Wenjian Fang

Metallic 1T-LixMoS2 co-catalyst enhanced photocatalytic hydrogen evolution over ZnIn2S4 floriated microspheres under visible light irradiation

Lithium intercalated 1T allotropes of molybdenum disulfide/zinc indium sulfide (1T-LixMoS2/ZnIn2S4) composites were synthesized using a two-step hydrothermal method. The as-prepared samples were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance absorption spectra, photoluminescence emission spectra and Raman spectra. The results indicate that the lithium intercalation reaction transforms the MoS2 crystal from the hexagonal structure (2H phase) to the trigonal 1T phase. By introducing metallic 1T-LixMoS2 as a co-catalyst, the photocatalytic hydrogen (H2) evolution activity of the ZnIn2S4 microspheres is significantly enhanced under visible light irradiation. The enhanced photocatalytic activity is mainly attributed to the fact that the metallic 1T-LixMoS2 promotes the efficient separation of the photoexcited electrons and the holes of ZnIn2S4 microspheres because of its high electrical conductivity and high densities of the active sites. The photoexcited electrons of ZnIn2S4 microspheres can not only transfer to the edge sites of 1T-LixMoS2, but also to the basal plane active sites of 1T-LixMoS2. Furthermore, the photocatalytic activity is dependent on the content of 1T-LixMoS2 in the composites. The 2.0 wt% 1T-LixMoS2/ZnIn2S4 sample shows the highest H2 production rate of 332.4 μmol h−1, which is 2.4 times higher than that of bare ZnIn2S4 and 1.3 times higher than that of 2.0 wt% 2H-MoS2/ZnIn2S4, and it remains stable even after three photocatalytic cycling tests.

A visible-light driven novel layered perovskite oxyhalide Bi4MO8X (M = Nb, Ta; X = Cl, Br) constructed using BiOX (X = Cl, Br) for enhanced photocatalytic hydrogen evolution

A novel visible-light responsive layered perovskite photocatalyst Bi4MO8X (M = Nb, Ta; X = Cl, Br) has been successfully constructed using BiOX (X = Cl, Br) via a solid state method. The as-prepared samples were characterized by XRD, SEM, HRTEM, EDS, element mapping, XPS and UV-vis spectra to determine the structures, morphologies and optical properties. Photocatalytic activities were conducted under simulated sunlight as well as visible light and evaluated by the efficiency of hydrogen evolution. Among these photocatalysts, the photocatalytic capability of hydrogen generation for Bi4NbO8X was better than that of Bi4TaO8X (X = Cl, Br), while Bi4NbO8Br showed the best performance for photocatalytic hydrogen production. Moreover, these photocatalysts exhibited excellent activity for hydrogen generation when glycerol was utilized as a sacrificial agent, which could be assigned to its low standard oxidation potential and the number of α-OH groups. Furthermore, we demonstrated that the structural properties of Bi4NbO8Br were beneficial for the mobility of photocarriers. The reason for this can be ascribed to the [Bi2O2]2+ structures with lower twisting degree, as evidenced by the Raman spectra analysis.