Doping ZnS films with cobalt: Structural, compositional, morphological, optical, electrical, magnetic and photocatalytic properties

Highlights: • Co:ZnS films are synthesized by chemical bath deposition method. • Co:ZnS films show high transmittance in the visible and infrared regions. • Co:ZnS films have paramagnetic behavior. • Co:ZnS is tested for photocatalytic applications. • Co:ZnS films show high photocatalytic efficiency. Co: ZnS (0, 6, 12 and 18 at. -%) nanostructures are mounted on glass substrates by chemical bath deposition (CBD) technique. X-ray diffraction (XRD) analysis shows cubic structure. Compositional study using X-ray photoelectron spectroscopy (XPS) establishes chemical states of Zn²⁺, S²⁻, Co²⁺ and some impurity elements such as C and O. Morphological study reveals the granular shape of the as-grown films. The average optical transmission is greater than 70% in the visible range. A band gap of about 3.70 eV is obtained. A slight enhancement of electrical properties is observed for a doping ratio equal to 12 at.-%. The photocatalytic activity of undoped ZnS and ZnS:(18 at.-% Co) is evaluated under visible light irradiation by following the discoloration of methylene blue. The photocatalytic efficiency achieved by ZnS:(18 at.-% Co) after 4 h of illumination is 69%.