Photocatalytic Water Oxidation by Surface Modification of BiVO₄ with Heterometallic Polyphthalocyanine

Developing efficient photocatalysts for water oxidationis amongthe central challenges of solar energy conversion. Here, we reportsemiconductor-molecular photocatalysts by integration of heteronuclearbimetallic polyphthalocyanine (PPc) catalysts with particulate bismuthvanadate (BiVO4) as the photosensitizer. Their photocatalyticactivity for water oxidation was modulated by tuning the Fe/Co ratioof polyphthalocyanines. At an optimal Fe/Co ratio of 3:1, the resultingFe(3)CoPPc-BiVO4 hybrid exhibits an excellentoxygen evolution rate of 4557 mu mol g(-1) h(-1) in the presence of iodate under visible light irradiation,which is nearly two orders of magnitude greater than that of pristineBiVO(4) and superior to those of the corresponding homometalliccounterparts. Both experimental and theoretical methods suggest thatthe presence of a large population of high-valent Fe/Co molecularspecies due to the favorable interfacial charge transfer and upshiftof the d-band centers of metal sites toward Fermi level lead to alower energy barrier for the O-O bond formation and eventuallypromote the oxidation of water.