Growth of Ni loaded CdS in nanorods structure for photocatalytic and dye degradation applications under solar irradiation

Abstract

Due to the exponential increase in global energy consumption and the degradation of environmental conditions caused by fossil fuels, it is critical to improve inexhaustible and sustainable resources. Generally, solar energy is one of the clean and environmentally agreeable energy sources. By harvesting solar energy for photocatalysis and considering it as a promising solution for various energy generation applications such as hydrogen production. Herein we are using Cadmium Sulphide and Nickel-doped Cadmium Sulphide in 0.5, 1 and 5 weight percent which act as photocatalyst for water splitting which will eventually produce an enormous amount of Hydrogen (H₂). Cadmium sulphide was prepared through the chemical precipitation method and Ni-CdS by hydrothermal technique. The purity and phase formation were examined by the X-ray diffraction (XRD) and validated via Rietveld refinement by using Full Prof software. The surface morphology and the structure of as-synthesized material were evaluated by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscope (TEM) spectroscopic techniques. Following the results, the Ni-CdS nanocomposite having 1.0 wt% of Ni exhibits the highest H₂ evolution rate of 9 mmolg⁻¹ in 5 h with strong photo-stability, which is about 50 times higher than that of CdS. The material was tested to degrade organic dye for its photocatalytic operations. The newly prepared composite materials (CdS-Ni-NiO) were used for the photocatalytic degradation of the methylene blue (MB) dye. Ni(1.0 wt%)-CdS shows an optimal degradation percentage of 95.436 in the presence of artificial solar light in 90 min. Crystal growth mechanism shows the spherical structure of CdS agglomerate to form nanorods structure when doped with Ni metal which is also verified by the TEM images of CdS and Ni-doped CdS. The XPS peaks observed at 854.88 eV and 861.07 eV for Ni²⁺ with an energy separation of 6.18 eV confirmed the existence of NiO with Ni/CdS. The Raman bands of pure CdS and Ni (1.0 wt%)-CdS nanorods were observed at 300 cm^-1 and 293 cm⁻¹ for 1LO phonon and 601 cm⁻¹ and 586 cm⁻¹ for 2LO phonon corresponds. The Ni tuned the CdS band gap from 2.36 to 2.20 eV. The results pave the way for designing multi-component CdS-Ni nano-composites for highly efficient H₂ evolution and other environmental applications.