Combustion structuring of 3D nano- and microspheres: Advances and prospects for catalysis and energy storage

This review explores the combustion-driven structuring of three-dimensional nano- and microspheres (N&MSs) composed of various inorganic materials, including metals, alloys, non-metals, and binary and complex metal oxides. The introduction provides an overview of key synthesis techniques for N&MSs, with a focus on three combustion-based methods: self-propagating high-temperature synthesis (SHS), solution combustion synthesis (SCS), and flame synthesis (FS). Section 2 examines the fundamental mechanisms governing microsphere formation and the thermodynamic and kinetic models influencing this process. Section 3 details combustion-based approaches for fabricating dense and hollow N&MSs via SHS, SCS, and FS, critically analyzing how reaction time, flame temperature, reaction medium, and the choice of reactants and solvents impact particle morphology and size. Section 4 highlights the applications of N&MSs in energy storage, catalysis, sensing, and drug delivery. Finally, Section 5 discusses the advantages and limitations of combustion synthesis for nano- and microsphere production, offering perspectives on future research directions in this rapidly evolving field.