A facile chemical synthesis of nanoflake NiS₂layers and their photocatalytic activity

Abstract

A single-phase and crystalline NiS₂ 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 NiS₂ layer by a sulfurization process at 450 °C for 1 h. The XRD analysis showed a single-phase NiS₂ layer with no additional peaks related to any secondary phases. Raman and X-ray photoelectron spectroscopy further confirmed the formation of a single-phase NiS₂ layer. SEM revealed that the NiS₂ layer consisted of overlapping nanoflakes. The optical bandgap of the NiS₂ layer was evaluated with the Kubelka-Munk function from the diffuse reflectance spectrum (DRS) and was estimated to be around 1.19 eV, making NiS₂ suitable for the photodegradation of organic pollutants under solar light. The NiS₂ nanoflake layer showed photocatalytic activity for the degradation of phenol under solar irradiation at natural pH 6. The NiS₂ nanoflake layer exhibited good solar light photocatalytic activity in the photodegradation of phenol as a model organic pollutant.