In addition, from Figure 4, the Raman intensities of 1-LO and 2-LO are both relatively strong and narrow,

which implies its good crystallinity and ordered structure [28]. Figure 4 Raman spectrum of the typical sample Cd 0.72 Zn 0.26 S. Curves a, b, c, d, and e of Figure 5 show the UV-vis absorption spectra MK-4827 of the as-prepared Cd0.98S, Cd0.9Zn0.1S, Cd0.72Zn0.26S, Cd0.24Zn0.75S, and Zn0.96S, respectively. The absorption edge of Cd1−x Zn x S solid solutions are red-shifted relative to ZnS (Figure 5a), which can be attributed to the incorporation of Zn into the lattice of CdS or entered its interstitial sites (the radii of Zn2+ ion (0.74 Å) is see more smaller than that of Cd2+ (0.97 Å)). The bandgap of Cd1−x Zn x S can be acquired from plots of (αE photon)2 versus the energy (E photon) of absorbed light (α and E photon are the absorption coefficient BIBW2992 and the discrete photon energy, respectively). The extrapolated value (a straight line to the x-axis) of E photon at α = 0 gives absorption edge energies corresponding to E g. From Figure 5b, the bandgap of the synthesized Cd1−x Zn x S are 2.37 eV (curve a), 2.48

eV (curve b), 2.60 eV (curve c), 2.86 eV (curve d), and 3.67 eV (curve e), respectively. The bandgaps of Cd1−x Zn x S are beneficial to absorbing solar light to drive the water splitting reaction. Figure 5 UV-vis absorption spectra (a) and bandgap evaluation (b) from the plots of (αE photon ) 2 vs. E photon. (curve a) Cd0.98S, (curve b) Cd0.9Zn0.1S, (curve c) Cd0.72Zn0.26S, (curve d) Cd0.24Zn0.75S, and (curve e) Zn0.96S, respectively. The photocatalytic hydrogen evolution of the obtained 3D Cd1−x ZnxS photocatalysts under the irradiation of visible light is given in Figure 6. All of the Cd1−x Zn x S photocatalysts show much higher photocatalytic H2 evolution capacity than

that of the sole CdS at visible light irradiation (λ Thymidylate synthase > 420 nm). In addition, the photocatalytic activity of the Cd1−x Zn x S solid solutions is strongly dependent on the composition of the solid solutions. It is improved obviously with the increase of Zn content (x value). When the x value increases to 0.75, the 3D solid solutions photocatalyst has the highest photocatalytic activity. This is because ZnS has a high energy conversion efficiency, it is a good host material for the development of a visible-light-driven photocatalyst by forming solid solutions with a narrow bandgap semiconductor, CdS. The more negative reduction potential of the conduction band of solid solutions would allow for more efficient hydrogen generation than CdS. In addition, the large bandgap and wide valence bandwidth benefit the separation of the photo-generated electrons and holes, and the photocorrosion of the photocatalysts can be reduced effectively. The highest activity probably means that Cd0.24Zn0.75S has an optimum bandgap and a moderate position of the conduction band, beneficial for visible light absorption and photo-generated electron-hole pair separation.