Ordered Mesoporous Polyoxometalate-Organosilica Frameworks as Efficient Photocatalysts of the Hydrogen Evolution Reaction.

Polyoxometalate clusters have been recently established as promising nanomaterials for photocatalytic water splitting. Here, the synthesis is reported of mesoporous polymers composed of a 3D porous network of lacunary [XM11 O39 ]q- (XM11 ; X=P, Si; M=W, Mo) polyoxometalate units connected by ethano-bridged silsesquioxane linkers through a block copolymer-templated crosslinking polymerization of 1,2-bis(triethoxysilyl)ethane in acidic solution. The resulting materials feature an ordered mesostructured ethane-silica (MES) framework that hosts a high density of accessible polyoxometalate clusters, which allows for efficient catalytic reactions. XM11 /MES hybrid polymers have a relatively high activity for the hydrogen evolution reaction with remarkable cycle stability under UV/Vis light irradiation (λ>360 nm), without the need for co-catalysts or additional photosensitizers. It is also shown that the photocatalytic efficiency of these materials arises from the nanoscale pore structure, high surface area and chemical manipulation of the electronic band structure of constituting heteropolyoxo clusters.