Harvesting Energy from Water Flow over Graphene

http://pubs.acs.org/doi/abs/10.1021/nl2011559

Prashant Dhiman†, Fazel Yavari†, Xi Mi‡, Hemtej Gullapalli§, Yunfeng Shi‡, Pulickel M. Ajayan§, and Nikhil Koratkar*†‡

^†Department of Mechanical, Aerospace, and Nuclear Engineering, ^‡Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States

Department of Mechanical and Materials Engineering,Rice University, Houston, Texas, United States

Nano Lett., 2011, 11 (8), pp 3123 - 3127

DOI: 10.1021/nl2011559

Publication Date (Web): July 12, 2011

Copyright © 2011 American Chemical Society

E-mail: koratn@rpi.edu.

Water flow over carbon nanotubes has been shown to generate an induced voltage in the flow direction due to coupling of ions present in water with free charge carriers in the nanotubes. However, the induced voltages are typically of the order of a few millivolts, too small for significant power generation. Here we perform tests involving water flow with various molarities of hydrochloric acid (HCl) over few-layered graphene and report order of magnitude higher induced voltages for graphene as compared to nanotubes. The power generated by the flow of 0.6 M HCl solution at 0.01 m/sec was measured to be 85 nW for a 30 × 16 μm size graphene film, which equates to a power per unit area of 175 W/m². Molecular dynamics simulations indicate that the power generation is primarily caused by a net drift velocity of adsorbed Cl^– ions on the continuous graphene film surface.

Keywords:

Graphene; energy harvesting; water flow; surface ion hopping