Preparation And Properties Of Thin Wood Based Photothermal Conversion Materials

In the face of the global scarcity of fresh water resources,how to obtain clean water resources from abundant seawater and polluted wastewater in a green,economical and efficient way has received a lot of attention from researchers.The way of generating clean water by interfacial photothermal evaporation using abundant and renewable solar clean energy has become a promising technology because of its advantages of green,energy saving,simplicity and efficiency.The preparation of photothermal conversion materials with high photothermal conversion efficiency,cheap and easy to scale up is a prerequisite.In this paper,natural,renewable,cheap and easy to obtain decorative thin wood is used,based on its special high porosity porous structure,excellent hydrophilicity,easy to modify and many other advantages.Furthermore,the wood surface was designed with in-situ polymer and white rot mycelium to enhance the light absorption,and woodbased photothermal conversion materials with excellent photothermal conversion performance were obtained.The details are as follows:(1)The basic properties and photothermal conversion performance of thin wood were investigated.Thin wood obtained from poplar(representative of broad-leaved wood species)and fir(representative of coniferous wood species)was studied.The microstructure of thin wood was analyzed by optical microscopy,and its chemical resistance and light absorption properties were also investigated,and the effects of different wood species and thin wood thickness on its photothermal performance were discussed.The results showed that the thin woods obtained from poplar and fir have welldeveloped capillary porous structures and good resistance to strong acids and alkalis,and have certain light absorption ability in the UV and some visible wavelengths from 300600 nm.The evaporation rate of 0.6 mm thickness of fir wood is 0.77 kg·m-2·h-1,and the photothermal conversion efficiency is 50.10%.(2)A thin wood-based interfacial photothermal evaporator(PEDOT/Wood)with two surface micro-nano structures was prepared by controlled growth of polythiophene nanoparticles(PEDOT)on the thin wood surface using vapor deposition-in-situ polymerization technique.The morphological structure,chemical composition and optical absorption properties of PEDOT/Wood were investigated using SEM,FTIR,XPS,and UV/Vis/NIR diffuse reflectance tests.The results show that modulating the volatilization rate of thiophene monomer can successfully synthesize PEDOT nanoparticles with two morphologies,needle-like and button-like,on the surface of thin wood,and their evaporation rates can reach 1.42 and 1.48 kg·m2·h-1 under one sunlight,respectively(88.48%and 92.36%of photothermal conversion efficiency,respectively).Simulated finite element simulations further confirm that its nanostructure facilitates the improvement of the photothermal conversion performance.In addition,this interfacial evaporator also shows excellent performance in desalination and wastewater treatment containing organic dyes/heavy metal ions for removal.(3)A new thin wood-based interfacial photothermal evaporator was designed by using natural white-rot mycelium,which is susceptible to wood infection,to structurally modify the thin wood surface,immobilizing the mycelium with the help of polydopamine adhesion function and as a light-absorbing coating.The structure and properties of thin wood were analyzed by SEM,FTIR,thermal conductivity test,UV/Vis/NIR diffuse reflection test and other characterizations,and the effect of dopamine polymerization conditions on the photothermal conversion performance was investigated.The results showed that the introduction of mycelial microstructure was beneficial to the photothermal conversion performance of thin wood,while its photothermal evaporation rate increased significantly to 1.61 kg·m-2·h-1 under one sunlight when the dopamine concentration was 5 g·L-1 and the polymerization temperature was 50℃,and the photothermal conversion efficiency was as high as 97.50%.Meanwhile,the desalination and wastewater treatment performance tests showed that the new thin wood-based interfacial photothermal evaporator has excellent desalination and wastewater purification capabilities.