Innovative fabrication and absorption enhancement in MgO-stabilized ZrO2/graphene composites

Developing radiative cooling coatings is an efficient and energy-conserving approach for thermal management in electronic devices. Spectral selectivity is crucial to daytime radiative cooling, typically achieved through complex structure or material designs. This work designs a radiative cooling coating with non-selective spectral characteristics for indoor electronic devices. The MgO-stabilized ZrO₂/graphene (MSZ/G) powders are prepared in one step through combustion synthesis. Zirconium dioxide powders are utilized as a diluent in the combustion reaction of magnesium powders and carbon dioxide gas. The combustion process can reach a maximum temperature of 1869 °C. This study examines the impact of the diluent content on phase composition, microstructure, and absorptivity. The spectral absorptivity remains nearly constant, reaching up to 0.96, within the spectrum of 2.5–25 μm. The mechanism of absorption enhancement is illustrated in detail. The ZM8A-coated heat sink exhibits a decrease in equilibrium temperature of 9.1 °C when the heat power is 8 W. This outcome validates the effectiveness of non-selective broadband high-emissivity coatings for indoor thermal management. Therefore, this work provides simple and universal guidelines for designing radiative coating of electronic equipment that is not directly irradiated by solar.