Limited Electron-Dominated Electrorheological Response with TiO<sub>2</sub> Buffer Layer.

Chen, Sai; Kuznetsov, Nikita M; Hou, Longtao; Choi, Hyoung Jin; Zhang, Ke; Zhao, Jiupeng; Li, Yao · Nano Lett · 2025

basic_science · Level V

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Abstract

We report porous carbon sphere electrorheological (ER) nanoparticles coated with a titanium dioxide layer (HCs@TiO<sub>2</sub>). Utilizing the buffering effect of amorphous TiO<sub>2</sub>, the HCs@TiO<sub>2</sub> ER fluid (ERF) shows a yield stress that exceeds that of previous carbon-based ER nanomaterials. The mechanisms of the high ER response are elucidated through the analysis of the dielectric properties, demonstrating that the amorphous TiO<sub>2</sub> shell not only restricts the electron-dominated motion but also significantly improves the interfacial polarization. Furthermore, the HCs@TiO<sub>2</sub> ERF exhibits superior sedimentation stability and low current density, which is attributed to the formation of a hydrogen bond network. The rheological behavior of HCs@TiO<sub>2</sub> ERF is analyzed using the Bingham and Cho-Choi-Jhon model, where the dynamic yield stress as a function of electric field strength is fitted using a generalized yield stress equation. These analyses indicate that local electrostatic accumulation between the hybrid shells benefits the ER response.