Photocurrent generation from thin films of ruthenium metallopolymer: polyoxometalate adducts using visible excitation

Thin layers of an electrostatically associated adduct formed between the polyoxomolybdate, [S2Mo18O62]4−, and the metallopolymers [Ru(bpy)2(PVP)10]2+ or [Ru(bpy)2(CO-P PIC)7]2+ have been deposited onto electrodes using alternate immersion layer-by-layer assembly; PVP is poly(4-vinylpyridine), bpy is 2,2ʹ′-bipyridyl, CO-P is poly[(4-(aminomethyl)styrene)1 (4-vinylpyridine)6] and PIC is 2-(4-carboxyphenyl) imidazo [4,5-f][1,10] phenanthroline. Raman spectroscopy reveals that the Ru-PVP:POM films exhibit an additional vibrational mode at 900 cm− 1 that is not present in either of the components suggesting significant electronic communication between the ruthenium centres and the polyoxomolybdate. Despite the similarity of their redox and photonic properties, this optical transition is absent in the Ru-Co-P:POM layers. Significantly, the Ru-PVP:POM films generate a higher photocurrent (38 ± 1 nA cm− 2) than the Ru-Co-P:POM films (8.9 ± 0.8 nA cm− 2) or [S2Mo18O62]4− films (9.7 ± 1.1 nA cm− 2) under visible irradiation.

Research Highlights
► Metallopolymer-polyoxometallate films photocatalytically oxidise benzyl alcohol.
► Photocurrent intensity depends on new optical transition observed in Raman.
► Subtle changes in metallopolymer structure significantly affects photocurrent.