title: Electrochemically controlled formation and growth of hydrogen nanobubbles.
abstract: Electrogenerated microscale bubbles that are confined at the electrode surface have already been extensively studied because of their significant influence on electrochemistry. In contrast, as far as we know, whether nanoscale bubbles exist on the electrode surface has not been experimentally confirmed yet. Here, we report the observation of electrochemically controlled formation and growth of hydrogen nanobubbles on bare highly oriented pyrolytic graphite (HOPG) surface via in-situ tapping mode atomic force microscopy (TMAFM). By using TMAFM imaging, we observed that electrochemically generated hydrogen gas led to the formation of nanobubbles at the HOPG surface. We then employed a combination of techniques, including phase imaging, ex-situ degassing, and tip perturbation, to confirm the gas origin of such observed nanobubbles. We further demonstrated that the formation and growth of nanobubbles could be well controlled by tuning either the applied voltage or the reaction time. Remarkably, we could also monitor the evolution process of nanobubbles, that is, formation, growth, coalescence, as well as the eventual release of merged microbubbles from the HOPG surface.
authors.affiliation: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Zhang
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xuehua
authors.initials: X
authors.lastname: Zhang
authors.forename: Zhaoxia
authors.initials: Z
authors.lastname: Li
authors.forename: Guangxia
authors.initials: G
authors.lastname: Shen
authors.forename: Ming
authors.initials: M
authors.lastname: Ye
authors.forename: Chunhai
authors.initials: C
authors.lastname: Fan
authors.forename: Haiping
authors.initials: H
authors.lastname: Fang
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
mesh_terms: D004563:Electrochemistry; D004566:Electrodes; D005740:Gases / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013464:Sulfuric Acids / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D005740:Gases; D012996:Solutions; D013464:Sulfuric Acids; D014867:Water; D006108:Graphite; D006859:Hydrogen; C033158:sulfuric acid