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We report herein a means of transforming TiO 2 nanotube arrays (TNAs) from an amorphous state to an anatase crystal state (denoted as ∗ TNAs), and present a single-step synthetic route for preparing CdS quantum dots (CdS QDs) as well as reduced graphene oxide (rGO) through gamma-ray irradiation. The as-prepared ∗ TNAs, CdS QDs, and rGO, which had all been subjected to gamma-ray irradiation, were then assembled together to produce the desired heterojunction (denoted as CdS QDs/rGO- ∗ TNAs). X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), ultraviolet/visible diffuse-reflectance spectroscopy (UV/Vis DRS), Fourier-transform infrared spectroscopy (FTIR), micro-Raman spectrometry (RS), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) have been applied to characterize the appearance and performance of this photocatalyst. The photocatalytic activity of CdS QDs/rGO- ∗ TNAs towards ethylene degradation has been measured by placing it in a simulated cold-storage environment, the temperature and humidity of which were set at about 3 ± 1 °C and 75–90%, respectively. The results showed that the rate constant ( K ) of ethylene degradation could reach up to 1.07 × 10 −3  min −1 with CdS QDs/rGO- ∗ TNAs, as compared to 2.30 × 10 −4  min −1 with ∗ TNAs and 6.25 × 10 −4  min −1 with CdS QDs- ∗ TNAs, indicating that the constructed CdS QDs/rGO- ∗ TNAs constitutes a promising photocatalyst for ethylene removal in a cold storage environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • NiS/rGO/Cd 0.3 Zn 0.7 S photocatalysts prepared by facile hydrothermal and photochemical methods. • NiS are uniformly distributed on C 0.3 Z 0.7 S nanorods. • The NiS/rGO/C 0.3 Z 0.7 S exhibits excellent photocatalytic H 2 evolution activity of 1058 μmol h−1. • A possible mechanism was proposed based on the synergistic effect of rGO and NiS. Effectively improving the separation efficiency of photoinduced carriers is of crucial importance for the design of photocatalysts with excellent hydrogen evolution activity. Herein, by combining CdZnS nanorods with rGO and further depositing NiS as cocatalysts, the separation and transfer of photoinduced carriers for CdZnS is significantly improved. Without using any noble metals as cocatalysts, the optimal NiS/0.5%rGO/C 0.3 Z 0.7 S exhibits an outstanding H 2 evolution activity of 1058 μmol h−1 under visible light illumination, which is evidently better than that of pure CdZnS nanorods and most CdZnS-based photocatalysts reported previously. Our study indicates that the introduction of rGO can effectively assist the transfer of photoinduced electrons and evenly distributed NiS on the surface, as the active center for H 2 evolution reaction, can easily capture photoinduced electrons to participate in photocatalytic process. Thus, the synergistic effect of rGO and NiS is considered to be the main cause for the improved photocatalytic performance. This work could offer a facile and low-cost strategy for the construction of composite photocatalysts with high-efficiency hydrogen generation activity. [ABSTRACT FROM AUTHOR]