CO<sub>2</sub> Conversion to Butene via a Tandem Photovoltaic–Electrochemical/Photothermocatalytic\nProcess: A Co-design Approach to Coupled Microenvironments

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