Cu-bridged polyoxovanadate coordination polymers assembled by distinct N-heterocyclic ligands for efficient photocatalytic hydrogen evolution.

The global energy crisis has made photocatalytic hydrogen production an ideal solution for sustainable energy development. Here, we report three novel Cu-bridged polyoxovanadates, {CuI2[1,4-bis(imidazol-1-ylmethyl)benzene]}{CuI2[1,4-bis(imidazol-1-ylmethyl)benzene]2}[V4O12] (1), {Cu[1,3-bis(4-pyridyl)propane](H2O)}[V2O6]·0.5H2O (2), and [Cu(2,2':6',2″-terpyridine)][V2O6] (3) [bix = 1,4-bis(imidazol-1-ylmethyl)benzene and bpp = 1,3-bis(4-pyridyl)propane, tpy = 2,2':6',2″-terpyridine], constructed through hydrothermal synthesis. A systematic research was carried out to elucidate structural features and relevant photocatalytic conversion processes. The diverse structural topologies of these target compounds are determined by single-crystal X-ray diffraction measurements. Compound 1 is a two-dimensional layered coordination polymer based on two distinct Cu+ coordination geometries. Compound 2 is a three-dimensional V-Cu hybrid framework built from one-dimensional vanadium-oxygen chains cross-linked by Cu2+ and pillared by bpp ligands. Compound 3 presents an infinite one-dimensional chain structure. In the tunable light-induced hydrogen evolution system, compound 2 displays superior catalytic activity. Under the optimized conditions, it achieves a hydrogen evolution rate of up to 4799.9 μmol g-1 h-1 and maintains stable catalytic activity over four consecutive cycles, demonstrating its promising potential for photocatalytic applications.