Preparation And Photocatalytic Properties Of CDs/BiOI Composite Materials

Along with the development of the industry,the pullution is more and more serious,especially the water pollution has threaten the human health,so it is very urgent to use green technology to remove pollutants.Semiconductor nanomaterials can reduce oxidize toxic pollutants under solar light irradiation,hold great prospects for renewable energy substitutes and environmental protection.To utilize solar light effectively,the quest for highly active photocatalysts working under visible light has always been the research focus.The properties of semiconductors are dependent on their morphologies and compositions as well as structures,and this also offers the guidelines for design of highly-efficient photocatalysts.In this study,BiOI,CDs and CDs/BiOI composite photocatalytic materials were prepared.The structure,morphology and properties of the composites prepared under different conditions were characterized by X-ray Diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,specific surface area（BET）,Fourier transform infrared spectroscopy（FT-IR）,Raman spectroscopy,UV-visible（UV-vis DRS）.The photocatalytic performance of CDs/BiOI composites prepared under different conditions on Methyl orange degradation was studied.And the mechanism of photocatalytic degradation was discussed preliminarily.Using Bi（NO₃）₃ and KI as raw materials,the flower like Bi OI photocatalytic materials were prepared by simple hydrolysis conversion method without template and ultrasonic.It was found that the feeding sequence,hydrolysis time and temperature had no significant effect on the phase structure of BiOI,but had a great influence on the morphology of the product.The carbon dots were prepared by alkali assisted ultrasonic method with glucose as carbon source.The CDs/BiOI composites were prepared by the method of hydrolysis and transformation.The different composite amount of CDs,the composite time and the composite temperature had no effect on the structure of the composites,but had an influence on the morphology of the composites.CDs in the CDs/BiOI composite material is distributed on the surface and edge of the Bi OI layer.IR and Raman studies showed that the interaction between CDs and BiOI in the prepared CDs/Bi OI composites occurs.The degradation of methyl orange over CDs/BiOI composites prepared by different composite amount of CDs,the composite time and the composite temperature were studied.The photocatalytic properties of the CDs/BiOI-1 composites prepared with the composite CDs of 0.1%and the composite time 2h at room temperature were the best,and reached to 59.97%under the visible light irradiation 1.5h.The photocatalytic efficiency of the prepared CDs/BiOI-2 composite was the highest and reached 72.88%under the visible light irradiation 1.5h.The results showed that the photocatalytic degradation of methyl orange by CDs/BiOI was higher than that of the sum BiOI and CDs,respectively,under visible light irradiation.In the degradation of methyl orange over CDs/BiOI composites,the common role of the electron and the hole exist,while electrons play a leading role.The high photocatalytic performance of CDs/BiOI photocatalytic materials are due to the combination of CDs and Bi OI.Under visible light irradiation,BiOI obtained photogenerated electron-hole pairs,the composite of CDs and BiOI can effectively inhibit the recombination of electron and hole in the BiOI.