Design And Application On Solar Water Evaporation System Of Fiber-loaded Carbon Dots And CuS Hybrid Gel

With the increasing population on earth,water shortage has become one of the major threats facing human society.In recent decades,great efforts have been made to develop effective and reliable solutions to the problem of water shortage,but the existing water supply technologies in practical application are not conducive to sustainable development at the cost of deteriorating the energy environment.Therefore,solar driven interface water evaporation as a low-cost,sustainable development technology has become the focus of attention,using sunlight as energy power,seawater as a resource to generate water steam is considered to be the most promising solution to the shortage of fresh water resources.But due to the evaporation efficiency is not high,evaporator instability problems urgently needed to solve in practical application,so in this article,we design a new type of composite thermal material,with rich source,good biocompatibility and low cost green carbon dots(CDs)and semiconductor copper sulfide(Cu S)in situ composite,the load on the polyacrylonitrile(CPFs)carbide substrate,Finally,it was coated with polyvinyl alcohol(PVA)gel and designed as a composite solar driven interface water evaporation system.The system is stable and resistant to harsh environment,but still shows high evaporation effect and conversion efficiency.The main work is as follows:(1)Design a set of stable and efficient solar interface water evaporation system.Commercial polyacrylonitrile fibers were calcined into carbonized polyacrylonitrile fibers(CPFs)at 500?.During the preparation of Cu S,CDs and CPFs were added into thiourea solution and reacted together.By hydrothermal preparation,CDs@Cu S complex could be uniformly arranged on the fibers.The stable solar evaporator CDs@Cu S-loading CPFs hybrid gel with certain structural strength is formed.It can be seen from the characterization results of SEM,TEM and HETEM that CDs and Cu S are closely bonded in microstructure,and are evenly arranged on the fiber surface and completely wrapped by PVA,forming a stable structure.By regulating the amount of CDs introduced,the concentration of precursor and the reaction time of Cu S,the structural morphology of Cu S was changed accordingly,so as to improve the absorption rate and photothermal conversion efficiency.Finally,the solar driven interface water evaporation system reached 2.66 kg m^-2 h^-1 evaporation rate and 95.9%photothermal conversion efficiency.Compared with Cu S,the evaporation rate and conversion efficiency of the simple sample evaporator are significantly improved,and it shows good stability in the cycle experiment and strong acid and alkali resistance environment.(2)A novel proof-of-concept strategy is proposed to integrate a photothermal converter with photovoltaic power to achieve efficient seawater desalination.It was found that photosensitive electrons of CDs and Cu S nanocomposites can be pumped out to make full use of the energy captured from sunlight under the appropriate voltage.This allows steam generation in 3.5 wt%brine at a rate of more than 6.66 kg m^-2 h^-1 under one sun,with a solar-steam efficiency of up to 218%.Such high performance is attributed to the instantaneous release of more heat energy in the confined photothermal layer,which causes more water trapped in the layer to vaporize.In addition,the experimental results show that the solar evaporation performance of the system is determined by the voltage applied by the solar collector and the interfacial charge transfer efficiency under constant solar illumination.