5-Year advances in semisacrificial metal foam-derived materials for energy storage and electrocatalysis

3D metal foams have recently been developed as promising scaffolds for the fabrication of high-performance functional materials. Nevertheless, typical templating or coating methods usually face difficulties, such as poor adhesion at the interface and complicated fabrication procedures, which are detrimental to their practical applications. Recently, the development of semisacrificial conversion strategies for the direct transformation of the conductive substrate to a binder-free hierarchical architecture has received much attention due to their easy implementation and scalability. Despite the great progress achieved in this field, there is still a lack of a cohesive perspective that connects material design, conversion mechanism, and the corresponding application performance. Herein, an insightful overview is provided to correlate the key parameters of material design and conversion processes with structure-property-performance relationships. First, the main material design considerations are highlighted, and the roles played by various substrate properties, electrolyte composition and reaction conditions during the formation of hierarchical structures are illustrated. Next, the fundamental mechanisms of conversion reactions, including corrosion-induced dissolution, ion diffusion, nucleation kinetics and phase transition, are comprehensively reviewed, with emphasis on recent in situ or operando research results. Then, the relationships between the structural properties and the above mechanisms are elaborated in detail, thereby providing insights into their influence on electrochemical and catalytic properties. Moreover, a comparison with conventional synthesis strategies sheds light on the strengths and weaknesses of the semisacrificial strategies with respect to scalability, cost and functionalization efficiency. Lastly, the remaining challenges concerning structural homogeneity, unclear reaction mechanisms, and low stability are also summarized, together with future directions for developing advanced materials by applying AI-based design, characterization methods and sustainable synthetic strategies.