath deposition approach using a nickel precursor and ammonia as the starting solution. In a second step, the obtained Ni(OH) 2 layer was transformed into a NiS 2 layer by a sulfurization process at 450 °C for 1 h. The XRD analysis showed a single-phase NiS 2 layer with no additional peaks related to any secondary phases. Raman and X-ray photoelectron spectroscopy further confirmed the formation of a single-phase NiS 2 layer. SEM revealed that the NiS 2 layer consisted of overlapping nanoflakes. The optical bandgap of the NiS 2 layer was evaluated with the Kubelka-Munk function from the diffuse reflectance spectrum (DRS) and was estimated to be around 1.19 eV, making NiS 2 suitable for the photodegradation of organic pollutants under solar light. The NiS 2 nanoflake layer showed photocatalytic activity for the degradation of phenol under solar irradiation at natural pH 6. The NiS 2 nanoflake layer exhibited good solar light photocatalytic activity in the photodegradation of phenol as a model organic pollutant.