title: Enhanced energy harvesting by concentration gradient-driven ion transport in SBA-15 mesoporous silica thin films.
abstract: Nanofluidic energy harvesting systems have attracted interest in the field of battery application, particularly for miniaturized electrical devices, because they possess excellent energy conversion capability for their size. In this study, a mesoporous silica (MPS)-based nanofluidic energy harvesting system was fabricated and selective ion transport in mesopores as a function of the salt gradient was investigated. Aqueous solutions with three different kinds of monovalent electrolytes-KCl, NaCl, and LiCl-with different diffusion coefficients (D+) were considered. The highest power density was 3.90 W m-2for KCl, followed by 2.39 W m-2for NaCl and 1.29 W m-2for LiCl. Furthermore, the dependency of power density on the type of cation employed indicates that the harvested energy increases as the cation mobility increases, particularly at high concentrations. This cation-specific dependency suggests that the maximum power density increases by increasing the diffusion coefficient ratio of cations to anions, making this ratio a critical parameter in enhancing the performance of nanofluidic energy harvesting systems with extremely small pores ranging from 2 to 3 nm.
authors.affiliation: Department of Mechanical Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. hwang@thml.t.u-tokyo.ac.jp and CREST, Japan Science and Technology Agency (JST), 7 Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan.
authors.forename: Junho
authors.initials: J
authors.lastname: Hwang
authors.affiliation: CREST, Japan Science and Technology Agency (JST), 7 Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan and National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Kataoka
authors.affiliation: CREST, Japan Science and Technology Agency (JST), 7 Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan and National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Endo
authors.affiliation: Department of Mechanical Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. hwang@thml.t.u-tokyo.ac.jp and CREST, Japan Science and Technology Agency (JST), 7 Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Daiguji