Thermophysical and optical properties of NiCo2O4@ZrO2: A potential composite for thermochemical processes

Abstract

The use of solar energy through thermochemical processes is an important approach to drive endothermic reactions to produce solar fuels such as hydrogen or syngas. This work reports the preparation and the thermophysical characterization of a porous composite based on zirconium dioxide (ZrO2) and nickel cobaltite (NiCo2O4) nanoparticles for applications in thermochemical processes at high temperatures. The ZrO2 supports were modified with NiCo2O4 nanoparticles by a low-cost and straightforward impregnation process following by thermal treatment at 773 K. The impregnated NiCo2O4 obtained is formed by nanoparticles with an average size of 50 nm favoring a complete and homogenous covering of ZrO2 supports. The thermal properties of ZrO2 supports and NiCo2O4@ZrO2 composites were evaluated in the temperature range from 300 to 1250 K. Besides, the solar absorbance and thermal emittance values were measured. After depositing the nickel cobaltite nanoparticles in the supports, it has been observed that the thermal properties have changed slightly so that the added nanoparticles do not significantly change the thermal performance of the materials. The nickel cobaltite nanoparticles deposited on the surface of the ZrO2 supports causes a strong increase in solar absorbance. This improves the efficiency of solar thermal conversion. Our results have shown that NiCo2O4@ZrO2 has excellent characteristics to be used in solar thermochemical processes.