The Effect of Temperature on the Cation‐Promoted Electrochemical CO₂ Reduction on Gold

Abstract

Electrochemical reactions in general, and the CO 2 reduction reaction (CO2RR) in particular, are commonly studied at room temperature. However, practical electrolysers may use elevated temperatures. There is currently a lack of fundamental understanding of the effect of temperature on the CO2RR. Here, we performed temperature-dependent studies on the CO2RR on a relatively simple electrode material, namely gold, to obtain insights into how temperature influences this reaction and the competing hydrogen evolution reaction. A rotating ring disk electrode setup was used to show that the CO2RR activity and selectivity increased with temperature, and to obtain kinetic parameters such as the apparent activation energy and transfer coefficient. The magnitude of the temperature effect and the activation energy was affected by both the cation identity and concentration in the electrolyte. Moreover, the positive effect of temperature on the kinetics of the CO2RR was counteracted by the lower CO 2 solubility, making efficient mass transport even more important at higher temperatures.

Understanding Cation Effects on the Hydrogen Evolution Reaction

“…Future experimental studies that use kinetic analysis to separate enthalpic and entropic contributions of the reaction medium, as well as spectroscopic studies that probe the structure of the electrochemical interface in different electrolytes, would be of great value. 20,73,74 Continued development of computational models that give higher fidelity of electrocatalytic systems would also help contribute to this under-…”

“…In this work, we hope to have contributed to this understanding. Future experimental studies that use kinetic analysis to separate enthalpic and entropic contributions of the reaction medium, as well as spectroscopic studies that probe the structure of the electrochemical interface in different electrolytes, would be of great value. ,, Continued development of computational models that give higher fidelity of electrocatalytic systems would also help contribute to this understanding, and clear connections between experiments and theory will help maximize the utility of both . Finally, we hope understanding the role alkali metal cations play in the “simple” hydrogen evolution reaction can provide insights for subsequent studies over more complicated catalytic materials and more complicated (electro)­chemical reactions.…”

Highly Selective Reduction of CO2 to Methane Induced by Subzero Depression of the Electrode Surface Temperature

“…An important energy storage method is electrochemical reduction of CO 2 , which is particularly attractive owing to atmospheric carbon consumption during fuel production. , In typical CO 2 reduction reactions (CO2RRs), product selectivity control has been nearly impossible to achieve, due to the complexity of the reaction including the competitive proton reduction pathway. − Copper is the sole catalyst to produce appreciable amounts of hydrocarbons and alcohols via CO2RR; however, the CO2RR on copper generally produces a variety of products, separation of which is an added layer of challenge . Much less effort was spent on tuning variables pertinent to the surroundings of the catalyst active sites (e.g., the electrolyte and temperature) compared to numerous synthetic strategies developed for engineering of copper structures. − A handful of accounts highlighted that lowering of the electrode bath temperature enhanced methane selectivity; , however, these designs were typically associated with significantly increased overpotentials to drive appreciable current density due to the increased solution resistance in chilled baths. ,, …”

“…To the best of our knowledge, this is the first account of probing an electrode surface temperature effect on CO2RR product selectivity. In a handful of precedents, [17][18][19][20]31 extremely high electrolyte concentrations were mandated in order to prevent freezing of the solution. The current design employed in this work permitted the investigation of surface temperatureselectivity correlation at typical CO2RR electrolyte strengths of 0.1 M. The reactor design adopted here adds to a typical CO2RR reactor a thermoelectric element for surface temperature depression and a thermometer for monitoring of the bath temperature in situ (see also Figure S1 and Figures S6−S8).…”

“…To the best of our knowledge, this is the first account of probing an electrode surface temperature effect on CO2RR product selectivity. In a handful of precedents, − , extremely high electrolyte concentrations were mandated in order to prevent freezing of the solution. The current design employed in this work permitted the investigation of surface temperature-selectivity correlation at typical CO2RR electrolyte strengths of 0.1 M.…”