Virtual Breakdown Mechanism: Field-Driven Splitting of Pure Water for Hydrogen Production

TL;DR

This paper introduces a novel 'virtual breakdown mechanism' enabling efficient pure water electrolysis at nanometer scales, significantly enhancing conductivity and hydrogen production without traditional electrolytes.

Contribution

The study presents the first experimental demonstration of field-driven pure water splitting using nanogap electrochemical cells, revealing a new mechanism distinct from macroscale systems.

Findings

Over 10^5-fold increase in pure water conductivity.

Electrolysis current comparable to or exceeding that of 1 mol/L NaOH.

Successful demonstration of high-efficiency pure water splitting at 37 nm nanogaps.

Abstract

Due to the low conductivity of pure water, using an electrolyte is common for achieving efficient water electrolysis. In this paper, we have broken through this common sense by using deep-sub-Debye-length nanogap electrochemical cells for the electrolysis of pure water. At such nanometer scale, the field-driven pure water splitting exhibits a completely different mechanism from the macrosystem. We have named this process 'virtual breakdown mechanism' that results in a series of fundamental changes and more than 10^5-fold enhancement of the equivalent conductivity of pure water. This fundamental discovery has been theoretically discussed in this paper and experimentally demonstrated in a group of electrochemical cells with nanogaps between two electrodes down to 37 nm. Based on our nanogap electrochemical cells, the electrolysis current from pure water is comparable to or even larger than the current from 1 mol/L sodium hydroxide solution, indicating the high-efficiency of pure water splitting as a potential for on-demand hydrogen production.