Gan Wentao, Wang Yaoxing, Xiao Shaoliang, Gao Runan, Shang Ying, Xie Yanjun, Liu Jiuqing, Li Jian
Key Laboratory of Bio-based Material Science & Technology, Northeast Forestry University, Ministry of Education, Harbin 150010, China.
Engineering Research Center of Advanced Wooden Materials, Ministry of Education, Harbin 150010, China.
ACS Appl Mater Interfaces. 2021 Feb 17;13(6):7756-7765. doi: 10.1021/acsami.0c21384. Epub 2021 Feb 3.
The architecture of cellulose nanomaterials is definitized by random deposition and cannot change in response to shifting application requirements. Herein, we present a magnetic field-controlled cellulose film derived from wood that exhibits great magnetic properties and reliable tunability enabled by incorporated FeO nanoparticles and cellulose nanofibers (CNF) with a large length-diameter ratio. FeO nanoparticles are dispersed in suspensions of CNF so as to enhance the magnetic response. The plane magnetic CNF can be processed to form a three-dimensional (3D) flower-like structure along the magnetic induction line after applying an external magnet. Inspired by the fluidic transport in natural flowers, a bilayer structure was created using the 3D flower-like film as the solar energy receiver and natural wood as the water pathway in a solar-derived evaporation system. Compared with a planar cellulose film decorated with FeO, the 3D structure design can greatly improve the evaporation rate from 1.19 to 1.39 kg m h and the efficiency from 76.9 to 90.6% under 1 sun. Finite element molding further reveals that the 3D structural top layer is beneficial for the formation of a gradient temperature profile and the improvement of the energy efficiency through the reduction of thermal radiation. The magnetically controlled fabrication represents a promising strategy for designing cellulose nanomaterials with a complicated structure and controllable topography, which has a wide spectrum of applications in energy storage devices and water treatment.
纤维素纳米材料的结构由随机沉积确定，无法根据不断变化的应用需求而改变。在此，我们展示了一种由木材衍生的磁场控制纤维素薄膜，它具有优异的磁性和可靠的可调性，这得益于掺入的具有大长径比的FeO纳米颗粒和纤维素纳米纤维（CNF）。FeO纳米颗粒分散在CNF悬浮液中以增强磁响应。施加外部磁场后，平面磁性CNF可沿磁感应线加工形成三维（3D）花状结构。受天然花朵中流体传输的启发，在太阳能驱动的蒸发系统中，使用3D花状薄膜作为太阳能接收器，天然木材作为水通道，创建了一种双层结构。与用FeO装饰的平面纤维素薄膜相比，3D结构设计可在1个太阳光照下将蒸发速率从1.19 kg m² h大幅提高到1.39 kg m² h，效率从76.9%提高到90.6%。有限元建模进一步表明，3D结构顶层有利于形成梯度温度分布，并通过减少热辐射提高能量效率。这种磁场控制制造代表了一种设计具有复杂结构和可控形貌的纤维素纳米材料的有前景的策略，在能量存储装置和水处理方面有广泛的应用。
