Study On Preparation And Performance Of Graphene Carbon Nitride Composites Photocatalysts

The rapid development of society and economy has caused serious problems such as the declining of traditional energy sources and environmental pollution.As a result,human society faces two major challenges in energy development and environmental pollution.Generally,water pollution is main caused by contaminants of heavy-metal ions and organic pollutants,such as.hormones,dyes,pesticides,and perfluorinated organic compounds（PFOCs）.Among them,the organic pollutants in wastewater exhibit high toxicity,carcinogenicity and refractory degradation,which poses a great threat to human health.Therefore,it is possible to develop a new direction for removing organic pollutants in water and obtaining clean energy（such as H₂）,which will enable the simultaneous energyization of pollution resources.Wherefore,it provides new ideas for simultaneously solving energy and environmental issues.Therefore,in this article,we systematically discuss the application of B-CN/CNS composite nonmetallic catalysts in photocatalytic hydrogen production and realize simultaneous photodegradation of organic pollutants and photocatalytic hydrogen generation from water splitting by using the GQDs/TCN composite catalyst.This paper by using the CN and CNS catalyst obtained from different precursors（thiourea and melamine）by calcination,a series of different ratios of B-CN/CNS composite catalysts were synthesized by combined the CNS with CN functionalized by benzoic acid（B-CN）.Systematically studying the effect of the structure and properties of recombination on photocatalytic activity,through a series of experiments,when the composite proportion of B-CN is 10%（10%B-CN/CNS）,the photocatalytic hydrogen production efficiency is the highest.The photocatalytic hydrogen production rate is 1.96 and 1.76 times that of pure CNS and CN-U/CN-T obtained by calcination,the hydrogen production rate is 0.4915 mmol·g^-1·h^-1.Based on the good electron transport ability and upconversion effect of graphene quantum dots,we try use solvothermal methods to combine GQDs with TCN（CNS/Mn-N-TiO₂）,the introduction of GQDs can effectively improve the catalytic performance of the composite catalyst.And the 5%GQDs/TCN-0.4 has the best photocatalytic activity,in the p-nitrophenol（4-NP）solution system the photocatalytic hydrogen production efficiency was 0.8735 mmol·g^-1·h^-1,and the corresponding p-nitrophenol（4-NP）removal efficiency was 88.5%.At the same time,in order to study the effect of different organic pollutant systems on the hydrogen production rate,we also studied the photocatalytic decomposition of hydrogen produced in the solution system of ciprofloxacin（CIP）and diethyl phthalate（CIP）.And this paper investigate the synergistic photocatalytic mechanism to explain the effects of different organic pollutants on the rate of photocatalytic H₂ production.The present work not only provides an ideal scenario of the combination of photodegradation and photoreduction,but also opens a new avenue to achieve the removal of organic pollutants from wastewater coupled with the simultaneous generation of new energy.