Thermochemical performance of ceria coated-macroporous 3D-printed black zirconia structures for solar CO/H2 fuels production

The use of macroporous structured ceria for the solar thermochemical splitting of CO 2 and H 2 O to produce clean fuels through two-step redox cycles was investigated. The research aimed to assess the reactivity of 3D-printed black zirconia gyroid structures coated with a microporous layer of pure CeO 2 for producing CO and H 2 . Such porous designs are intended to increase both the absorption of solar radiation and the available surface area for the solid-gas reaction. It was observed that the structure degraded more at the top of the reactor cavity, where the formation of Ce x Zr 1−x O 2 solid solutions occurred at the coating/substrate interface. Besides, the porous ceria structure remained after redox cycles in the samples not directly exposed to solar radiation. Consequently, the solar reactor achieved CO and H 2 production rates of up to 5.4 and 1.9 mL min −1 g −1 with fuel yield over 0.2 mmol g −1 , and the material maintained its performance over several consecutive cycles without any loss of reactivity. This indicates a strong potential for producing solar fuels at a large facility using custom 3D-printed ceria-coated structures. Experimental setup for conducting thermochemical cycles using developed ceria-coated 3D-printed black zirconia structures. • Porous black ZrO 2 structures coated with CeO 2 were investigated for CO/H 2 production. • 3D-printed cubes were subjected to thermochemical cycles in a solar-heated reactor. • The porous hierarchical-ordered structures enhanced the thermochemical reactor performance. • Temperature increase or pressure decrease on reduction favored fuel yield. • Peak CO and H 2 fuel production rates of 5.4 and 1.9 mL min −1 g −1 were reached.