Study on the corrosion resistance of electrodeposited NiW/TiO2 composite coating and its application in methylene blue degradation in simulated wastewater

NiW/TiO₂ composite coatings were electrodeposited on the surface of Q235B steel to investigate the effect of different TiO₂ particle concentrations on the deposition rate, thickness, chemical composition, and surface morphology of the composite coatings. The corrosion resistance of the NiW/TiO₂ composite coatings and their photocatalytic degradation of methylene blue in simulated wastewater were examined and verified. The NiW/TiO₂ composite coating electrodeposited from a plating solution with 15 g/L TiO₂ particle exhibited the fastest deposition rate (402 mg/h) and the largest thickness (23.92 μm). All electrodeposited NiW/TiO₂ composite coatings comprised C, Ti, Ni and W, with granular surface morphology. Increasing the TiO₂ particle concentration in the plating solution enhanced the mass transfer rate of Ni ions, thereby increasing the Ni and Ti contents in the composite coating. However, at an excessive TiO₂ particle concentration of 20 g/L, the viscosity increased and the transfer rate of particles and nickel ions decreased, resulting in a decrease in the Ni and Ti contents in the composite coating. Among all NiW/TiO₂ composite coatings, the NiW/TiO₂ composite coating electrodeposited from a plating bath containing 15 g/L TiO₂ particle demonstrated optimal corrosion resistance with the most positive corrosion potential (-0.533 V) and the lowest corrosion current density (8.6×10⁻⁶ A/cm²). The electrodeposited NiW/TiO₂ composite coatings effectively degraded the methylene blue in the simulated wastewater, achieving an optimal degradation efficiency of 60.7 %.