Porous CeO ₂ Ceramics Integrated Multiscale Pores with Enhanced Heat Transfer Capacity for Solar‐Driven Thermochemical CO ₂ Splitting

Abstract The solar‐driven two‐step thermochemical cycle using ceria (CeO 2 ) to split CO 2 into CO offers an efficient way to reduce carbon emissions and utilize renewable energy. A gradient pore‐structured CeO 2 ceramic is proposed to overcome the limited solar absorption of conventional porous CeO 2 ceramics, which restricts solar‐to‐fuel efficiency. The structure, designed via computational fluid dynamics (CFD) and fabricated by digital light processing (DLP) using a water‐in‐oil (W/O) Pickering emulsion, integrates millimeter‐ and micrometer‐scale pores. The resulting ceramic shows uniform temperature distribution and high effective density, suitable for solar‐driven CO production. It has a hierarchical porous structure with interconnected pores, total porosity of 85.77 ± 0.77%, pore sizes centered at 9.0 µm and 0.8–1.5 µm, and a specific surface area of 0.30 ± 0.02 m 2 g −1 . Thermogravimetric analysis over cycles between 1400 and 600 °C yielded 2.450 and 2.394 mL g −1 of CO in the first two cycles. After ten cycles, micropores sintered, but the interconnected structure remained intact. These results highlight the potential of tailored CeO 2 ceramics for solar‐to‐fuel conversion applications and advanced ceramic manufacturing.