A comprehensive review on multi-functional Al2O3 nanocomposites: synthesis, properties and emerging applications in heat transfer, environmental remediation and biomedical systems

Abstract

Aluminium oxide (Al2O3) nanocomposites are increasingly emerging in modern engineering. However, there is still a significant gap in understanding how nanoarchitectonic design can be systematically combined with performance measures across different fields. The number of studies has examined individual functionalities; there is still a lack of a clear and integrated framework that connects synthesis strategies with the optimization of material properties for applications in heat transfer, environmental remediation and biomedical systems. This review brings together recent advances by examining how processing methods influence structural development and in turn, affect interfacial interactions and material performance. We examine how different fabrication methods, including sol–gel, hydrothermal synthesis, and emerging cold sintering techniques, influence key material characteristics such as phase composition (α- and γ-Al2O3), dispersion stability and thermal resistance at interfaces. The analysis shows that the shift from simply improving mechanical strength to achieving multifunctional performance depends largely on how the Al2O3 phase is carefully distributed and integrated within the host matrix. The findings also highlight the important role of interface engineering in improving thermal conductivity in nanofluids, accelerating adsorption during wastewater treatment and enhancing controlled bioactivity in drug delivery systems. We also examine the key challenges in moving these materials toward practical applications, particularly nanoparticle agglomeration and potential toxicity. The review further emphasizes the need for cradle-to-gate life-cycle assessments (LCA) to determine whether proposed synthesis methods can genuinely be considered environmentally sustainable. By taking an integrated approach that connects processing, structure, properties and performance, this review highlights data-driven nanoarchitectonic and scalable in situ synthesis as two key priorities for future research. Overall, Al2O3 nanocomposites offer strong potential for developing more sustainable technologies. However, their successful application will depend on better control of interfacial properties, along with careful consideration of environmental safety and the development of standardized methods that can be reliably applied at an industrial scale.