Improving the thermophysical aspects of innovative clay brick composites for sustainable development via TiO2 and rGO nanosheets

Abstract

In the current work, distinctive nanoscale fillers, such as reduced graphene oxide (rGO) and titanium oxide (TiO2), were synthesized to open up novel opportunities to enhance the thermal performance of clay brick composites. Innovative clay-based nanocomposite bricks with various doping levels, including untreated clay, clay–rGO, clay–TiO2 and clay–rGO–TiO2, were synthesized for the first time to enhance brick's thermophysical performance. Physical observations of microstructure, shrinkage, morphology, density, porosity, as well as thermophysical characteristics of the composite clay bricks were investigated. Incorporating a varying quantity of rGO and TiO2 nanoparticles (NPs) into the clay matrix resulted in a variation in peak intensity within the lattice structure, along with a rise in the estimated crystallite size to 30.3 nm of clay–rGO–TiO2 composites. Meanwhile, the wealthy hydroxyl groups of TiO2 and rGO NPs boost the formation of many hydrogen bonds well distributed within clay structures, leading to rigid filler adherence. Moreover, the apparent porosity rose (i.e. from 24.01% to 43.64%) due to the creation of new intermolecular covalent bonds and hydrogen bonds between clay–H2O and metal oxides–OH groups. This porosity results in lighter bricks (i.e. bulk density decomposes from 2.02 to 1.41 g/cm3) with a pore size on the order of 3.5 µm. These variations are supported by the differ-dense microstructure presented in the SEM images. Interestingly, the Clay–rGO–TiO2 mixture not only has a high thermal conductivity value (0.44 W/mK), but also exhibits exceptional thermal diffusivity (4.1 mm2/S). The existence of TiO2 NPs, along with rGO nanosheets with a large surface area and high porosity features, which efficiently permits liquid absorption of the interlayers is the main explanation for these findings.