Accommodating Solute Diffusion Timescales via Pulsed Plasma Electrolysis

Direct-current plasmas in contact with liquids can serve as electrochemical cathodes to drive challenging reduction reactions in everyday solvents such as water and alcohols without harsh reagents nor solid interfaces via the injection of solvated electrons. However, because of the high reactivity of solvated electrons at the liquid interface, plasma electrolysis often suffers from transport-limited operation, causing poorer yields and energy efficiency. Here, we utilize pulsed plasma currents—essentially controlling the dose, duration, and frequency of electron delivery—to accommodate the slow diffusion of solutes to the reactive, electron-rich interface. We find that the system can be suitably approximated as a diffusion- and current-controlled reaction that is well-described in many electrochemistry textbooks. This analysis, combined with experimental validation, enables one to maintain kinetically-limited and selective operation for systems otherwise prone to transport-limitations.