CO₂ Conversion to Butene via a Tandem Photovoltaic–Electrochemical/Photothermocatalytic Process: A Co-design Approach to Coupled Microenvironments

Here, we developed a tandem, unassisted, solar-driven electrochemical and photothermocatalytic process for the single-pass conversion of CO<sub>2</sub> to butene using only simulated solar irradiation as the energetic input. The two-step process involves electrochemical CO<sub>2</sub> reduction (CO<sub>2</sub>R) to ethylene followed by ethylene dimerization to butene. We assessed two unassisted electrochemical setups to concentrate ethylene in the CO<sub>2</sub>R reactor, achieving concentrations up to 5.4 vol.% with 1.8% average solar-to-ethylene conversion and 5.6% average CO<sub>2</sub>-to-ethylene single-pass conversion under 1-sun illumination. When passed through the photothermocatalytic ethylene oligomerization reactor, we generated 600 ppm of butene under 3-sun illumination. Through analysis of this process, we identified that the presence of H<sub>2</sub>, CO, and H<sub>2</sub>O leads to rapid deactivation of the Ni-based ethylene oligomerization catalyst.