Synthesis and application of Cu-CaTiO3-GO ternary composite: A new visible-light active multifunctional photocatalyst efficient towards antibiotic cefixime degradation and H2 evolution reaction

Abstract

To combat the issues of energy scarcity and environmental pollution, a visible-light responsive, ternary photocatalyst (Cu-CaTiO₃-GO) was fabricated, by photo-depositing Cu nanoparticles over a CaTiO₃-GO binary composite. The physicochemical characteristics of Cu-CaTiO₃-GO were investigated using XRD, HR-TEM, FE-SEM, EDS-mapping XPS, Raman, FT-IR, BET, EIS, UV–vis DRS, and PL techniques. In comparison with pristine CaTiO₃, and binary composites (Cu-CaTiO₃, CaTiO₃-GO), the ternary hybrid exhibited superior photocatalytic activity for H₂ generation as well as antibiotic cefixime (CFX) degradation. Under LED light, the rate of H₂ generation over Cu-CaTiO₃-GO accumulated to 57.69 mmolh⁻¹, while the photodegradation efficiency for CFX reached 94.1 % in 100 min with 53.4 % of TOC removal. The upgraded performance is credited to synergistic effects of Cu NPs (SPR effect), CaTiO₃ (specialized cuboid-like morphology), and GO (high conductivity), co-existing in the trio-hybrid, which resulted in a greatly increased surface area, an expanded spectral response range, a stronger adsorption property, efficient charge migration and separation extent. Ternary catalyst performed well even in the 4 recycling tests (retaining 79.4 % CFX removal and 52.51 mmolh⁻¹ H₂ evolution efficiency). In Cu-CaTiO₃-GO system, the electron transport channel (Cu → CaTiO₃ → GO) with adequate band potentials effectively supports both photocatalytic oxidation and reduction. Photoelectrons are enriched and transferred by plasmonic Cu, and then captured by GO, an e^- sink. This maximizes composite photo redox capability, rapidly generating active radicals (OH), and (O₂^-), degrading CFX to simpler molecules and reducing proton to H₂. The effectiveness of Cu-CaTiO₃-GO was even tested in the real water matrices. Besides, degradation intermediates of CFX were elucidated using LC-MS, and the decomposition pathway was suggested. Finally, the probable photocatalytic reaction mechanism was deduced for both the degradation and H₂ generation processes. The current study proposes a non-noble transition metal-based perovskite-type photocatalytic material for both clean energy generation and wastewater treatment.