Recovering Hydrogen Energy from Photocatalytic Treatment of Pharmaceutical-Contaminated Water Using Co<sub>3</sub>O<sub>4</sub> Modified {001}/{101}-TiO<sub>2</sub> Nanosheets
Yaoyao Wu, Yuqiong Li, Hejing Hu, Guoshen Zeng, Chuanhao Li
Abstract
Photocatalytic water splitting for hydrogen production has been broadly considered as a promising approach to generate renewable energy, while photocatalysis-enabled pollutant degradation is regarded as a sustainable technique for wastewater treatment. Herein, we are aiming to construct a dual-functional photocatalyst system which can degrade pollutants and simultaneously split water to generate hydrogen. We construct the Co3O4 modified {001}/{101}-TiO2 (TC) nanosheets as the efficient dual-functional photocatalyst system. As a p-type semiconductor, Co3O4 construct a p–n junction with TiO2 (n-type). And, the {001}/{101} facet of TiO2 forms an intrinsic surface heterojunction. The unique dual (p–n/surface) heterojunction structure enables the spatial separation of the charge carriers. The holes primarily accumulated on Co3O4 nanoparticles efficiently oxidize the pharmaceutical pollutants including enrofloxacin, ciprofloxacin, and ibuprofen, while the electrons accumulated on {101} facets of TiO2 nanosheet can simultaneously reduce water molecules to generate hydrogen. The effects of Co3O4 loading, catalyst dosage, initial pollutant concentrations, pH values, and coexisting ions on the photocatalytic activities were systematically investigated. In addition, the photocatalysis mechanism is insightfully investigated. This study offers a novel strategy to recover energy stored in wastewater.