Photothermal effect on Fe3O4 nanoparticles irradiated by white-light for energy-efficient window applications
Photothermal effect on Fe3O4 nanoparticles irradiated by white-light for energy-efficient window applications
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DOI：
10.1016/j.solmat.2016.11.039
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发表时间：
2017-03
影响因子：
6.9
通讯作者：
Yuan Zhao;M. Sadat;A. Dunn;Hong Xu;Chien-Hung Chen;W. Nakasuga;R. Ewing;D. Shi
中科院分区：
文献类型：
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作者：
Yuan Zhao;M. Sadat;A. Dunn;Hong Xu;Chien-Hung Chen;W. Nakasuga;R. Ewing;D. Shi
一个显着的能量损失的结果，从不良的隔热的商业和公共建筑。窗户将大部分建筑物的加热和冷却能量扩散到外部环境中，代表美国一次能源的4.1四分之一英热单位的年度影响。目前的高效窗户技术依赖于双层隔热玻璃单元，其间具有隔热气体。一个关键的挑战是在不依赖隔热材料的情况下降低窗户的导热性。光热效应可以用于可以收集太阳能以减少热损失的特定功能。隔热效率通过U系数来量化，U系数定义为通过窗格的每单位面积的热通量（H）与窗户内表面和外部温度之间的差值（ΔT）的比率。在太阳照射下，单窗格可以“自热”，这是纳米颗粒涂层的光热效应。这可以有效地降低Δ T，以增强隔热。在这项研究中，光热效应对Fe 3 O 4纳米粒子的太阳光刺激的纳米粒子在溶液中，并作为节能窗的薄膜进行了研究。的Fe 3 O 4纳米粒子的表面功能化与不同的聚合物，以调节胶体稳定性和调查的光热效应。在白光照射下，不同表面涂层的Fe 3 O 4在水悬浮液和薄膜中的光热加热效率均远高于近红外（NIR）。根据Fe 3 O 4的能带结构确定了其光热效应的机制。根据不同Fe 3 O 4纳米颗粒的吸收光谱，得到了Urbach能级和带隙。Urbach“尾巴”被发现与纳米颗粒表面缺陷结构一致，而带隙（~3.1 eV）对应于Fe 3 O 4八面体位置的电子跃迁。我们还讨论了基于吸收的光子物理负责大大增强光热加热的白光相比，近红外。基于光热加热，获得了纳米颗粒涂层的U因子，这些纳米颗粒涂层在生产节能窗户方面显示出希望。
A significant energy loss results from the poor thermal insulations of the commercial and public buildings. Windows diffuse a large fraction of building heating and cooling energy to the external environment, representing an annual impact of 4.1 quadrillion British thermal unit of primary energy in the US. The current technology for efficient windows relies upon the double-pane insulated glass unit with an insulating gas in between. A key challenge is to reduce thermal conductivity of the windows without relying on insulating materials. The photothermal effect can be possibly utilized for particular functionalities that can collect solar energy for reducing heat loss. The insulation efficiency is quantified through the U-factor, defined as the ratio of the heat flux (H)per unit area through the pane to the difference (ΔT)between the window interior surface and exterior temperatures. Upon solar irradiation, single-panes can “self-heat”viathe photothermal effect from the nanoparticle coatings. This can effectively reduce ΔTfor enhanced thermal insulation. In this study, the photothermal effect on Fe3O4nanoparticles stimulated by solar light was investigated for nanoparticles in solutions and as thin films for energy–efficient windows. The Fe3O4nanoparticles were surface-functionalized with different polymers to modulate colloidal stability and for the investigation of the photothermal effect. The photothermal heating efficiencies of Fe3O4with different surface coatings were found to be much greater under the white-light irradiation than near infrared (NIR) in both aqueous suspension and as thin films. The mechanism for the photothermal effect of Fe3O4was identified in terms of its band structure. Both Urbach energy and band gap were obtained based on absorption spectra of various Fe3O4nanoparticles. The Urbach “tail” was found consistent with nanoparticle surface defect structures, while the band gap (~3.1 eV) corresponded to the electronic transitions in the octahedral site of Fe3O4. We also discuss the absorption-based photonic physics responsible for the much-enhanced photothermal heating by white-light as compared with NIR. Based on the photothermal heating, the U-factors were obtained with the nanoparticle coatings that show promise in producing energy efficient windows.