Synthesis and characterization of hybrid MgAl-LDH@SiO2@CoAl2O4 pigment with high NIR reflectance for sustainable energy saving applications

Abstract This paper reports a novel approach for the synthesis of MgAl-LDH, MgAl-LDH@SiO2, CoAl2O4, and MgAl-LDH@SiO2@CoAl2O4 in order to make a hybrid pigment. SEM, TEM, XRD, Raman spectroscopy, elemental mapping, TG/DTG, optical microscopy, UV–vis-NIR spectrophotometry, and CIE 1976 L*a*b* color coordinates were used to characterize the synthesized pigment compounds. The proposed approach enabled the preparation of a compound pigment consisting of at least 40 wt% CoAl2O4 without deteriorating color properties. The results also showed outstanding chromatic and NIR reflectance properties for MgAl-LDH@SiO2@CoAl2O4 (CoAl2O4 = 0.4 g; L* = 51.04, a* = −12.918, b* = −6.911, C* = 14.65, h angle = 208.14) and MgAl-LDH@CoAl2O4 (CoAl2O4 = 0.4 g; L* = 43.99, a* = −14.90, b* = −7.22, C* = 16.56, h angle = 205.84) pigments. Moreover, it was found that the higher the CoAl2O4 concentration, the higher is the NIR reflectance. The synthesized hybrid pigment not only provides better cooling effect and less energy consumption in exterior applications, but it can also reduce the need for procurement of expensive cool pigments.