Impact of Cu particles on adsorption and photocatalytic capability of mesoporous Cu@TiO2 hybrid towards ciprofloxacin antibiotic removal

In this study, Cu@TiO2 hybrids consisting of Cu nanoparticles and mesoporous TiO2 nanoaggregates have been successfully synthesized through a simple reduction method. The Cu2+ concentration can not only engineer the mass ratio of Cu specie in the hybrids, but also tailored the size of Cu particles during this synthesis. The adsorption and photocatalytic performance towards degrading ciprofloxacin of the as-synthesized Cu@TiO2 hybrids were determined by the mass ratio as well as the Cu particle size of Cu@TiO2 in the hybrids. It was found that the Cu@TiO2 hybrid with low Cu content promoted photocatalytic performance, while high Cu content improves the adsorption efficiency. Among the as-prepared Cu@TiO2 samples, the 0.1-Cu@TiO2 sample with Cu particle content of 0.1 wt% displayed the best charge separation and transfer efficiency for photogenerated electrons and holes, and accordingly, presented the best photocatalytic efficiency, which is around 3 times higher than that for pure TiO2. In contrast, 10-Cu@TiO2 with 10 wt% Cu showed the highest adsorption capability (888.57 mg/g, about 5 times larger than that of TiO2), since it had the most negative zeta potential, although its Brunauer-Emmett-Teller surface area was less than that of the pure TiO2 material. This work has not only developed a facile approach to prepare Cu-based hybrids, but also reveals how Cu@TiO2 hybrids can be tailored and optimized for adsorption and photocatalytic removal of antibiotic pollution.