Increasing sensitivity of formate detection using formate selective catalyst and redox cycling reaction of interdigitated array microelectrode

Abstract

Electrochemical $CO_2$ reduction reactions are attracting much attention because it can convert $CO_2$ into economically valuable products. So, techniques for quickly detecting and screening $CO_2$ products are increasingly important to find the optimal catalyst which can selectively convert $CO_2$ to the desired chemical. Here, we suggested a new possibilities for measuring $CO_2$ reduction products using the redox cycling reaction without using conventional methods like GC and LC. By electroplating indium which is known as the one of the formate selective catalysts on the one array of IDAE, one of the redox cycling devices, and inducing a redox cycling reaction of formate, not only could we increase the sensitivity for detecting formate, but also we see the same redox cycling reaction of formate when there are only $CO_2$ in the bulk solution. In the experiment using indium bulk sample, we found that -1.4V vs RHE was the most suitable potential for formate formation, and this was also confirmed in the results from the formate oxidation peak obtained using In-Pt IDAE. In addition, we calculated the faraday efficiency of formate from the formate oxidation peak based on several assumptions, and found that the value is almost similar to those obtained from HPLC.