| Graphite-like carbon nitride?g-C3N4?,as a metal-free two-dimensional layered polymer n-type semiconductor,has the advantages of simple synthesis method,abundant raw materials,non-toxic,good chemical stability,etc.In recent years It has received extensive attention in the field of photocatalytic decomposition of hydrogen evolution and degradation of water pollutants.However,the bulk g-C3N4?Bulk g-C3N4,BCN?prepared by the traditional direct high-temperature calcination method has a small specific surface area,easy photo-electron-hole recombination,and a narrow visible light response range.These problems seriously restrict the photocatalytic activity of BCN.Therefore,various methods,such as synthesis method control,doping modification and multi-component compounding,are imperative and have achieved many results.In this paper,melamine is used as the raw material to synthesize massive g-C3N4 by direct high-temperature calcination,followed by secondary calcination,and it is modified by ultrasonic in a polar solvent,and on this basis,it is modified by in-situ,hydrothermal,compounding,etc.Further modification is carried out to further increase its specific surface area,reduce the photogenerated electron-hole recombination rate,and increase its photoresponse range.?1?In this paper,melamine was used as raw material to directly synthesize bulk g-C3N4 by high-temperature calcination again Subsequently,the layers of BCN were separated by ultrasonic stripping in anhydrous ethanol solution to obtain less-layered g-C3N4 nanosheets?CNS?.Scanning Electron Microscopy?SEM?,Transmission Electron Microscopy?TEM?,and Atomic Force Microscopy?AFM?showed success CNS were synthesized?each layer with a thickness of about 2 nm?.The results of BET and PL tests showed that the synthesized CNS had a high specific surface area(64.25 m2·g-1)was 9.1 times that of BCN(7.03 m2·g-1)and had a lower fluorescence intensity.Testing the photocatalytic water resolution of hydrogen under simulated sunlight showed that the hydrogen production rate of CNS was 0.64 mmol·h-1·g-1,which is 4.7 times that of BCN.?2?Few-layer g-C3N4 nanosheets loaded with cubic phase CdS were synthesized by in situ deposition in a sulfur-rich environment.Composites?CNS-CdS?.The BET test results show that the optimum ratio of composites?CNS-CdS-1:3?reached 156.50m2·g-1 which is 22.2 times that of BCN,and the PL test results showed that CNS-CdS-1:3 has the lowest fluorescence intensity and the photoelectric test results show that CNS-CdS-1:3 at 475 nm.The photocurrent conversion efficiency?IPCE?at 475nm is up to 59.6%,while the apparent quantum efficiency?AQE?at 475 nm reached13.83%.The results of testing photocatalytic water resolution of hydrogen under simulated solar irradiation showed that the hydrogen production rate of CNS-CdS-1:3was 2.34 mmol·h-1·g-1,which is 3.5 times that of CNS.CNS loading with CdS increased the more multiple photocatalytically active sites,reducing the complexation rate of photogenerated electron-hole pairs,and due to the simultaneous properties of CdS in the visible region also.The visible photocatalytic activity of CNS was enhanced.Therefore,the CdS doped CNS exhibited better photocatalytic performance.?3?Hexagonal?-Fe2O3 was synthesized from melamine and ferric chloride by microwave-assisted hydrothermal method and passed through two stages of High-temperature calcination synthesis of 2D g-C3N4/hexagonal?-Fe2O3 doped composite materials?2DGCN/?-Fe2O3?.The results of the analysis by BET test showed that the best ratio of the composite 2DGCN/?-Fe2O3-5 specific surface area It reached 73.38 m2·g-1 which is 10.4 times higher than BCN.The results based on PL test showed that 2DGCN/?-Fe2O3-5 had low fluorescence intensity.Under simulated sunlight irradiation,the average photocatalytic hydrogen resolution rate of2DGCN/?-Fe2O3-5 per hour of water was 1.30 mmol·h-1·g-1 which is 5.4 times higher than 2DGCN.The physico-chemical characterization of the composite photocatalytic materials with enhanced photocatalytic hydrogenation effect was successfully synthesized.2DGCN/?-Fe2O3,?-Fe2O3 could add more active sites to further enhance its Photocatalytic properties. |
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