“…5a ). Previous studies have presented that ions on solid surfaces typically originate from various sources 42 , mainly including ionization reaction on chemically active solid surfaces 20 , water hydrolysis at the interface 31 , and liquid dewetting leaving behind hydration shell ( i.e ., the residues of liquids and contained ions) 37 . There is an important yet overlooked fact that ion transfer caused by liquid residues inevitably occurs because the previously exploited surfaces always adsorb the liquids during their contact 5 , and these ions are difficult to measure directly, especially on hydrophobic surfaces like PTFE 19 .…”
Section: Resultsmentioning
confidence: 99%
“…Nevertheless, such a view fails to elucidate how electron transfer is dictated by surface properties, which is crucial for controlling both the polarity and magnitude of static charges generated in liquid-solid CE. Meanwhile, existing studies also overlook the possibility that transferred ions may come from liquid residues on surfaces 37 since exploited solid surfaces exhibiting hydrophilicity or low hydrophobicity (usually with a contact angle of <120 o ) inevitably adsorb liquids and ions contained 5 , limiting its applicability to the superhydrophobic surfaces that exhibit strong repellence to liquids. Fig.…”
Liquid-solid contact electrification (CE) is essential to diverse applications. Exploiting its full implementation requires an in-depth understanding and fine-grained control of charge carriers (electrons and/or ions) during CE. Here, we decouple the electrons and ions during liquid-solid CE by designing binary superhydrophobic surfaces that eliminate liquid and ion residues on the surfaces and simultaneously enable us to regulate surface properties, namely work function, to control electron transfers. We find the existence of a linear relationship between the work function of superhydrophobic surfaces and the as-generated charges in liquids, implying that liquid-solid CE arises from electron transfer due to the work function difference between two contacting surfaces. We also rule out the possibility of ion transfer during CE occurring on superhydrophobic surfaces by proving the absence of ions on superhydrophobic surfaces after contact with ion-enriched acidic, alkaline, and salt liquids. Our findings stand in contrast to existing liquid-solid CE studies, and the new insights learned offer the potential to explore more applications.
“…5a ). Previous studies have presented that ions on solid surfaces typically originate from various sources 42 , mainly including ionization reaction on chemically active solid surfaces 20 , water hydrolysis at the interface 31 , and liquid dewetting leaving behind hydration shell ( i.e ., the residues of liquids and contained ions) 37 . There is an important yet overlooked fact that ion transfer caused by liquid residues inevitably occurs because the previously exploited surfaces always adsorb the liquids during their contact 5 , and these ions are difficult to measure directly, especially on hydrophobic surfaces like PTFE 19 .…”
Section: Resultsmentioning
confidence: 99%
“…Nevertheless, such a view fails to elucidate how electron transfer is dictated by surface properties, which is crucial for controlling both the polarity and magnitude of static charges generated in liquid-solid CE. Meanwhile, existing studies also overlook the possibility that transferred ions may come from liquid residues on surfaces 37 since exploited solid surfaces exhibiting hydrophilicity or low hydrophobicity (usually with a contact angle of <120 o ) inevitably adsorb liquids and ions contained 5 , limiting its applicability to the superhydrophobic surfaces that exhibit strong repellence to liquids. Fig.…”
Liquid-solid contact electrification (CE) is essential to diverse applications. Exploiting its full implementation requires an in-depth understanding and fine-grained control of charge carriers (electrons and/or ions) during CE. Here, we decouple the electrons and ions during liquid-solid CE by designing binary superhydrophobic surfaces that eliminate liquid and ion residues on the surfaces and simultaneously enable us to regulate surface properties, namely work function, to control electron transfers. We find the existence of a linear relationship between the work function of superhydrophobic surfaces and the as-generated charges in liquids, implying that liquid-solid CE arises from electron transfer due to the work function difference between two contacting surfaces. We also rule out the possibility of ion transfer during CE occurring on superhydrophobic surfaces by proving the absence of ions on superhydrophobic surfaces after contact with ion-enriched acidic, alkaline, and salt liquids. Our findings stand in contrast to existing liquid-solid CE studies, and the new insights learned offer the potential to explore more applications.
“…At the outlet, the solution flowed through a Teflon tube (length 20 cm and inner diameter 0.38 mm), where the water drops picked up a net positive charge due to the charge separation that occurs in the electrical double layer. 39,40,45,46 Fig. 1(d) shows the self-assembly of the charged drops, which exhibit more order than the polarized case (Fig.…”
Water drops floating at an interface can be self-assembled and controlled using electrostatic effects. Uncharged drops can be moved around as desired, while charged drops exhibit spontaneous directed motion.
“…A liquid drop sliding down an inclined surface can become electrically charged, but only if the surface is hydrophobic (water repelling). Now researchers have developed an analytical model that makes quantitative predictions for the process and that explains why a hydrophobic surface is necessary [1]. The model, validated with experiments, shows that the large contact angle between the liquid surface and a hydrophobic solid surface has a strong Nature's charger.…”
mentioning
confidence: 99%
“…(Darker green shades indicate higher charge density, and the black curves are streamlines indicating the fluid flow as the drop moves to the right.) Credit: A. D. Ratschow et al [1] edges of the interface, which in turn affects the electric field. And finally, as the rear edge of the drop arrives over a patch of the surface, it deflects the fluid upward, which moves protons upward and distorts the electric field.…”
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