Liquid-solid contact electrification is a useful mechanism to harvest wasted micromechanical energy. In this study, we investigate how the surface properties of a solid substrate affect contact electrification efficiency. Substrate surfaces were modified from hydrophilic to hydrophobic by changing the density of self-assembled monolayers (SAMs) on a SiO2 surface. A substrate with a partially-covered SAM exhibited superior performance. The partially-covered SAM substrate is hydrophobic enough to induce quick dewetting of water from the surface and sufficiently electronegative to induce a high charge density on the surface. The quick dewetting results from the aliphatic tail groups of the SAM and -OH groups make the SiO2 surface electronegative; these two competing properties can be simultaneously obtained by optimizing the SAM density. Our findings contribute to the understanding of contact electrification in liquid-solid-type energy-harvesting devices and advance the strategies to maximize the electrification efficiency by optimizing surface geometries and properties.Liquid-solid contact electrification is a useful mechanism to harvest wasted micromechanical energy. In this study, we investigate how the surface properties of a solid substrate affect contact electrification efficiency. Substrate surfaces were modified from hydrophilic to hydrophobic by changing the density of self-assembled monolayers (SAMs) on a SiO2 surface. A substrate with a partially-covered SAM exhibited superior performance. The partially-covered SAM substrate is hydrophobic enough to induce quick dewetting of water from the surface and sufficiently electronegative to induce a high charge density on the surface. The quick dewetting results from the aliphatic tail groups of the SAM and -OH groups make the SiO2 surface electronegative; these two competing properties can be simultaneously obtained by optimizing the SAM density. Our findings contribute to the understanding of contact electrification in liquid-solid-type energy-harvesting devices and advance the strategies to maximize the electrifica...

中文翻译：

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接触带电效率对水-固界面表面能的依赖

液固接触带电是收集浪费的微机械能的有用机制。在这项研究中，我们研究了固体基材的表面特性如何影响接触带电效率。通过改变 SiO2 表面上自组装单分子层 (SAM) 的密度，将基材表面从亲水性改性为疏水性。具有部分覆盖的 SAM 的基板表现出优异的性能。部分覆盖的 SAM 基材具有足够的疏水性，可以使水从表面快速去湿，并且具有足够的负电性，可以在表面上产生高电荷密度。SAM 和 -OH 基团的脂肪族尾部基团导致快速去湿，使 SiO2 表面带电；这两个相互竞争的特性可以通过优化 SAM 密度同时获得。我们的研究结果有助于理解液固型能量收集装置中的接触带电，并通过优化表面几何形状和特性推进使带电效率最大化的策略。液-固接触带电是收集浪费的微机械能的有用机制。在这项研究中，我们研究了固体基材的表面特性如何影响接触带电效率。通过改变 SiO2 表面上自组装单分子层 (SAM) 的密度，将基材表面从亲水性改性为疏水性。具有部分覆盖的 SAM 的基板表现出优异的性能。部分覆盖的 SAM 基材具有足够的疏水性，可以使水从表面快速去湿，并且具有足够的负电性，可以在表面上产生高电荷密度。SAM 和 -OH 基团的脂肪族尾部基团导致快速去湿，使 SiO2 表面带电；这两个相互竞争的特性可以通过优化 SAM 密度同时获得。我们的研究结果有助于理解液固型能量收集装置中的接触带电，并推进使电气化最大化的策略……