Electrocatalysis in non-thermal plasma for energy storage

The Energy Transition requires the development of technologies that allow for efficient energy storage and conversion or allow to decarbonise important industrial processes. Electrochemical processes are inherently energy efficient, but the sluggishness of some electron transfer processes (e.g., the reduction of CO2) often still makes their efficiency not high enough to overcome their cost. Plasma catalysis has also been proposed for some of these processes as it enables the activation of highly stable molecules like CO2 and N2 even at ambient temperatures through the collision of these molecules with highly energetic electrons. The method makes possible the electrification of catalytic processes, avoiding the use of toxic or hazardous chemicals. It has been recently shown that plasmas can act as the electrolyte in an electrochemical cell, which opens the doors to the exciting possibility of joining plasma and electrocatalysis to obtain the best of both worlds. However, these studies either used a flame (a hot plasma) as the electrolyte or lacked a detailed study of the response of the electrode-plasma interface to an applied potential.
We propose a fundamental study of relevant electrochemical processes in plasmas aimed at identifying conditions under which the electrochemical reduction of CO2 to useful products can be achieved efficiently and with good selectivity. We will focus on Cu electrodes because copper is the only material on which the electrochemical reduction of CO2 in aqueous media results in hydrocarbons (with other materials reduction does not go beyond carbon monoxide or formic acid). The project will also involve the design of cells and methodologies to record infrared and optical emission spectra during the electrochemical experiments, with the aim of identifying intermediates and products of the reaction, thereby elucidating reaction mechanisms and product distributions and yields. In a second stage, the deep understanding of the reactions occurring at the electrode-plasma interface will be used to build a lab prototype of a plasma electrolyser converting CO2 to hydrocarbons.
Although we will focus on the reduction of CO2 and the oxidation of hydrogen (the two reactions involved in a cold-plasma CO2 electrolyser aiming at producing hydrocarbons), they will set a world first, and once developed they will establish the standard for similar studies of other reactions in our and other laboratories. Furthermore, because the oxidation of hydrogen must also be one of the half reactions in other relevant processes (e.g., the fixation of nitrogen as ammonia) our work will also provide significant advance towards diversifying the technology to processes other than CO2 reduction.