Simultaneous photocatalytic degradation of ibuprofen and H2 evolution over Au/sheaf-like TiO2 mesocrystals

Abstract

Considerable effort has been devoted to the efficient degradation of pharmaceuticals and personal care products (PPCPs), while the chemical energy in these processes has been widely overlooked. In this study, we demonstrated the simultaneous hydrogen production and ibuprofen degradation through heterogeneous photocatalysis. By anchoring Au nanoparticles (NPs) on the (101) surface of sheaf-like TiO2 mesocrystals with [001] orientation, efficient charge separation is achieved, which is essential for the photocatalytic redox reactions. XPS analysis showed that the binding energies of Ti 2p and O 1s indicated no shift after Au addition. Peaks observed at 81.8 and 85.5 eV due to Au 4f7/2 and Au 4f5/2 of metallic gold on the surface of Au/meso-TiO2, confirmed the formation of Au NPs. The as-synthesized anatase TiO2 mesocrystals are composed of small nanocrystals with a size of 8 nm and exhibit the uniform sheaf-like morphology along [001] orientation. As expected, the 1 wt% Au/TiO2 mesocrystals shows the largest photocurrent density, highest H2-evolution rate, and fastest photodegradation rate of ibuprofen under simulated sunlight irradiation among all the studied catalyst. Furthermore, the effect of solution pH, common anions (Cl−, NO3−, and SO42−) and cations (Na+, K+, and Ca2+) on photocatalytic H2 evolution and degradation of ibuprofen were individually investigated and discussed. A mechanism for the simultaneous photocatalytic hydrogen generation and degradation of ibuprofen has also been proposed. This work opens up new opportunities for the development of energy efficient techniques for PPCPs degradation.