Solar-light-driven Z-scheme CaF2:Yb3+,Er3+@ZnTiO3/Au/CdS photocatalyst with efficient charge transfer and light utilization for enhanced norfloxacin degradation with simultaneous hydrogen evolution

Abstract

A novel Z-scheme CaF2:Yb3+,Er3+@ZnTiO3/Au/CdS photocatalyst has been prepared. In this system, an excellent up-conversion luminescent agent, CaF2:Yb3+,Er3+, is introduced to broaden the light response range. The Au surface plasmon resonance effect endows the system with highly efficient charge transfer. The photocatalytic activity of the Z-scheme CaF2:Yb3+,Er3+@ZnTiO3/Au/CdS photocatalyst has been evaluated in the degradation of norfloxacin (NOR) with simultaneous hydrogen production. Some influencing factors, such as solar light irradiation time, sacrificial agent concentration, and number of reuse cycles, are discussed. The emission spectrum and energy conversion mechanism of CaF2:Yb3+,Er3+ have also been studied. The prepared photocatalyst facilitated a significant degree of degradation (92.05%) of NOR and considerable hydrogen production (513.39 μmol/g) under solar light irradiation for 5.0 h. Moreover, it showed high stability in photocatalytic NOR degradation with simultaneous hydrogen production over five cycles. A possible mechanism for photocatalytic degradation of NOR with simultaneous hydrogen production promoted by the Z-scheme CaF2:Yb3+,Er3+@ZnTiO3/Au/CdS photocatalyst is proposed.