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

•The porous skeleton of SiC and Si3N4 synthesized by the foam impregnation method has a good strength and porosities are 35.29 % and 54.39 %, respectively.•In the solar thermochemical system experiment, the highest instantaneous CO was 410 μmol/gNiFe2O4@SiC.•The average CO2 conversion rate of direct CO2-to-CO through NiFe2O4@SiC over seven cycles was 11.2% in the solar thermochemical system experiment.•The CO yield of NiFe2O4-supported SiC is twice that of SiC skeleton, based on photothermal synergy of support and catalyst. The solar-driven thermochemical CO2-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 CO2-to-CO conversion are the most important challenges associated with the thermochemical CO2-splitting approach and technological upscaling to large-scale applications. This study presented the development of NiFe2O4 oxygen carriers, the synthesis method of SiC and Si3N4 supports, and solar-to-fuel processing of the newly prepared materials through CO2-splitting under a highly concentrated solar radiative heat flux. The newly synthesized NiFe2O4@SiC porous redox material resulted in higher solar energy absorption and CO2 conversion capability with an instantaneous CO production of 410 μmol/g and direct CO2-to-CO conversion rate of 18.1 % at 1073–1273 K reaction temperature. The media composite of NiFe2O4@SiC exhibited high-temperature thermal changes, good thermochemical reaction stability, and a higher CO production rate through six redox cycles compared to NiFe2O4@Si3N4 porous reacting material. The high oxidation potential and remarkably solar radiative heat flux absorption and thermochemical CO2-splitting capacities of the newly developed materials were demonstrated through experimental analysis. The synergistic effect of the oxygen carriers (NiFe2O4) and substrate materials including SiC and Si3N4 skeletons for CO2-splitting is highlighted. This study provided comprehensive and novel experimental insights that can be used as guidance for theoretical research and application in CO2 conversion into high-value-added energy products.