CO2 Electroreduction Using Cu-Supported Co3O4 Catalyst for Multielectron Product Formation via Metal–Support Interaction

In this work, the concept of metal–support interaction to develop an electrocatalyst based on copper/copper oxide is utilized. Cobalt oxide is selected as the oxide support, synthesized by the solution combustion method, upon which copper nanoparticles are dispersed using the formaldehyde reduction method. Different concentrations of Cu (1%, 2.5%, 5%, 10%, and 15%) are loaded over the support, among which the 2.5% Cu/Co<inf>3</inf>O<inf>4</inf> system works the best by giving a Faradaic efficiency of 34%. Detailed catalyst characterizations are performed using X-ray diffractometer, field emission scanning electron microscopy, inductively coupled plasma optical emission spectrometer, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy analyses. Electrochemical studies are carried out to estimate the catalyst's activity using techniques such as cyclic voltammetry and chronoamperometry. High-value gaseous (CO, CH<inf>4</inf>) and liquid product (CH<inf>3</inf>CH(OH)CH<inf>3</inf>) are identified during the CO<inf>2</inf> electroreduction process. Liquid isopropyl alcohol (IPA) forms at a very low overvoltage (≈200 mV). Pre- and postreaction XRD shows slight shifting of peaks. In XPS, pre- and postspectra reveal complete and partial oxidation of Cu⁺²/Cu⁺ and Co<inf>3</inf>O<inf>4</inf>, respectively. Electrocatalytic activity of the catalyst is also compared with its precursors (Cu and Co<inf>3</inf>O<inf>4</inf>), and the activity of these precursors is much less compared to that of the Cu/Co<inf>3</inf>O<inf>4</inf> system due to metal–support interaction.