Controllable Synthesis of Hollow Silica Nanoparticles Using Layered Double Hydroxide Templates and Application for Thermal Insulation Coating

The innovative hollowsilica nanoparticle (HSN) material possessessubstantial potential for application in the insulation field. Thesize and shell thickness of HSN are crucial factors in determiningtheir inherent properties, which, in turn, impact their applicability.This research presents a facile approach to synthesizing HSN in whichsodium silicate (Na2SiO3) was utilized as thesilica precursor that can be directly deposited onto layered doublehydroxide (LDH) nanoparticles without the utilization of any surfactant.A subsequent acid treatment was used to eliminate the templates, resultingin the formation of an HSN devoid of mesopores in silica shells. Byutilizing various sizes of LDH cores, obtainable via coprecipitationfollowed by hydrothermal treatment, we were capable of successfullysynthesizing the hollow particles with adjustable diameters rangingfrom 50 to 200 nm. In addition, the shell thickness is varied from6.8 to 22.5 nm by varying the silicate solution concentration. Resultsdemonstrate that prepared HSNs have low thermal conductivity and highreflectance in the UV-vis-NIR range (averaging 82.1%).These findings suggest that HSN can be utilized as an effective inorganicfiller in the formulation of reflective and thermally insulating coatings.