Preparation Of Graphene Composites For The Application Of Photothermal Water Evaporation

With the shortage of fresh water resources in the world,the problem of water pollution has become increasingly prominent,and the technology of clean water production has been developed rapidly.Solar-driven water evaporation is considered as one of the green,effective and sustainable application technologies.It received a lot of attention.At present,there are more and more researches on solar driven water evaporation technology,and relevant reports emerge endlessly,but there are still some problems.It mainly includes:high cost,low evaporation efficiency,complex process and not suitable for complex environment.Therefore,it is necessary to design solar evaporators with excellent photothermal performance and multifunctional applications through simple processes.In this paper,one-step synthesis of graphene and metal compound composites by laser thermal method.And the photothermal properties and applications of composite materials were studied.The main conclusions obtained are as follows:(1)Graphene oxide quantum dots(GOQDs)were synthesized as a photothermal agent by hydrothermal method using coffee grounds as the carbon source.GOQDs are uniformly dispersed in aqueous solutions of ammonia and zinc acetate.Preparation of GOQDs/Zn O nano complexes by laser thermal method.The experimental results showed that the solution temperature can be regulated by adjusting the content of GOQDs in the solution,and nanocomplexes with different GOQDs/Zn O content ratios can be synthesized.Photothermal driven water evaporation experiments showed that the best photothermal performance of GOQDs/Zn O complexes obtained with 40 mg GOQDs addition.A water evaporation rate of3.16 kg·m^-2·h^-1 can be obtained using this complex under two simulated sunlight.And the composite showed excellent antibacterial effect against both E.coli and Staphylococcus aureus.(2)By the laser thermal method,reduced graphene oxide/copper sulfide(r GO/Cu S)nanocomplexes were produced in aqueous Na OH solutions containing graphene oxide(GO),Cu Cl₂ and CH₄N₂S.In the laser thermal preparation process,with the enhancement of laser power,the content of copper sulfide in the hexagonal crystal system in the sample gradually increased,and graphene oxide was reduced.Experimental results of photothermal driven water evaporation using pure water show:best photothermal effect of nano complexes prepared at 8 W laser intensity,and the photothermal driven water evaporation rate can reach2.09 kg·m^-2·h^-1.Results of photothermal driven water evaporation tests using contaminated water show:nanocomplexes prepared at 8W laser intensity have significant purification effect on unevaporated bulk phase water.In a simulated sunlight,after 1h of light,The removal of rhodamine B(Rh B)in bulk phase water reached 25.5%,m-dinitrobenzene(m-NB)35.8%and nickel ion(Ni²⁺)25.6%.Further outdoor experiments were conducted on the contaminated water,and the levels of Rh B,m-NB and Ni²⁺in the collected distilled water were significantly reduced after 12 h of natural evaporation outdoors.