Insight into Electrochemical Promotion of Cu/Co3O4 Catalysts for the Reverse Water Gas Shift Reaction

In this study, Copper-modified Co3O4 (Cu/Co3O4) catalysts were investigated for the reverse water gas shift (RWGS) reaction at 200-400℃ under different CO2:H2 ratios. It was found that the electrocatalytic performance of Co3O4 was improved by loading 4 weight percent (wt.%) Cu nanoparticles (average size: 13 nm), which could be then used as an electrode in electrochemical promotion of catalysis (EPOC) studies. Under the applied voltages of +2 V and -1 V, the catalytic rates were suppressed and increased by about 40% and 14%, respectively. This was due to the changes in the active oxidation states of Cu and Co caused by O2- migration under polarization, as confirmed by XPS, XRD, and cyclic voltammetry (CV). The study also revealed that the exchange current density (i0) was counter-correlated with the open-circuit catalytic rate (r0) and could serve as an informative tool for predicting the catalytic rate, which was demonstrated for the first time in the instance of RWGS reaction.