Synthesis, characterization and application of palladium and rhodium-doped nio nanoparticles in photocatalytic process

Photocatalysis technology has become a competent method used in the treatment and remediation of harmful and toxic organic compounds. Studies to improve the photocatalysts used in this technology focus on utilizing sustainable energy and saving energy. Scientists aim to produce efficient catalysts that are activated by sunlight energy. Doping metal oxide photocatalysts with dopant materials provides advantages such as improved optical properties of the catalyst and reduced recombination rate, which is important for the catalyst mechanism. In this study, NiO and palladium and rhodium doped NiO nanocatalysts were synthesized for the first time by chemical precipitation method. The photocatalytic properties of photocatalysts were investigated and their structural, chemical, optical, thermal and morphological properties were investigated through XRD, SEM, EDX, TEM FT-IR, PL, DSC methods. Photocatalytic removal efficiency of synthesized NiO, NiO/Pd, NiO/Rh nanoparticles on methylene blue and methyl orange dyes under visible light was investigated through UV-vis spectrophotometer. In the photocatalytic activity studies on the removal of methylene blue and methyl orange dyestuffs of undoped NiO nanoparticles, the percent removal values were obtained as 80.15% and 65.21%, respectively, after 120 minutes. It was observed that the addition of palladium and rhodium to the NiO structures considerably increased the methyl orange and methylene blue removal efficiency under visible light. The methylene blue removal efficiency of NiO/Pd photocatalysts in halogen light environment was measured as 97.52% after 105 minutes and 98.05% after 105 minutes for NiO/Rh photocatalysts. In the removal of methyl orange dyestuff, an anionic dyestuff, in the experiments carried out in visible light, the Pd-doped NiO catalysts reached an efficiency of 98.02% in as little as 15 minutes, and the Rh-doped NiO catalysts reached an efficiency of 97.27% in 15 minutes. In the dyestuffs solutions, optimum values for Pd/NiO and Rh/NiO catalyst loadings were found as 1.5 and 1.2 mg/mL, respectively. The photocatalysts were reused 5 times to test for their reusability, and were found to retain their efficiency after the test. Keywords: dye removal, nanotechnology, NiO, photocatalysis, semiconductor