Promoted photocatalytic hydrogen evolution via double-electron migration in Ag@g-C3N4 heterojunction.

The unsaturated edge Ag introduced on the surface of photocatalysts plays an important role in boosting photo-excited electrons for the photoreduction H 2 O reaction. However, a moderate and tractable strategy to efficiently expose edge Ag remains an enormous challenge. For this purpose, a core skeleton with 'Ag conductive nanosphere array' inside and a two-dimensional sheet structure with g-C 3 N 4 layer outside are formed. The introduction of Ag nanospheres into g-C 3 N 4 not only enlarges the distance between g-C 3 N 4 nanolayers, but also increases the exposure of Ag nanospheres. When Ag intimately contacts with g-C 3 N 4 , the electrons of g-C 3 N 4 voluntarily flow to the Ag. Consequently, a built-in electric field (IEF) has been formed at interface of Ag@g-C 3 N 4 heterojunction, which prevents the continuous flow of electrons from g-C 3 N 4 to Ag. Under irradiation, the e− accumulated in Ag tend to recombine with the h+ in the valence band of g-C 3 N 4 which is driven by Coulomb interaction and IEF. Ag nanospheres are fabricated as a co-catalyst to decorate the g-C 3 N 4 nanolayer, which hinder the conglomeration of g-C 3 N 4 nanolayers. Moreover, Ag@g-C 3 N 4 heterojunction provides polyunsaturated edge Ag as active sites, inducing prolonged lifetime of photogenerated electrons and formed the unique charge transfer channels. In addition, abundant nitrogen vacancies are formed, which strengthens the chemisorption of H 2 O. As a result, supreme Ag@g-C 3 N 4 realizes a high H 2 evolution of 312.5 μmol and preserves a good sustainability. This paper emphasizes the importance of unique electron transfer pathway and chemisorption of water for photoreduction H 2 O. [Display omitted] • Band structure of Ag@g-C 3 N 4 is conjectured by the experiments and DFT calculations. • Surface nitrogen vacancy and prolonged photocarrier lifetime has improved H 2 evolution. • Surface nitrogen vacancy is responsible for the chemisorption and activation of H 2 O. [ABSTRACT FROM AUTHOR]