Non-Conventional Synthesis and Repetitive Application of Magnetic Visible Light Photocatalyst Powder Consisting of Bi-Layered C-Doped TiO2 and Ni Particles

Abstract

In the current study, a non-conventional application of the magnetron sputtering technique was proposed. A four-step synthesis procedure allowed us to produce a magnetic photocatalyst powder consisting of bi-layered particles with carbon-doped TiO2 on one side, and metallic Ni on the other side. XRD, SEM and EDS methods were used for sample characterization. It was determined, that after the sputtering process optimization, the bandgap of carbon-doped TiO2 was reduced to approximately 3.1 eV and its light adsorption increased over the whole visible light spectrum. The repetitive Rhodamine B solution bleaching with magnetic photocatalyst powder and visible light showed interesting evolvement of photocatalyst efficiency. After the first cycle, Rhodamine B concentration was reduced by just 35%. However, after the second cycle, the reduction had already reached nearly 50%. Photocatalytic bleaching efficiency continued to improve rapidly until higher than 95% of Rhodamine B concentration reduction was achieved (at tenth cycle). For the next ten cycles, photocatalytic bleaching efficiency remained relatively stable. The initial gain in efficiency was attributed to the magnetic photocatalyst particle size reduction from an initial diameter of 100–150 µm to 5 µm. Naturally, the 20–30 times size reduction resulted in a remarkably increased active surface area, which was a key factor for the increased performance.