Integrating Polyoxometalates and Silver Clusters into Atomically Precise Molecular Heterojunction

The Ag cluster-POM assemblies have been shown to possess interesting and potentially useful properties. However, there is no precedent example of atomically precise Ag cluster-POM assemblies showing heterojunction effects in photocatalysis. Herein, the synthesis and total structure determination of the periodically distributed molecular heterojunction [Ag12(SCy)6(CH3CN)12(PW12O40)]n (Ag12-PW12) are reported. The assembly of Ag/W clusters into 3D network can endow the resulting binary structure with an aesthetic topology and unique physicochemical properties. More remarkably, the incorporation of Ag12 cluster with PW12 can efficiently facilitate the separation of photogenerated electrons and holes, thus significantly promoting the catalytic efficiency in selective oxidation of sulfides. The Ag12-PW12 heterojunction can be recovered and reused five times with no drastic change in the catalytic performance. This research is expected to assist in the rational design of cluster-based heterojunction catalysts. The increase of catalytic activity of the Ag12-PW12 assembly in comparison with the unassembled Ag12 and PW12 clusters is attributed to the synergistic effect of Ag12 and PW12 clusters, offering the splendid opportunity for deciphering structure-reactivity relationship of heterostructure-coupled photosystem. In the coordinated intercluster heterojunction, the directly bonding between cluster units result in interactive electronic structures of Ag12 and PW12 clusters, and reduction and oxidation reactions can take place simultaneously on these two clusters. These features contribute to enhancement in separation efficiency of photogenerated electron-hole, thereby causing improved O2<middle dot>- production efficiency and photocatalytic performance in oxidation of sulfides. image