A dual-functional supramolecular assembly for enhanced photocatalytic hydrogen evolution

The construction of multifunctional supramolecular assembly is a central research interest in solar-driven water splitting to hydrogen. We here report the successful preparation of a dual-functional supramolecular assembly via facile electrostatic integration of a positively-charged Ir-based chromophore and a negatively-charged nickel-substituted polyoxometalate catalyst. The resulting dual-functional supramolecule can form ordered vesicle-like assemblies and work efficiently as both light-absorber and catalyst for hydrogen production under visible light irradiation. Under minimally optimized conditions, a catalytic hydrogen production turnover number of over 4000 was achieved after 96-hour irradiation, which is 17 times to that of discrete components under otherwise identical conditions. Destruction of such ordered vesicle-like assemblies will lead to a remarkable decrease of photocatalytic hydrogen production activity. Mechanistic studies further revealed the presence of both oxidative and reductive quenching processes during photocatalysis and also confirmed that the formation of ordered supramolecule is beneficial for effective electron transfer between chromophore and catalyst.