State‐of‐the‐Art in Co₃O₄ Nanoparticle Synthesis and Applications: Toward a Sustainable Future

Abstract Cobalt oxide nanoparticles (Co₃O₄ NPs) have emerged as highly versatile materials, recognized for their unique physicochemical properties, including superior thermal stability, magnetic characteristics, and exceptional catalytic activity. These properties have driven extensive research into their applications across diverse fields, such as environmental remediation, energy storage, and biomedical treatments. This review provides a comprehensive analysis of Co₃O₄ nanoparticle synthesis, focusing on both conventional physicochemical methods and advanced green synthesis approaches. Each synthesis method is critically assessed for its impact on particle morphology, size, and environmental compatibility, while addressing key challenges in achieving scalable and eco‐friendly production. The functional applications of Co₃O₄ NPs are explored in detail, particularly their roles in photocatalytic pollutant degradation, antibacterial applications, and energy devices, where their distinctive spinel structure is pivotal. This review consolidates recent advancements in the field and emphasizes the innovation potential of Co₃O₄ NPs as a sustainable material solution for next‐generation technologies.