【作者】 孙洋；

【导师】 赵宗彬；

【作者基本信息】 大连理工大学 ， 物理化学， 2022， 博士

【摘要】 界面太阳能水蒸发（Interfacial Solar Vapor Generation,ISVG）作为新一代海水淡化和废水处理技术,具有光热转换效率高、水蒸发速率快,操作简便、成本低廉、环境友好等优点,应用前景广阔。碳基材料因其优异的宽光谱吸收性能、高效的光热传导性、稳定的物理化学性质以及良好的可扩展性等特点,成为ISVG实际应用体系中一类十分有竞争力的备选光热转换材料。针对目前碳基ISVG系统存在热传导损失大、蒸发表面易于盐沉积、低光照强度下水蒸发速率低以及功能单一等系列亟待解决的问题,本论文工作基于材料表面形貌修饰提高入射光吸收率、环境能量输入强化水蒸发速率、聚光效应提高光热转化性能和单向流动效应实现积盐消除等策略,设计构筑了系列碳基ISVG系统,优化了界面处太阳能转换、能量传输、质量传输和蒸汽扩散,实现了太阳光驱动下高效和稳定的海水淡化、废水处理及绿色电能的转化和收集。本文的主要研究内容如下:（1）基于碱土金属离子插层的氧化石墨烯纳米带薄膜材料构筑界面太阳能水-电联产系统。以氧化石墨烯纳米带为基底材料,利用碱土金属离子与含氧官能团发生的开环和配位反应,制备出一种碱土金属离子插层的氧化石墨烯纳米带自支撑薄膜光热转换材料,将其与热电模块结合,构建了一种多功能ISVG系统。基于碱土金属离子与氧化石墨烯纳米带的开环和配位作用,调控了该薄膜材料的表面形貌和结构组成,优化了蒸发界面处的太阳能转换,从而提高了该光热转换材料的宽光谱吸收性能和机械性能,使得该水电联产系统展现出高效的光热转换性能、良好的热电性能和长时效循环稳定性。在100 m W cm^-2的光强照射下,基于钡离子插层的氧化石墨烯纳米带薄膜ISVG系统可获得91.5%的光热转换效率和0.11 W m^-2的电能输出功率密度。由系统组装而成的原型装置在21天的连续室外自然光实验中,性能稳定,最高淡水收集速率和最高的输出电压可分别达到7.0 kg m^-2 day^-1和0.47 V。（2）基于生物质碳材料构筑环境能量强化的界面太阳能水蒸发系统。以廉价易得的生物质废弃物玉米芯为原料,通过低温碳化制备得到一种具有天然三维结构的光热转化碳材料。玉米芯衍生碳内部发达的互联互通分级微纳米孔隙结构为水的输运提供丰富通道的同时,改变了水分子的蒸发状态,降低了水的蒸发焓,从而提高了系统的水蒸发速率;另外,玉米芯衍生碳整体材料侧面独特的孔隙结构使其具有利用环境能量增强蒸发过程的能力,实现了环境能量对蒸发系统的净能量输入增益。通过对碳化温度、裸漏高度等实验条件进行优化,实现了对系统能量传递和气体扩散的最优设计,使得玉米芯衍生碳三维界面太阳能水蒸发系统在100 m W cm^-2的光强照射下获得了4.16kg m^-2 h^-1的超高水蒸发速率。同时,玉米芯衍生碳材料ISVG系统也展现出了优异的长时效循环稳定性和抗积盐性能。户外自然光下连续实验20天,由系统组装而成的原型装置实现了对真实海水的淡化处理,材料性能保持稳定,淡水收集速率最高可达12.32kg m^-2 day^-1。（3）基于聚光效应和流动效应实现高效界面太阳能水蒸发和电能转化。以铝箔为聚光板,热还原后的石墨烯纳米带为光热转换材料,利用琼脂糖凝胶的溶胶凝胶可逆特性,通过热浇筑和常温干燥构筑了一种具有聚光效应和单向流动效应的ISVG系统。聚光效应通过对入射太阳能进行持续精确的自主收集,优化了蒸发界面处太阳能转换和能量传递,使得系统在100 m W cm^-2的光强照射下实现了3.45 kg m^-2 h^-1的超高水蒸发速率,在50 m W cm^-2的低光强照射下水蒸发速率仍可高达1.62 kg m^-2h^-1。系统中单向流动效应通过水流的扩散和对流作用优化了海水淡化过程中的质量传递,从而有效避免蒸发界面盐累积。同时,单向流动和复合材料的结构组成特性的有机耦合通过收集水流能量实现了可持续稳定的流动电势发电,系统在160 h内连续达到0.47 V的电压输出和0.63μW的最大输出功率。碳材料与聚光效应和单体流动效应的结合促进了系统水蒸发性能和发电性能的双重增强,从而达到能量充分利用之目的。更多还原

【Abstract】 As a new generation of desalination and wastewater treatment technology,interfacial solar vapor generation（ISVG）technology has a promising application prospect due to its high photothermal conversion efficiency,fast water evaporation rate,low cost,and environmental friendliness,etc.Meanwhile,carbon-based materials have become a kind of competitive candidate for photothermal conversion materials in ISVG application systems due to their excellent wide spectrum absorption performance,efficient photothermal conversion capability,stable physical and chemical properties,as well as good scalability.However,there exists a series of urgent problems to be solved in carbon-based ISVG systems,such as larger conductive heat loss,severe salt deposition on the evaporation surface,and low photothermal utilization efficiency at low light intensities and simplex function,etc.In the present work,a series of carbon-based ISVG systems are designed and constructed based on the strategies of material surface morphology modification for improving light absorption,the environmental energy input for enhancing water evaporation rate,solar-concentrated effect for improving photothermal conversion property,and one-way flow effect for the removal of salt deposition,which optimizes solar energy conversion,energy transfer,mass transfer and vapor diffusion at interfaces and enable efficient and stable seawater desalination,sewage treatment and green power conversion driven by solar irradiation.The main results are summarized as followings:（1）Construction of interfacial solar-driven water-electricity cogeneration system based on graphene oxide nanoribbons paper intercalated with alkaline earth metal ions.Using graphene oxide nanoribbons（GONRs）as substrate,self-supported GONRs paper with alkaline earth metal ions intercalation for photothermal conversion was prepared by the ring-opening and coordination reaction between alkaline earth metal ions and oxygen-containing functional groups.Combined with the thermoelectric module,a multi-functional ISVG system was constructed.Based on the ring-opening and coordination interactions between alkaline earth metal ions and graphene oxide nanoribbons,the surface morphology and structural composition of the thin film material are regulated to optimize the solar energy conversion at the evaporation interface,thus improving the broad-spectrum absorption performance and mechanical properties of the photothermal conversion material,which enables the cogeneration system to exhibit efficient photothermal conversion performance,good thermoelectric performance and long-time cycle stability.Under 100 m W cm^-2 intensity irradiation,the ISVG system based on GONRs paper with barium ion intercalation achieves a photothermal conversion efficiency of 91.5%and an output power density of 0.11 Wm^-2.The performance of the system is stable during 21 days of the outdoor natural light experiment.The highest fresh water collection rate and the highest output voltage can reach 7.0 kg m^-2 day^-1 and 0.47 V,respectively,during the outdoor test.（2）Construction of interfacial solar vapor generation enhanced by environmental energy input based on biomass carbon material.A photothermal carbon material with a natural three-dimensional structure was fabricated by low-temperature carbonization using natural corncob as raw material.The corncob-derived monolithic carbon possesses well-interconnected hierarchical micro/nano pore structures,which provide numerous pathways for the transportation of raw water.It is revealed that the unique structure of the corncob-based carbon enables the reduction of water evaporation enthalpy,which enhances the water evaporation rate.More importantly,the unique pore structure on the side around the monolith carbon allows the occurrence of side evaporation and the input of environmental energy.By optimizing the experimental conditions such as carbonization temperature and bare leakage height,the optimal design of energy transfer and gas diffusion of the system is achieved,as a result,the corncob-derived carbon-based interface solar water evaporation system exhibits an ultrahigh evaporation rate of 4.16 kg m^-2 h^-1 under 100 m W cm^-2 intensity irradiation.The ISVG system of corncob-derived carbon material also shows excellent long-time cyclic stability and salt deposition resistance.A demonstration experiment for real seawater desalination is carried out outdoor under natural light for 20 days,the system works steadily and achieves the highest fresh water collection rate up to 12.32 kg m^-2 day^-1.（3）Water-electricity cogeneration based on solar concentration effect and water flow effect.An ISVG system with a solar-concentrated effect and one-way water flow effect was fabricated by hot pouring and drying at room temperature based on the reversible sol-gel property of agarose gel,which was mainly consisted of aluminum foil as light-condenser and thermally-reduced graphene oxide nanoribbons as photothermal conversion material.The concentrated solar effect optimizes solar energy conversion and energy transfer at the evaporation interface through continuous and precise autonomous collection of incident solar energy,enabling the system to achieve an ultra-high water evaporation rate of 3.45 kg m^-2 h^-1 at a light intensity of 100 m W cm^-2 and up to 1.62 kg m^-2 h^-1 at a low light intensity of 50 m W cm^-2.Moreover,the one-way flow effect in the system optimizes the mass transfer during desalination through the continuous diffusion and convection of water,thus effectively avoiding salt accumulation at the evaporation interface.At the same time,the combination of unidirectional flow and the structural properties of the composite material enables sustainable and stable flow potential generation by harvesting water flow energy,and voltage output of 0.47V and maximum output power of 0.63μW are achieved during the experiment lasting for 160h.Therefore,the combination of carbon material with solar-concentrated effect and one-way water flow effect can promote the coupling enhancement of water evaporation performance and power generation performance of the system,which may provide a new pathway for making the most utilization of energy.更多还原