Research On Preparation And Performance Of Graphene Oxide-based And Graphene-based Composite Materials

Graphene oxide and graphene are typical materials of the planar polycyclic aromatic hydrocarbons.Because of the honeycomb 2-D crystal structure formed by the close co-bonding of sp2 hybridized carbon atoms,they have unique electrical,optical,thermal and mechanical properties.They have become a research hotspot for new carbon-based materials at home and abroad.In this paper,the preparation of DLTA-mGO composites for the adsorption of cadmium metal ions,as well as preparation of the graphene/carbon nanotube/sodium alginate composites and its strain sensing properties were studied.In order to solve the problem that graphene oxide has poor ability to adsorb cadmium ions and cannot be separated from aqueous solution,the diethylenetriamine modified magnetic graphene oxide(DLTA-mGO)was fabricated by a catalyst-free in situ polymerization method based on DLTA,GO and Fe3O4 obtained by coprecipitation.The characteristics of the synthesized DLTA-mGO were characterized by TEM,FT-IR and XPS,and the adsorption capacity,adsorption kinetics,thermodynamics and adsorption influencing factors were studied.The results showed that:(1)The amino and imino groups were increased by DLTA modification,which greatly increased the adsorption of DLTA-mGO for Cd(II).The adsorption capacity of DLTA-mGO was 114.5 mg./g,which is 71.7% higher than that of GO and 94.7% higher than that of mGO.The magnetic saturation intensity of DLTA-mGO was 28.5 emu/g and it can be easily separated from the aqueous solution.(2)The adsorption kinetics data and the pseudo-second-order model fitting curves of DLTA-mGO had higher correlation coefficient values(R2=0.99612),indicating that the adsorption rate was mainly controlled by the chemical adsorption stage.The adsorption isotherm of DLTA-mGO was more consistent with the Langmuir adsorption isotherm(R2=0.9922),indicating that the adsorption process was mainly chemisorption by monolayers.(3)Response surface methodology(RSM)study found that there was a strong interaction between metal ion concentration(A),solution pH(B),and temperature(C),and the impact was ranked as AB>BC>AC.In view of performance improvement of low elasticity,poor mechanical stability and poor sensitivity to compression in some strain sensor materials,graphene/carbon nanotubes/sodium alginate(rGO/SA/CNTs)composite aerogels with superelasticity,excellent mechanical stability and high sensitivity based on reduced graphene oxide(rGO),carbon nanotubes(CNTs)and sodium alginate(SA)were fabricated through freeze drying and chemical reduction.The composite aerogels were characterized by SEM,TEM and FT-IR,and their hydrophobic properties,mechanical properties and electrical properties were studied.The results show that:(1)rGO/SA/CNTs-3 that has uniform pore structure and regular lamellar stacking obtained by the mass ratio of GO:SA:CNTs = 20:3:7 was good and had good fatigue strength,repeatability,mechanical stability and sensitivity.Its contact angle was 127° and it had good hydrophobicity.(2)Compared with pure GO aerogels,rGO/SA/CNTs-3 composite aerogel had high elasticity.When the strain(?)was 50%,the stress increases from 3000 Pa to 8400 Pa.The results of 200 compression rebound tests showed that the rGO/SA/CNTs-3 composite aerogel had good flexibility and stability,which was attributed to the synergy between graphene and carbon nanotubes and sodium alginate.Scanning electron microscopy analysis revealed that CNTs were embedded in GO and formed a large number of small "funnel" homogeneous pore structures.Infrared analysis showed hydrogen bonding between SA and GO.(3)The results of 500 compressive response tests showed that the relationship between the resistance response(?R/R0)and the strain ?(?=50%)of the rGO/SA/CNTs-3 composite aerogel was roughly periodic linear relationship.After 500 compression cycles,the ?R/R0 value slightly decreased from 58.0% to 55.8%.(4)When the strain was 30%,50%,70%,all of the sensitivity coefficients of rGO/SA/CNTs-3 composite aerogel were pretty good.When the strain enthalpy is 30%,the sensitivity coefficient was the highest,reaching 1.4.