Stable, while Still Active? A DFT Study of Cu, Ag, and Au Single Atoms at the C 3 N 4 /TiO 2 Interface.

Hybrid DFT calculations are employed to compare the adsorption and stabilization of Cu, Ag, and Au atoms on graphitic C 3 N 4 and on the heterojunction formed by g- C 3 N 4 and TiO 2 . While Cu and Ag can be strongly chemisorbed in form of cations on g- C 3 N 4 , Au is only weakly physisorbed. On g- C 3 N 4 /TiO 2 , all coinage metal adatoms can be strongly chemisorbed, but, while Cu and Ag forms cations, Au form an Au - species. Ab Initio Molecular Dynamics simulations confirm that the metal adatoms on g-C 3 N 4 are highly mobile at room temperature, while they remain confined in the interfacial spacing between C 3 N 4 and TiO 2 on the heterojunction, being both stably bound and reachable for the reactants in a catalytic cycle. Doping g- C 3 N 4 /TiO 2 with metal single atoms permits thus to generate catalytic systems with tunable charge and chemical properties and improved stability with respect to bare C 3 N 4 . Moreover, the changes in the electronic structure of g- C 3 N 4 /TiO 2 induced by the presence of the metal single atoms are beneficial also for photocatalytic applications.