Green cellulose- based solar light capturing composite films made of carbon nanotubes (CNT) and cellulose nanofibrils (CNF), with high photothermal conversion performance, were designed and developed. Thanks to the strong electrostatic interactions between carboxyl- rich CNFs (obtained from 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO) mediated oxidation), and cationic-modified CNTs using cetyltrimethylammonium bromide, the resultant CNT/CNF composite (FTC) films are uniform and exhibit excellent mechanical properties. More importantly, the effect of CNT/CNF ratio in the FTC films on their photothermal conversion capacity and coefficient of thermal expansion (CTE) was investigated. The FTC film with 50 % CNT incorporation shows both high photothermal conversion capacity and high negative CTE, and its application for solar energy harvesting was explored, including seawater desalination, photothermal power generation and light- driven actuators. The FTC film exhibits high light-induced desalination capability, with water evaporation rate reaching 1.23 Kg m^-2 h^-1 at an irradiance of 1 kW m^-2 (evaporation efficiency of 84.5 %) and ion concentrations in purified water decreasing by 4 orders of magnitude. The FTC film can also be assembled into photothermal power system, achieving an output voltage of 310 mV at an irradiance of 3 kW m^-2. With the assistance of a boost module, it can be used to re-charge a cell phone. A light-driven FTC/polytetrafluoroethylene (PTFE) double- layered actuator was also designed. Benefiting from the negative CTE of the FTC film, the actuator has a high sensitivity and achieves a bending curvature of 3.3 cm^-1 at an irradiance of 0.74 kW m^-2. This study presents a scalable, yet simple strategy to design green/sustainable cellulose- based solar energy harvesting devices that can have multiple applications.

设计开发了由碳纳米管（CNT）和纤维素纳米原纤维（CNF）制成的具有高光热转换性能的绿色纤维素基太阳光捕获复合膜。由于富含羧基的 CNF（从 2, 2, 6, 6-四甲基哌啶-1-氧基 (TEMPO) 介导的氧化获得）和使用十六烷基三甲基溴化铵的阳离子改性 CNT 之间的强静电相互作用，所得 CNT/CNF 复合材料（ FTC) 薄膜均匀并表现出优异的机械性能。更重要的是，研究了 FTC 薄膜中 CNT/CNF 比率对其光热转换能力和热膨胀系数 (CTE) 的影响。掺入 50% CNT 的 FTC 薄膜显示出高光热转换能力和高负 CTE，并探索了其在太阳能收集方面的应用，包括海水淡化、光热发电和光驱动执行器。FTC薄膜表现出高光诱导脱盐能力，水分蒸发率达到1.23 Kg m^-2 h ^{- 1在 1 kW m - 2}的辐照度下（蒸发效率为 84.5 %），纯化水中的离子浓度降低了 4 个数量级。^{FTC薄膜还可以组装成光热发电系统，在3 kW m - 2}的辐照度下实现310 mV的输出电压。在升压模块的帮助下，它可以用来给手机充电。还设计了光驱动的 FTC/聚四氟乙烯 (PTFE) 双层致动器。^{得益于FTC薄膜的负CTE，致动器具有高灵敏度，在0.74 kW m - 2}的辐照度下实现了3.3 cm ^{- 1}的弯曲曲率. 本研究提出了一种可扩展但简单的策略来设计可具有多种应用的绿色/可持续的基于纤维素的太阳能收集设备。