Preparation and solar thermochemical properties analysis of NiFe2O4@SiC/ @Si3N4 for high-performance CO2-splitting

The solar-driven thermochemical CO 2 -to-CO conversion is an effective way to achieve the mission of carbon peaking and carbon neutrality. However, synthesizing porous reacting materials with excellent thermal stability, hardness and long-term cyclic stability, oxygen exchange capacity, and higher CO 2 -to-CO conversion are the most important challenges associated with the thermochemical CO 2 -splitting approach and technological upscaling to large-scale applications. This study presented the development of NiFe 2 O 4 oxygen carriers, the synthesis method of SiC and Si 3 N 4 supports, and solar-to-fuel processing of the newly prepared materials through CO 2 -splitting under a highly concentrated solar radiative heat flux. The newly synthesized NiFe 2 O 4 @SiC porous redox material resulted in higher solar energy absorption and CO 2 conversion capability with an instantaneous CO production of 410 μmol/g and direct CO 2 -to-CO conversion rate of 18.1 % at 1073–1273 K reaction temperature. The media composite of NiFe 2 O 4 @SiC exhibited high-temperature thermal changes, good thermochemical reaction stability, and a higher CO production rate through six redox cycles compared to NiFe 2 O 4 @Si 3 N 4 porous reacting material. The high oxidation potential and remarkably solar radiative heat flux absorption and thermochemical CO 2 -splitting capacities of the newly developed materials were demonstrated through experimental analysis. The synergistic effect of the oxygen carriers (NiFe 2 O 4 ) and substrate materials including SiC and Si 3 N 4 skeletons for CO 2 -splitting is highlighted. This study provided comprehensive and novel experimental insights that can be used as guidance for theoretical research and application in CO 2 conversion into high-value-added energy products.