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The hydrogenation of CO2 is a reaction of key technological and environmental importance, as it contributes to the sustainable production of fuels while assisting in the reduction of a major greenhouse gas. The reaction has received substantial attention over the years within the catalysis and electrocatalysis communities. In this respect, the electrochemical promotion of catalysis (EPOC) has been applied successfully to the CO2 hydrogenation reaction to improve the catalytic activity and selectivity of conductive films supported on solid electrolytes. However, designing an effective electrocatalytic reactor remains a challenge due to the connections required between the electrodes and the external potentiostat/galvanostat. This drawback could be alleviated if the catalytic reaction occurs in a reactor that simultaneously operates as a power generator. In this work, the Electrochemical Promotion of the CO2 hydrogenation reaction in a low-temperature solid oxide electrolyte fuel cell (SOFC) reactor is studied using yttria-stabilized zirconia (YSZ) and a platinum (Pt) electrode catalyst. The system has been studied in two distinct operation modes: (i) when the necessary energy for the electrochemical promotion is produced through the parallel reaction of H2 oxidation (galvanic operation) and (ii) when a galvanostat/potentiostat is used to impose the necessary potential (electrolytic operation). The performance of the fuel cell declines less than 15% in the presence of the reactant mixture (CO2 and H2) while producing enough current to conduct EPOC experiments. During the electrolytic operation of the electrochemical cell, the CO production rate is significantly increased by up to 50%.

Electrochemical promotion was used to modify the activity and selectivity of a Rh catalyst electrode in the CO2 hydrogenation reaction. The experiments were carried out in a temperature range of 350–430 °C at ambient pressure and at different CO2 to H2 gas feeding ratios (1:2 to 4:1). The only reaction products observed were CO and CH4, both under open- and closed-circuit conditions. The CH4 formation rate was found to increase with both positive and negative potential or current application. The CO formation rate followed the opposite trend. The selectivity to CH4 increased under high values of hydrogen partial pressure and decreased at high pressures of CO2. The results demonstrate how electrochemical promotion can be used to finely tune activity and selectivity for a reaction of high technical and environmental importance.