Structure, stability and photocatalytic H2 production by Cr-, Mn-, Fe-, Co-, and Ni-substituted decaniobate clusters.

Here we report synthesis and characterization of early transition-metal(TM)-substituted decaniobates as a continuation of our previous report of tetramethylammonium (TMA) salt of FeNb9 and NiNb9: TMA6[H2Cr(III)Nb9O28]·14H2O (1, CrNb9), TMA8[Mn(III)Nb9O28]·29H2O (2, MnNb9) and TMA7[H2Co(II)Nb9O28]·25H2O (3, CoNb9). Among the TM-substituted decaniobates, CoNb9 or NiNb9 exhibit a higher photocatalytic H2 evolution activity in methanol-water mixtures than others.