page_title: Virtual breakdown mechanism
section_title: Electric field distribution
hierarchical_section_title: Virtual breakdown mechanism / Electric field distribution
caption_attribution_description: English: Schematic diagram of potential distribution comparison between macrosystem and nanogap cells
context_page_description: Virtual breakdown mechanism is a concept in the field of electrochemistry. In electrochemical reactions, when the cathode and the anode are close enough to each other, the double layer regions from the two electrodes can be overlapped, forming large electric field uniformly distributed inside the entire electrode gap. Such high electric field can significantly enhance the ion migration inside bulk solution, and thus facilitate the entire reaction rate, performing like "breakdown" of the reactant. However, it is fundamentally different from the meaning of traditional "breakdown".
  Virtual breakdown mechanism is discovered in 2017 when researchers studied pure water electrolysis based on deep-sub-Debye-length nanogap electrochemical cells. Furthermore, researchers found the size effect of the gap distance between cathodes and anodes to the performance of electrochemical reactions.
context_section_description: The fundamental difference between traditional cells and nanogap cells are their electric potential distribution. This is the premise of the "virtual breakdown" effect.
  For electrochemical reactions with high-concentration electrolyte in macrosystem, the Debye-length is quite small. Due to the screening effect, almost all the potential drop is confined within such small Debye-length region (or double layer region). The potential in bulk solution (far from the electrodes) would not change too much, meaning that there is nearly zero electric field inside the bulk solution. However, when we put the counter electrode within the Debye-length region (i.e., nanogap electrochemical cells), two double layers from anode and cathode have to be overlapped with each other. The electrostatic potential inside the entire gap can change continuously and dramatically, meaning that huge electric field can be uniformly distributed in the entire gap.
caption: Schematic diagram of potential distribution comparison between macrosystem and nanogap cells
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