摘要
Two isostructural cobalt containing polyoxometalate water oxidation catalysts, [Co 4 (H 2 O) 2 (α-PW 9 O 34 ) 2 ] 10- (Co 4 P 2 ) and [Co 4 (H 2 O) 2 (α-VW 9 O 34 ) 2 ] 10- (Co 4 V 2 ), exhibit large differences in their catalytic performance. The substitution of phosphorus centers in Co 4 P 2 with redox-active vanadium centers in Co 4 V 2 leads to electronic structure modifications. Evidence for the significance of the vanadium centers to catalysis, predicted by theory, was found from soft X-ray absorption (XAS) and resonant inelastic X-ray scattering (RIXS). The XAS and RIXS spectra determine the electronic structure of the cobalt and vanadium sites in the pre-reaction state of both Co 4 V 2 and Co 4 P 2 . High-energy resolution RIXS results reveal that Co 4 V 2 possesses a smaller ligand field within the tetra-cobalt core and a cobalt-to-vanadium charge transfer band. The differences in electronic structures offer insights into the enhanced catalysis of Co 4 V 2 .