| Due to their unique size and structures, low-dimensional nanomaterials oftenpresent different physical and chemical properties. Iodine and bromine are two typicaldiatomic molecules. The structures of one dimensional iodine/bromine chains is totallydifferent from that of bulk materials. The study of the structure transformation andproperties of one dimensional chains can help us to deepen the understanding ofdiatomic system. MoS2is a typical two dimensional material. Due to its excellentcatalytic properties, nano-sized MoS2attracts much attention in recent years. In thiswork, we selected aluminum phosphate molecular sieve (AlPO4-5) and graphene asthe template to synthesize I/Br@AlPO4-5and graphene/MoS2hybrid.In this work, we used vapor diffusion method to synthesize I@AlPO4-5singlecrystals. We test the PL property of the sample. A broad and intense emission band isobserved in the range from550nm to900nm with peak centered at750nm (1.66eV). Insharp contrast, undoped AlPO4-5single crystal, I@AlPO4-5single crystal with low doping concentration and pure iodine particle do not show any visiblephotoluminescence in this energy range. We deduced that the PL arises from the iodinechains. The sample showed obviously anisotropy of PL signal. Both the absorption andemission dipoles are parallel to the axis of the channel, which can be well explained bythe unique one-dimensional configuration of the iodine chains. In the thermal PL test,the variation of PL is corresponding to the dissociation of iodine chains reportedbefore. As the pressure increase, the PL intensity increases obviously from ambientpressure to1.1GPa and then decreases with pressure increasing further, which iscorresponding to the elongation of iodine chains upon compression. The theoreticalsimulation is well agreed with the experimental results.Under the confined environment, bromine can grow into both the molecular chainsand the ionic chains. In previous work, people only studied the effect of pressure onbromine species and the influence of temperature has not been reported before. In thiswork, we test the influence of temperature on bromine species. For the thermal test,the bromine molecules transform into bromine molecular chains at first, and then thebromine molecular chains began to dissociate. The laser heating method testified thatincrease temperature can make the bromine molecules transform to bromine chainsfurther. For the low temperature test, the orientation of bromine molecules changed atlow temperature. The bromine molecules tend to parallel to the channels of AlPO4-5single crystal. As the “lying” molecules are more easily affected by surroundingspecies, the Br3-1chains attract the “lying” molecules under electrostatic interactionsand form a new bromine species.MoS2is a typical two dimensional semiconductor material. Due to its narrow bandgap, MoS2has the potential photocatalytic application under visible light. However,the quick recombination of photoelectron–hole pair is significantly influences itsphotocatalytic activity. Therefore, how to decrease the recombination ofphotoelectrons and holes is the key to improve the photocatalytic performance ofMoS2. In this work, MoS2/RGO hybrid was prepared by using hydrothermal method.The samples were characterized by TEM, High Resolution Transmission electronmicroscopy, XRD and Raman. The MoS2nanoflakes are uniformly and compactly grown on the surface of grapheme. We test the photocatalytic performance of thesamples, which exhibited excellent photocatalytic activity, especially under the VISirradiation. For the VIS photocatalysis, the decomposition of methylene bluemolecules photocatalyzed by MoS2/RGO hybrid was totally complete after75minutesVIS irradiation, which is much better than the current commercial photocatalyst andpure MoS2naonoflakes. MoS2/RGO hybrid also exhibits remarkable photocatalyticstability. This result also proved that it is a good way to enhance the MoS2photocatalytic performance through growing MoS2nanoflakes on the surface ofgraphene. |
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