Sen Sujat, Govindarajan Vijay, Pelliccione Christopher J, Wang Jie, Miller Dean J, Timofeeva Elena V
Energy Systems Division and ‡Electron Microscopy Center - Center for Nanoscale Materials, Argonne National Laboratory , Lemont, Illinois 60439, United States.
ACS Appl Mater Interfaces. 2015 Sep 23;7(37):20538-47. doi: 10.1021/acsami.5b05864. Epub 2015 Sep 10.
This study presents a new approach to the formulation of functional nanofluids with high solid loading and low viscosity while retaining the surface activity of nanoparticles, in particular, their electrochemical response. The proposed methodology can be applied to a variety of functional nanomaterials and enables exploration of nanofluids as a medium for industrial applications beyond heat transfer fluids, taking advantage of both liquid behavior and functionality of dispersed nanoparticles. The highest particle concentration achievable with pristine 25 nm titania (TiO2) nanoparticles in aqueous electrolytes (pH 11) is 20 wt %, which is limited by particle aggregation and high viscosity. We have developed a scalable one-step surface modification procedure for functionalizing those TiO2 nanoparticles with a monolayer coverage of propyl sulfonate groups, which provides steric and charge-based separation of particles in suspension. Stable nanofluids with TiO2 loadings up to 50 wt % and low viscosity are successfully prepared from surface-modified TiO2 nanoparticles in the same electrolytes. Viscosity and thermal conductivity of the resulting nanofluids are evaluated and compared to nanofluids prepared from pristine nanoparticles. Furthermore, it is demonstrated that the surface-modified titania nanoparticles retain more than 78% of their electrochemical response as compared to that of the pristine material. Potential applications of the proposed nanofluids include, but are not limited to, electrochemical energy storage and catalysis, including photo- and electrocatalysis.
本研究提出了一种新方法，用于制备具有高固体负载量和低粘度的功能性纳米流体，同时保留纳米颗粒的表面活性，特别是它们的电化学响应。所提出的方法可应用于多种功能性纳米材料，并能够探索纳米流体作为传热流体之外的工业应用介质，利用分散纳米颗粒的液体行为和功能。在水性电解质（pH 11）中，原始的25纳米二氧化钛（TiO₂）纳米颗粒可达到的最高颗粒浓度为20 wt%，这受到颗粒聚集和高粘度的限制。我们开发了一种可扩展的一步表面改性程序，用于用单层覆盖的丙基磺酸基团对这些TiO₂纳米颗粒进行功能化，这在悬浮液中提供了基于空间位阻和电荷的颗粒分离。在相同电解质中，由表面改性的TiO₂纳米颗粒成功制备出了TiO₂负载量高达50 wt%且粘度低的稳定纳米流体。对所得纳米流体的粘度和热导率进行了评估，并与由原始纳米颗粒制备的纳米流体进行了比较。此外，结果表明，与原始材料相比，表面改性的二氧化钛纳米颗粒保留了超过78%的电化学响应。所提出的纳米流体的潜在应用包括但不限于电化学能量存储和催化，包括光催化和电催化。
