A simple one-step synthetic route to access a range of metal-doped polyoxovanadate clusters

VO(O i Pr) 3 is a useful precursor for the synthesis of a range of metal-doped polyoxovanadate (POV) cage compounds, its reactions with hydrated metal salts providing a route to arrangements containing Bi and other main group metals, transition metals and lanthanides. The new POV compounds [Bi 2 (DMSO) 6 V 12 O 33 Br] 2 [M(DMSO) 6 ] ( 2 Br -M , M = Co II , Ni II , Cu II , Zn II ) [Bi 2 (DMSO) 6 V 12 O 33 Cl] 2 [Ca(DMSO) x ]· y DMSO ( 2 Cl -Ca ), [Bi 2 (DMSO) 6 V 12 O 33 Cl] 2 [LnCl(DMSO) 7 ] ( 2 Cl -Ln , Ln = La III , Ce III , Eu III ), [Bi 2 (DMSO) 6 V 10 O 28 F 2 ] 3 [Bi(DMSO) 5 ] 2 ( 3 ), [V 12 O 32 (DMSO)][Gd(NO 3 )(DMSO) 5.5 ] 2 ( 4 ) and [Ln(DMSO) 4 V 12 O 32 Cl][LnCl(DMSO) 7 ] ( 5 Cl -Ln , Ln = Ce III , Eu III ) have been structurally characterised, and their properties studied using UV-Vis spectroscopy and cyclic voltammetry. Drop-casting these compounds onto fluorine-doped tin oxide followed by calcination provides a simple approach to thin films of metal-doped BiVO 4 or LnVO 4 , depending on the composition of the cage precursor. The applications of the BiVO 4 films as photoanodes for water oxidation is explored, with transition metal doping of BiVO 4 improving the activity (∼1.8-2.4 times the photocurrent density of undoped BiVO 4 at 1.23 V vs. RHE) while lanthanide or Ca-doping is detrimental. A simple one-step synthetic route to access a range of metal-doped polyoxovanadate clusters.