A new visible-light-induced Z-scheme photocatalytic system: Er3+:Y3Al5O12/(MoS2/NiGa2O4)-(BiVO4/PdS) for refractory pollutant degradation with simultaneous hydrogen evolution

A new visible-light-induced Z-scheme photocatalytic system, Er 3+ :Y 3 Al 5 O 12 /(MoS 2 /NiGa 2 O 4 )-(BiVO 4 /PdS), is designed and prepared by using hydrothermal and mixed-calcination methods And the prepared samples are characterized by X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) and UV–vis absorption spectra. The photocatalytic activity is evaluated towards Orange G degradation with simultaneous hydrogen evolution under visible-light irradiation. The photocatalytic experiments indicate that the Er 3+ :Y 3 Al 5 O 12 /(MoS 2 /NiGa 2 O 4 )-(BiVO 4 /PdS) as photocatalyst displays very high photocatalytic activity. It can be ascribed to two sides. One is the use of Er 3+ :Y 3 Al 5 O 12 offering ultraviolet-light to activate the wide-band gap NiGa 2 O 4 . Another is the construction of Z-scheme system between NiGa 2 O 4 and BiVO 4 which can result in a more efficient separation of photoexicited charge carriers, thus endowing it with much powerful oxidation and reduction capabilities. Moreover, the reusability study shows that the prepared photocatalyst can be effectively recycled for three repetitive cycles without an apparent deactivation. In addition, the possible Z-scheme mechanism of Er 3+ :Y 3 Al 5 O 12 /(MoS 2 /NiGa 2 O 4 )-(BiVO 4 /PdS) is also proposed, and further evidenced by photoluminescence (PL) spectra. The present work not only designs a new photocatalytic system but also well applies in photocatalytic degradation of refractory pollutant with simultaneous hydrogen evolution.