Clean Water and Sanitation (SDG 6), Climate Action (SDG 13)
Theoretical and experimental insight into the construction of S-Scheme FTO/ NiSe 2 /BiVO 4 photoanode towards an efficient charge separation for the degradation of pharmaceuticals in water Tunde Lewis Yusuf a* , Segun Ajibola Ogundare b , Francis Opoku c , Nonhlagabezo Mabuba a,d a Department of Chemical Sciences, University of Johannesburg, South Africa b Department of Chemical Sciences, Olabisi Onabanjo University, Ago–Iwoye, Nigeria c Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana d Centre for Nanomaterials Science Research, University of Johannesburg, South Africa The increasing contamination of water bodies by pharmaceuticals has become a major environmental concern, with traditional treatment methods often proving ineffective. Photoelectrocatalytic degradation using semiconductor photocatalysts has emerged as a promising alternative, with the aim of using light energy to degrade pollutants. In this manuscript, we present a theoretical and experimental investigation into the construction of an S-scheme FTO/NiSe2/BiVO4 photoanode for the degradation of pharmaceuticals in water. The study focuses on the optimization of the photoanode structure to enhance charge separation and maximize photocatalytic efficiency. The photoanode achieves higher efficiency (76%) in comparison with the pristine BiVO4 (43%) and NiSe2 (17%) for the PEC degradation of ciprofloxacin. This can be attributed to the improved band gap (1.92 eV), low charge transfer resistance (9.6 Ω), reduced flat band potential (0.24 V) and higher charge density (4.86 x 1017 cm–1) resulting from synergic interaction at the heterojunction interface leading fast transition of charge and restraining of recombination of charge carriers. The theoretical modelling of charge density difference displays that the electron accumulation mainly occurs in the NS layer, indicating electron transfer from BVO to NS. The photoinduced carriers are easily spatially separated thanks to the band offset and the built–in the electric field across the NSB interface. The mechanism and the functions of different reactive species are studied, which reveal that the holes mostly dominate the degradation process. The synthesized NSB photocatalyst conforms to an S-scheme heterojunction charge transfer mechanism based on density functional theory, active species capture experiment, and photoelectrochemical detection. We consider the composite suitable for the treatment of water contaminated with pharmaceutical waste.
P25
© The Author(s), 2023
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