Recent experiments have demonstrated that moving water droplets on polymer-supported graphene can generate electric voltages in graphene.Here,we perform a multi-scale analysis on the mechanism of the generated voltage...Recent experiments have demonstrated that moving water droplets on polymer-supported graphene can generate electric voltages in graphene.Here,we perform a multi-scale analysis on the mechanism of the generated voltages on the basis of an interplay among the substrate,graphene and ionic water.We find that the attraction of ions in water by substrate dipoles drives charge redistribution in graphene,forming an electric triple layer(ETL)at the water/graphene/substrate interface,made of an ion layer fixed on graphene,an image charge layer in graphene and a counterion layer in water.As a droplet moves on graphene,dynamic formation of the ETL at its front end drives a flow of charge in graphene.Using Langmuir adsorption theory combined with ab initio calculations,we determine the ion concentration in the ETL and estimate the amount of charge that each ion can draw in graphene.Then,the electric current in graphene is formulated in terms of ion concentration,droplet velocity,graphene thickness and density of substrate dipoles,which well reproduces experimentally measured currents in graphene.These results underscore the importance of tailoring substrate dipoles in optimizing the performance of devices for water energy harvesting and promoting practical applications.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0705400)National NSF of China(Grant Nos.12261160367,12225205,and 22073048)+1 种基金A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,Natural Science Foundation of Jiangsu Province(Grant No.BK20220872)Jiangsu Funding Program for Excellent postdoctoral talent(Grant No.2022ZB232),The computations were in part performed at the Highperformance Computational Center at NUAA.
基金This work was supported by the National and Jiangsu Province Natural Science Foundation(Grant Nos.T2293691,T2293692,and BK20212008)of ChinaNational Key Research and Development Program of China(Grant No.2019YFA0705400)+3 种基金China Postdoctoral Science Foundation(Grant No.2021M701703)Jiangsu Funding Program for Excellent postdoctoral talent(Grant No.2022ZB211),the Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures(Grant No.MCMS-I-0422K01)the Fundamental Research Funds for the Central Universities(Grant No.NJ2022002)the Fund of Prospective Layout of Scientific Research for NUAA(Nanjing University of Aeronautics and Astronautics).
基金supported by the National Key Research and Development Program of China (2019YFA0705400)the National Natural Science Foundation of China (11772153 and22073048)+2 种基金the Natural Science Foundation of Jiangsu Province(BK20190018)the Fundamental Research Funds for Central Universities (NJ2020003, NZ2020001, NP2019301, NJ2019002 and NC2018001)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Recent experiments have demonstrated that moving water droplets on polymer-supported graphene can generate electric voltages in graphene.Here,we perform a multi-scale analysis on the mechanism of the generated voltages on the basis of an interplay among the substrate,graphene and ionic water.We find that the attraction of ions in water by substrate dipoles drives charge redistribution in graphene,forming an electric triple layer(ETL)at the water/graphene/substrate interface,made of an ion layer fixed on graphene,an image charge layer in graphene and a counterion layer in water.As a droplet moves on graphene,dynamic formation of the ETL at its front end drives a flow of charge in graphene.Using Langmuir adsorption theory combined with ab initio calculations,we determine the ion concentration in the ETL and estimate the amount of charge that each ion can draw in graphene.Then,the electric current in graphene is formulated in terms of ion concentration,droplet velocity,graphene thickness and density of substrate dipoles,which well reproduces experimentally measured currents in graphene.These results underscore the importance of tailoring substrate dipoles in optimizing the performance of devices for water energy harvesting and promoting practical applications.
