Emerging Morphology-Controlled Microspheres for Next-Generation Functional Materials and Devices: From Formation Mechanisms to Applications.

Controlling hierarchical organization across multiple length scales is a central challenge in materials science. Microspherical architectures offer powerful platforms for addressing this challenge because their confined geometry enables the integration of nanoscale interfaces, internal porosity, and structural hierarchy within a single functional unit. These features have driven extensive exploration of microspheres for applications in biomedicine, catalysis, photonics, and energy systems. However, the mechanistic connections between microsphere formation pathways and emergent functionality remain fragmented, limiting predictive materials design. Here, we present a unified perspective on morphology-controlled microspheres by integrating thermodynamic principles, kinetic processes, and hierarchical materials design. We examine key formation mechanisms, including nucleation, growth dynamics, phase separation, Ostwald ripening, and interfacial energy regulation, and analyze how major fabrication strategies such as sol-gel processing, hydrothermal synthesis, spray assembly, emulsification, and co-precipitation govern nanoscale organization and structural evolution. By linking formation mechanisms with functional outcomes, this Review establishes general design principles and highlights emerging opportunities for predictive nanoarchitectonic engineering of microsphere-based functional materials.