Unraveling the Multifunctional Sites of Ag Single‐Atom and Nanoparticles Confined Within Carbon Nitride Nanotubes for Synergistic Photocatalytic Hydrogen Evolution

Abstract The development of novel nano‐single‐atom‐site catalysts with optimized electron configurations and active water adsorption ( * H 2 O) to release hydrogen protons ( * H) is paramount for photocatalytic hydrogen evolution (PHE), a multi‐step reaction process involving two electrons. In this study, an atom‐confinement and thermal reduction strategy is introduced to achieve synergistic Ag single‐atoms (Ag 1 ) and nanoparticles (Ag NPs ) confined within carbon nitride nanotubes (Ag 1+NPs ‐CN) for enhanced photocatalytic hydrogen evolution. Mechanistic investigations reveal that H 2 O adsorption/dissociation predominantly occurs at Ag 1 sites, while Ag NPs sites notably facilitate H 2 release, indicating the synergistic effect between Ag 1 and Ag NPs in the H 2 evolution reaction. Furthermore, the effective confining of Ag species is beneficial for trapping electrons in highly active reaction regions, while the “electronic metal‐support interactions” (EMSIs) of Ag NPs and Ag 1 ‐C 2 N sites regulate the d ‐band centers and effectively optimize the adsorption/desorption of intermediates in photocatalytic hydrogen evolution, leading to enhanced H 2 production performance. This work demonstrates the potential of the construction of synergistic photocatalysts for efficient energy conversion and storage; Hydrogen production; Nanoparticles; Photocatalysis; Single atom; and Synergistic effect.