Electrochemical double layer near polar reduced graphene oxide electrode: Insights from molecular dynamic study

Reduced graphene oxide (rGO) has emerged as an attractive choice for electrochemical double layer capacitors. Based on the accurate atomic partial charge distribution determined by density functional theory calculations, the electrochemical double layer structural and capacitive properties at the rGO/NaCl aqueous electrolyte interface are studied using the molecular dynamic simulations. Due to the charge redistribution mainly around oxygen functional groups, rGO will form a strong polar surface. It will significantly change the arrangement of surrounding water molecules through a hydrogen bond like interaction. The change of dipole orientation of water will induce corresponding net charge redistribution, leading to a change of potential of zero charge of rGO electrode. The polarization interaction also restricts the orientation of electrolyte molecules and weakens their mobility, resulting in the decrease of integral capacitance value of rGO with increasing of functional groups concentration. This work about electrochemical double layer near polar rGO electrode could offer a reasonable guidance for future performance improvements of electrochemical double layer capacitors. (C) 2015 Elsevier Ltd. All rights reserved.