Jiangfan Sun,Mingcai Yin,Yixian Li,Kaiyue Liang,Yaoting Fan,Zhongjun Li
CdS is a promising photocatalyst and combining MoS 2 with CdS can realize efficient photocatalytic hydrogen production. However, most of the previous researches about MoS 2 /CdS composites focus on hexagonal CdS. Studies on cubic CdS are still rare due to its unstability. Thus in this paper, a ternary composite CdS-MoS 2 /C (abbreviated as CdS-MC, M = MoS 2 , C = activated carbon) was synthesized by facile in-situ liquid phase precipitation of cubic CdS on MoS 2 /C. Based on a series of characterizations, its photocatalytic hydrogen production performance was studied. Under the irradiation of a LED lamp , a high H 2 evolution activity of 879.6 μmol h −1 was achieved for the composite CdS-10%MC, which is 23.3 times that of pure CdS. In addition, its performance is much higher than that of the hexagonal CdS-MC sample (265.6 μmol/h) obtained by heat-treatment of CdS-MC at 400 °C for 1 h under N 2 atmosphere. What’s more, the stability of CdS-MC was investigated and the possible reasons for its unstability were analyzed in detail. To improve the stability, a method of 4-mercaptobenzoic acid (4-MBA) modification was also managed. Finally, possible mechanism for the photocatalytic hydrogen production of CdS-MC was proposed.
Photocatalytic U(VI) extraction is considered as the most promising way to solve the current shortage of uranium resources and radioactive contamination. In this work, O-doped hexagonal-cubic CdS phase heterojunction was constructed by a simple thermal treatment and was successfully used for the photoextraction of U(VI) from water bodies. The samples with different heat treatment temperatures have different phase ratios and oxygen doping amounts. The experimental results show that the CdS heat treated at 350 °C (CdS-350) has the best photocatalytic activity, which can extract 80% of uranium within 120 min (m/v CdS-350 = 0.4 mg/g, C U(VI) = 50 ppm). More interestingly, a systematic mechanistic investigation shows that the extraction process is divided into two steps: i.e., photoelectrons and • O 2 − reducing U(VI) to U(IV) first, followed by photoholes and • OH oxidizing U(IV) to insoluble U(VI) (UO 2 (OH) 2 ). The second step of oxidation allows CdS-350 to avoid photocorrosion, resulting in an excellent recycling performance of only 8% decrease in performance after four cycles.
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