Digital light processing of hierarchically porous cerium oxide ceramics for CO₂ splitting and fuel production

Solar thermochemical fuel production (STFP) utilizes a two-step oxidation–reduction cycle reaction to convert solar energy into storable and transportable carbon monoxide/hydrogen fuel, and it has attracted considerable attention. Hierarchical porous cerium oxide (CeO₂) materials have excellent redox properties, high-temperature thermal stability, and a large specific surface area. Thus, they are crucial components of the STFP process. However, current manufacturing methods have issues such as high process costs and difficulty in controlling pores. This study uses the digital light processing (DLP) printing method to develop a soluble starch–CeO₂ composite slurry, in which micropores are generated during the subsequent pyrolysis and sintering processes. Hierarchically porous CeO₂ ceramics are obtained with controllable millimeter-scale and micrometer-scale pores. The oxidation–reduction cycle test conducted at 1400–900 °C shows that the structure has good redox ability and high temperature stability, with a cyclic CO production of 100.76 μmol/g (2.257 mL/g) and a strength above 124.21±9.49 MPa. The samples function well without collapsing over 50 redox cycles. This performance is better than that of the ceramics manufactured using conventional methods. This study develops an innovative method of utilizing DLP technology to manufacture hierarchical porous CeO₂ ceramics as redox carriers, thus providing new avenues for using the DLP process to produce solar thermal chemical fuels.