Surface engineering of metallic nanocrystals via atomic structure and composition control for boosting electrocatalysis

Since the clean energy industry emerged, developing efficient nanocrystal catalysts has attracted ever-increasing attention. Recently, the utilization of metal nanocrystals as catalysts for electrochemical reactions is entering a new era with the development of theories and techniques that help incorporate surface chemistry into nanoscale materials. Current approaches in the field of nanocrystal catalysts include detailed analyses and modifications of the surface atoms of nanocrystals, with which optimal structures and compositions for target electrochemical reactions could be realized. This review presents two major strategies to engineer the surface structure of nanocrystals: control over the atomic arrangement and composition of nanocrystal surfaces. The first section mainly covers the modification of surface atom arrangements with various methods, including the induction of various facets, strains, and defects. The generation of anomalous crystal structures of nanocrystals is also discussed. The second section encompasses recent advances in controlling the composition of nanocrystal surfaces by bringing high entropy or periodicity to the metal elements in nanocrystals to attain high electrocatalytic activity and stability.