On the behavior of a water electrolysis cell in a DC circuit

Abstract

The electrolysis of water using a DC circuit is a familiar physical science experiment and the empirical details of the process, especially in terms of the chemistry, are well known. There are however, long-standing questions in regard to the specific role played by the circuit itself and the electrolyte. Recent empirical studies of an electrolysis cell as a circuit element have revealed what we see as clues towards understanding the cell’s behavior electrodynamically (Shen M et al 2011 Int. J. Hydrog. Energy 36 14335; Sun C-W and Hsiau S-S 2018 J. Electrochem. Sci. Technol. 9 99). For example, the cell is observed to be non-conductive below a threshold in the difference of potential, and once it becomes conductive the current is proportional to the difference between the applied voltage and the threshold, not the applied voltage. This type of non-Ohmic behavior guides our modeling of the cell in two steps. The first is the analysis of an equivalent circuit that captures the observed behavior. The second is an examination of the charge distributions within the double layers near the electrodes that polarize the cell. This polarization renders the cell non-conductive below the threshold, and its lingering effects explain the overall non-Ohmic behavior once conduction is possible. In addition, the energy transfer process required to power the cell, we find, is suggestive of non-classical (i.e. quantum mechanical) mechanisms.