Design And Application Of Porous Carbon-Based Photothermal Utilization System

With the development of The Times,water resource shortage,environmental pollution and energy shortage have become important challenges facing human society.The key to solve these problems is to explore and use appropriate green and sustainable ways.Solar energy is a kind of inexhaustible and renewable energy.Using solar photothermal conversion technology to realize water evaporation,water purification and hydrogen energy production has become one of the ideal solutions to solve these challenges.Solar photothermal conversion technology is a process that uses photothermal materials to absorb solar energy and convert it into heat energy to achieve different applications and improve the efficiency of energy conversion.However,at present,the reasonable application of photothermal conversion technology is limited by the problems such as weak absorption capacity of photothermal materials,high heat loss of photothermal system and insufficient utilization of photothermal effect.Therefore,further exploration and breakthrough are needed to realize efficient conversion and utilization of solar energy.In this paper,porous carbon and its composite structure are selected as the material system,and photothermal water evaporation,photothermal co-adsorption of pollutants and photothermal catalysis of aquatic hydrogen are targeted for application.By adjusting the morphology and structure of porous carbon,design of photothermal evaporator,utilization of conductive heat loss and construction of three-way catalyst,the absorption of photothermal materials and water evaporation rate and efficiency of the photothermal system are improved.Expand the capacity of photothermal co-adsorption of pollutants and photothermal catalytic hydrogen production,and finally realize the efficient conversion application of solar energy.Specific research contents are as follows:（1）Firstly,three-dimensional Porous carbon nanomaterials,porous carbon nanomaterials,were obtained by chemical vapor deposition（CVD）method with Na Cl as the template and glucose as the carbon source.PCN).Then activated porous carbon（activated PCN）was prepared at different KOH adding ratios（PCN:KOH=1:1,1:2,1:3,1:4）and high temperature.It was found that compared with unactivated PCN,using PCN:The sample activated with the ratio of KOH=1:4 has a hierarchical porous structure consisting of micron-scale pores,mesoporous pores and micropores,which not only gives it good full spectrum absorption capacity,high specific surface area(1867.71 m²·g^-1)and pore volume(1.04 cm³·g^-1),but also enhances water activation and reduces enthalpy of evaporation through pores.Finally,the solar driven interfacial water evaporation system achieves the evaporation rate of 1.42 kg·m^-2h^-1and the photothermal conversion efficiency of 66.3%,and shows excellent stability and salt tolerance.In addition,through monitoring the temperature of evaporating water under the photothermal system,it is found that after 60 min,the water below can maintain～31℃,～36℃and～38℃under 1 kw·m^-2,2 kw·m^-2and 3 kw·m^-2.This indicates that during the evaporation of solar water,a considerable amount of heat is transferred to the water below,resulting in conductive heat loss.With the decrease of water mass,the conduction heat loss decreases and the photothermal water evaporation performance increases gradually.It is worth mentioning that when the water mass is 10 g,the water evaporation rate and steam generation efficiency reach 1.78 kg·m^-2·h^-1and 83.2%,respectively.（2）Using the conduction heat loss generated by solar photothermal water evaporation system,the photothermal co-adsorption ability of activated PCN at different water temperatures was studied.The results showed that the removal of 50 mg L^-1Rhodamine B（Rh B）,methylene blue（MB）and methyl orange（MO）was achieved faster by 3 mg activated PCN sample（KOH:PCN=1:4）at 304 K compared with 298 K.In addition,the maximum adsorption capacity of Rh B reached 1610 mg g^-1at 309 K conduction temperature,which was12%higher than that of activated sample at 298 K room temperature.This fully indicates that the conductive heat generated by the water evaporation system can promote the photothermal co-adsorption capacity of activated PCN samples for organic pollutants.In addition,the adsorption-desorption cycle experiment confirmed that the activated PCN sample has good stability and recycling ability.（3）In this paper,photothermal material PCN and stripped Mo S₂were added into Zn In₂S₄reaction system,and three-way PCN@Mo S₂/Zn In₂S₄composite catalyst was prepared by one-step hydrothermal method.It is a combination of Mo S₂/Zn In₂S₄nanoflower-coated PCN that effectively integrate photogeneration carrier management and the photothermal conversion effect of PCN to facilitate the production and transfer of hot electrons,ultimately improving the efficiency of light-driven photothermal cracking of hydrogen in water.The results show that under the condition of controlling reaction temperature（6℃）,PCN11@Mo S₂/Zn In₂S₄can reach 14.11 mmol·g^-1·h^-1hydrogen evolution rate,3.2 times of Mo S₂/ZIS,64 times of pure ZIS.After the cooling water circulation is closed,the heat generated by the photothermal conversion of PCN further promotes the catalytic activity.The hydrogen evolution activity of PCN11@Mo S₂/Zn In₂S₄is up to 18.48 mmol·g^-1·h^-1,which fully indicates that the introduction of PCN improves the full spectrum absorption of the photothermal catalyst.A large amount of heat is generated in a photothermal catalytic system to promote hydrogen evolution activity.