Preparation And Performance Study Of Three-dimensional Multifunctional Graphene-based Composite Aerogel

The massive discharge of dye wastewater has caused serious environmental pollution problems.In order to protect the ecological environment and maintain the health of organisms and the harmonious development of social economy,it is urgently required to detect and remove dye wastewater.There is an urgent need to develop high-efficiency adsorbents and photocatalysts with high-sensitivity detection and better photocatalytic activity.In this work,a simple one-pot hydrothermal method and chemical reduction self-assembly strategy are used to prepare a three-dimensional multifunctional composite aerogel with excellent SERS activity,adsorption and photocatalytic properties.The main conclusions are as follows:（1）The Ag/g-C₃N₄/RGOA composite aerogel with a multifunctional three-dimensional porous network structure is obtained through the one-pot hydrothermal method and freeze-drying process.The Ag/g-C₃N₄/RGOA#2 composite aerogel exhibits excellent adsorption and photocatalytic performance.For 10 ppm Rhodamine6G（R6G）,the adsorption rate is 44%,and the photocatalytic degradation rate reaches93%under 4h visible light irradiation,and it has good photocatalytic stability.This is mainly due to the synergy photocatalysis effect between Ag NPs,g-C₃N₄ and RGO.The3D porous network structure is conducive to the use of visible light and the transfer of photogenerated electrons.In addition,the Ag/g-C₃N₄/RGOA#2 composite aerogel substrate has excellent SERS activity,and the detection limit is 1×10^-7 M for R6G.The excellent SERS performance is attributed to the electromagnetic enhancement of Ag NPs and the chemical enhancement between g-C₃N₄,RGO and dye molecules.We found that SERS could be used to monitor the adsorption and photocatalytic degradation of dye molecules by the composite aerogel.In this research,the designed multifunctional composite aerogel may be used as a material with potential applications for the detection and removal of dye molecules in wastewater.（2）The 3D multifunctional Ag/MoS₂/RGOA composite aerogels were successfully prepared by a simple one-pot hydrothermal method and chemical reduction self-assembly strategy.The morphology and structure of the composite aerogel were characterized by SEM,TEM,XRD.The surface chemical valence state and element composition were characterized by XPS.The detection limit of Ag/MoS₂/RGOA#2 composite aerogel substrate for methyl orange（MO）is 1×10^-6 M.A large number of"hot spots"can be formed between Ag NPs,and lead to enhanced electromagnetic field.After being excited by light,MoS₂ generates photogenerated electrons and holes,and there is a charge transfer between MoS₂,RGO and dye molecules,which results in a chemical enhancement.Ag/MoS₂/RGOA#2 composite aerogel shows more excellent photocatalytic degradation performance.For the 20 ppm MO solution,the adsorption rate is 33%,and the photocatalytic degradation rate is 95%.Firstly,the photogenerated electrons generated by MoS₂ nanosheets under the excitation of visible light can be transferred to the surface of RGO,which greatly inhibits the rapid recombination of electron-hole pairs,which is confirmed by the PL spectrum and the transient photocurrent curve.Secondly,the LSPR effect of Ag NPs has a promoting effect on the photocatalytic process.Finally,the three-dimensional porous network structure of the aerogel improves the absorption of visible light,so that more photo-generated electron-hole pairs are used in the photocatalytic reaction,and the huge specific surface area is conducive to the adsorption of dye molecules and promotes the photocatalytic degradation process.