Enhancing CO ₂ Splitting via Plasma Catalysis: Impact of Electrode Design and Catalyst

The CO2 splitting reaction, which converts CO2 into CO and O2, is a straightforward method for CO2 utilization. However, it poses significant challenges in conventional thermal catalysis, as it is strongly endothermic. Nonthermal plasma catalysis offers a promising strategy for achieving efficient CO2 splitting under mild conditions. Nevertheless, the effects of the electrode temperature and electric field on the CO2 activation in the plasma reactor are still unclear. In this study, we differentiate the temperature effect from the electric field effect by comparatively examining plasma reactions with stainless-steel electrodes (SSE), circulating water electrodes (CWE), and specially designed static water electrodes (SWE). Using water electrodes markedly enhances CO2 conversion, which can be explained by the suppressed reverse reaction rate (CO oxidation) at the lower temperature. Furthermore, Lissajous figures with various electrodes indicate that water electrodes increase the effective capacitance of the reactor, thereby strengthening the electric field and facilitating the CO2 dissociation. It is worth noting that the catalyst is still very important with the electrode engineering. Packing TiO2 significantly alters the plasma chemistry and boosts CO2 dissociation by stabilizing adsorbed CO2 species as monodentate and bidentate carbonates, as evidenced by in situ DRIFTS studies. This work provides critical insights into the electrode design for plasma catalytic CO2 splitting, advancing sustainable strategies for CO2 utilization, and contributing to carbon-neutral energy solutions.