Bismuth nanostructures: catalytic pathways to sustainable technologies

• Systematic classification of Bi nanostructures with operando insights into dynamic catalytic surfaces. • Performance-driven design using defects, morphology, strain, and advanced heterostructures. • Unified structure–property–performance links between active sites and catalytic metrics. • Green, scalable, ML-accelerated synthesis of reactor-ready bismuth catalysts. Bismuth (Bi)-based nanostructures have emerged as pivotal candidates for sustainable energy conversion and environmental remediation due to their unique electronic configurations, semimetal to semiconductor transitions and earth abundance. However, translating laboratory into practical technologies is currently hindered by a fragmented understanding of dynamic active sites and the lack of a unified structure-performance framework. To bridge this gap, this review provides a comprehensive synthesis of the state of the art, which classifies the full spectrum of Bi-based nanostructures, including metallic Bi, oxides, oxyhalides, chalcogenides and perovskites. The novelty of this review is the integration of advanced operando and multimodal characterization analysis, which resolves the revolution of the dynamic surfaces under bias and light. We examine performance-centric design principles that couple strain and defect engineering with compositional tuning and rational heterostructure construction. These strategies are critically assessed across applications such as CO 2 reduction, hydrogen evolution, nitrogen fixation, and organic pollution degradation, explicitly linking active site motifs to kinetic descriptors. Furthermore, we outline scalable, green synthesis pathways and highlight the often overlooked but accelerating role of machine learning for discovery and uncertainty-aware benchmarking. Collectively, this work establishes a coherent roadmap for the rational design of next-generation catalysts, identifying decisive experience needed to translate fundamental advances into sustainable industrial technologies.