Ultrathin two dimensional (2D) materials have triggered extensive interest for their exceptional properties and potential applications. Herein, atomic layer graphitic carbon nitride (g-C3N4) was obtained by a simple ultrasonic exfoliation approach, and cadmium sulfide (CdS) nanoparticles were successfully grown on these ultrathin g-C3N4 nanosheets (UCNNS) via a facile solvothermal method. The as-prepared UCNNS-CdS nanocomposite exhibits significantly enhanced photocatalytic activity for methyl orange (MO) degradation under visible light irradiation. The enhancement of the photocatalytic activity should be attributed to the well-matched band structure and intimate contact interfaces between the UCNNS and CdS, which lead to the effective transfer and separation of the photogenerated charge carriers. The mechanism for the photodegradation of MO by the composite was also investigated in this study. This study highlights the potential applications of atomic layer g-C3N4 based photocatalysts, and we hope our work may provide a new insight for the construction of photocatalysts with efficient visible light activity.

The facet-dependent photocatalytic performance of ZnO is still controversial, for the reason that ZnO samples with different high energy facets are hard to prepare. In this paper, three kinds of ZnO with different facet exposures, including {0001}, {101̅1}, and {101̅0} facets, were prepared by a scalable solvothermal method without using any crystal seeds, environmentally harmful chemicals, or severe reaction conditions. The morphologies of ZnO were gradually varied from prism to polyhedron with the increase of ethylene glycol volume fraction. Meanwhile, the predominant exposed facets changed from {101̅0} to {101̅1}. Increasing the volume fraction of ethylene glycol in the mixture solution further, the ZnO spheres formed, where the {0001} facet is predominantly exposed. The formation mechanism for different ZnO geometric structures and their facet-dependent photocatalytic performances were explored in detail, which indicates that the photocatalytic performance is dependent on the crystal facet exposures in the order {0001} > {101̅1} > {101̅0}. Efforts were made to explain the facet-dependent photocatalytic activities basing on the related X-ray photoelectron spectroscopy and atomic stacking model of various exposed surfaces.

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In this paper, Bi 2 WO 6 was, for the first time, utilized as crystal seeds to fine control the ratio of ZnO polar facets under a mild condition. The structure and photocatalytic properties of the ZnO were investigated by powder X-ray diffraction, Raman scattering measurements, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV−vis diffuse reflectance spectroscopy, total organic C analyzer, Brunauer−Emmett−Teller surface areas, and electrochemical workstation. It was found that ZnO architectures were gradually changed from nanorods to nanosheets after adding a certain amount of Bi 2 WO 6 crystal seeds, which led to the change of the ratio of ZnO polar facets. The formation mechanism for this ZnO and the effect of ZnO polar facets on the photocatalytic activity are explored in detail. We find that the nucleation and growth rates of ZnO are controlled by adjusting the quantity of the crystal seeds. Besides, photocatalytic activity of the samples tuned by Bi 2 WO 6 crystal seeds was compared. The ratio of ZnO polar facets is the main factor influencing the photocatalytic activity. The results clearly demonstrate that the sample with a higher proportion of Zn-terminated (0001) and Oterminated (0001̅ ) polar facets is beneficial to enhance photocatalytic activity.