Emerging Hydrovoltaic Technology
Dr. Wanlin GUO, Academician of Chinese Academy of Sciences, Chair Professor in mechanics and nanoscience, founder and director of the Key Laboratory of Intelligent Nano Materials and Devices of Ministry of Education and the Institute of Nanoscience of Nanjing University of Aeronautics and Astronautics. His current research focuses on intelligent nano materials and devices, novel conception and technology for efficient energy conversion, molecular physical mechanics for neuronal signaling and molecular biomimics, as well as strength and safety of aircraft and engine. He has published more than 400 peer-reviewed journal papers on Nature series, Phys. Rev. Lett., J. Am. Chem. Soc., Adv. Mater., J. Mech. Phys. Solids, Nano Lett., etc. He received the National Science Foundation of China for Distinguished Young Scholars in 1996 and the honor of Cheung Kong Scholars in 1999. In 2012, he obtained the National Nature Science Prize of China.
Water is not only the essence of life, but also the largest energy carrier on earth1. Water covers about 70% of the earth's surface, absorbing 70% of the solar energy arriving the earth, and in the atmosphere it can exist in liquid, gaseous and solid states. In human history, through a variety of scientific principles, such as running water driven wheel, steam locomotives, water driven generator as well as the electrokinetic effects, the potential energy or kinetic energy of water can be converted into useful mechanical motion and electrical energy according to the principles of classical mechanics and electromagnetic dynamics. In recent years, we have theoretically and experimentally investigated the fluid-solid-electric coupling functionalization of graphene and other two-dimensional materials2-7. It is found that carbon nanostructures can generate electricity from water energy by direct interaction with water3,4, even by natural water evaporation from cheap carbon nanomaterials5, a phenomenon that we termed as hydrovoltaic effect6,7, which potentially extends the technical capability of water energy harvesting and enables creation of self-powered devices. Here, starting by presenting the water energy on the earth, fundamental properties of water and water-solid interfaces, we discussed basic mechanisms of harvesting water energy by carbon nanostructured materials and key aspects pertaining to water-carbon interaction. Experimental advances in generating electricity from water flows, waves, especially natural water-evaporation were then reviewed to show correlations in mechanisms and potential for integration, offering a prospect of harvesting energy from the nature cycle of water on the earth. Main challenges in promoting the energy conversion efficiency and scaling up the output power will be outlined, and finally discuss potential development and applications of the hydrovoltaic technology.
1.Penman, H. L. Natural Evaporation from Open Water, Bare Soil and Grass. Proc. R. Soc. Lond. A193, 120-145 (1948).
2.Yin, J., Zhang, Z., Li, X., Zhou, J. & Guo, W. Harvesting Energy from Water Flow over Graphene? Nano Lett.12, 1736-1741 (2012).
3.Yin, J., Zhang, Z., Li, X., Yu, J., Zhou, J., Chen, Y. & Guo, W. Waving potential in graphene. Nat. Commun.5, 3582 (2014).
4.Yin, J., Li, X., Yu, J., Zhang, Z., Zhou, J. & Guo, W. Generating electricity by moving a droplet of ionic liquid along graphene. Nat. Nanotechnol.9, 378 (2014).
5.Xue, G., Xu, Y., Ding, T., Li, J., …, Zhou, J. & Guo, W. Water-evaporation-induced electricity with nanostructured carbon materials. Nat. Nanotechnol.12, 317 (2017).
6.Zhang, Z., Li, X., Yin, J., Xu, Y.,Fei, W., Xue, M., Wang, Q., Zhou J. & Guo, W. Emerging hydrovoltaic technology. Nat. Nanotechnol.13, pages1109–1119 (2018.12.6).
7.郭万林张助华, 水伏科学与技术的召唤. 科学通报63, 2804-2805 (2018).