Yang Shanshan, Su Yudan, Xu Ying, Wu Qiong, Zhang Yuanbo, Raschke Markus B, Ren Mengxin, Chen Yan, Wang Jianlu, Guo Wanlin, Ron Shen Y, Tian Chuanshan
Department of Physics, State Key Laboratory of Surface Physics and Key Laboratory of Micro- and Nano-Photonic Structures (MOE) , Fudan University , Shanghai 200433 , China.
Collaborative Innovation Center of Advanced Microstructures , Nanjing 210093 , China.
J Am Chem Soc. 2018 Oct 24;140(42):13746-13752. doi: 10.1021/jacs.8b07778. Epub 2018 Oct 10.
Graphene-based electric power generation that converts mechanical energy of flow of ionic droplets over the device surface into electricity has emerged as a promising candidate for blue-energy network. Yet the lack of a microscopic understanding of the underlying mechanism has prevented ability to optimize and control the performance of such devices. This requires information on interfacial structure and charging behavior at the molecular level. Here, we use sum-frequency vibrational spectroscopy to study the roles of solvated ions, graphene, surface moiety on substrate and water molecules at the aqueous solution/graphene/polymer interface. We discover that the surface dipole layer of the neutral polymer is responsible for ion attraction toward and adsorption at the graphene surface that leads to electricity generation in graphene. Graphene itself does not attract ions and only acts as a conducting sheet for the induced carrier transport. Replacing the polymer by an organic ferroelectric substrate could allow switching of the electricity generation with long durability. Our microscopic understanding of the electricity generation process paves the way for the rational design of scalable and more efficient droplet-motion-based energy transducer devices.
基于石墨烯的发电技术，能够将离子液滴在器件表面流动的机械能转化为电能，已成为蓝色能源网络中一个有前景的候选技术。然而，由于缺乏对其潜在机制的微观理解，阻碍了优化和控制此类器件性能的能力。这需要分子水平上的界面结构和充电行为信息。在此，我们使用和频振动光谱来研究水溶液/石墨烯/聚合物界面处溶剂化离子、石墨烯、基底表面部分以及水分子的作用。我们发现中性聚合物的表面偶极层负责离子向石墨烯表面的吸引和吸附，从而导致石墨烯中产生电流。石墨烯本身并不吸引离子，仅作为诱导载流子传输的导电片。用有机铁电基底替代聚合物可以实现具有长期耐久性的发电切换。我们对发电过程的微观理解为合理设计可扩展且更高效的基于液滴运动的能量转换器件铺平了道路。
