碳基光热膜的功能化分层设计及促进水蒸发性能研究

Fast solar driven water evaporation with photothermal materials opens a novel pathway for high-efficiency water separation in the fields of desalination and wastewater treatment, exhibiting particularly economic, technological and environmental interest. However, to date, the key precondition for a viable practical application of this process is the significant improvement of evaporation efficiency in the photothermal enhanced water evaporation process with the systematic understanding of the critical influencing factors on photothermal evaporation. In this proposal, a functionally layered design will be developed on carbon based photothermal membrane to hasten water evaporation by the optimization of photo-thermal conversion efficiency and water transfer rate. The upper water-spreading layer, composited by reduced graphene oxide and carbon nanoparticles, will shift the structural stability and photo-thermal conversion efficiency of membrane. With the hydrophilic GO/GQD doping, the micro-scaled water channels will be built by the inside the water-diversion layer to realize the adjustment of water transfer rate. Additionally, via the combination of functional layers, the equilibrium relationship and the effect to photothermal evaporation will be revealed between photo-thermal conversion efficiency and water transfer rate by synthetical adjustment. And the carbon membrane with outstanding performance on photothermal evaporation will be developed. The development of this project can not only provide important theoretical basis and experience on the rational design of efficient photothermal evaporation membrane, but be beneficial for the research on the fundamental including energy conversion and mass transfer in the photothermal evaporation system.

利用光热材料实现太阳光驱动高效水蒸发在海水淡化和污水处理等领域具有重要的研究意义。系统综合地研究光热水蒸发过程的关键影响因素，实现水蒸发效率的提升是目前亟待解决的关键问题。本项目拟对碳基光热膜进行功能化分层设计，优化光热转化效率和水传输速率，提高光热膜的水蒸发效率。通过调变光热膜铺展层中石墨烯和纳米碳颗粒的含量，考察膜结构稳定性及光热转化性能。此外，在光热膜的导水层中引入亲水性的GO/GQD，构筑微观水通道，调控水传输速率。通过改变铺展层和导水层实现对光热膜微结构的调控，协同光热转化和水传输过程，揭示水蒸发效率与光热转化效率和水传输能力的内在联系，进而开发出具有优异水蒸发性能的碳基光热膜。本项目的顺利开展一方面为高性能光热蒸发膜材料的开发提供重要理论依据，另一方面为光热蒸发体系内能量过程与传质过程等重要基础性问题的深入研究奠定基础。

开发高性能光热材料实现太阳光驱动高效水蒸发在海水淡化和污水处理等领域具有重要的研究意义。针对光热材料的主要研究方向集中在通过组成及结构的调控，综合提高光吸收效率，降低热传递损失，同时优化水传输，实现高效水蒸发的目的。为探究光热水蒸发过程中的关键影响因素，提高水蒸发效率，本项目发展了纳米形貌复合的策略，开发了复合碳基光热膜，通过对其组成调控光热膜微结构，协同优化光吸收与水传输。以氧化石墨烯及碳纳米管组成的复合碳基光热膜的光热转化效率相比于单一组分光热膜提高超过35%。针对提出的分层设计中导水层隔热效果较低的问题，发展了以基苯乙烯泡沫为隔热层的分层设计，大大减少热量向水体中的传导损失。综合上述研究，为进一步突破蒸发效率极限，开发具有三维仿生形貌的光热锥，利用其空腔限域空间实现99.2%的太阳光吸收。通过组成的优化调控光热锥的表面浸润性，保证高的水传输性能，同时借助高效的热辐射回收及热传导控制，使光热转化效率达93.8%，是同材质平面膜效率的1.7倍。本项目创新性地利用不同组分纳米形貌差异调控复合膜材料微结构，实现对能量利用与物质传输过程的综合调控，揭示了光热蒸发效率受光吸收、热传递与水传输三个关键因素的综合影响，并发现光热材料微结构及宏观形貌是调变关键因素的重要手段。本项目的研究不仅按照要求完满完成基金项目，同时进一步推进了光热蒸发体系的前沿研究。对光热蒸发过程中传质传热基础问题的研究成果为高性能光热膜材料的开发提供重要理论依据，有助于领域的发展。