Abstract
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•A highly conformal 10–15 nm layer of NiFe based Prussian blue co-catalyst is coated on BiVO4 electrodes.•The coating boosted the photocurrent of BiVO4 electrodes by 10-fold to 3.23 mA/cm2.•A low onset potential of 0.2 V and photo-corrosion inhibition for > 50 h are also achieved.
BiVO4 is one of the most promising semiconductors for photoelectrochemical water splitting. BiVO4 is, however, limited by poor charge separation and slow oxygen evolution dynamics, for which surface modification with oxygen evolution catalysts (OECs) becomes indispensable. Among many OECs, Prussian blue type coordination polymers have lately attracted an escalating research interest attributable to their low cost, chemical robustness and easy synthesis using nontoxic earth-abundant elements. In this study, we report a simple method for efficient surface modification of Zr-doped BiVO4 nanostructured electrodes with an amorphous Ni-Fe based Prussian blue (NiFePB) polymer. The method resulted in a remarkable 10-fold enhancement of photocurrent (3.23 mAcm−2 at 1.23 V versus the reversible hydrogen electrode RHE) and a low onset potential of 0.208 V versus RHE, which are both records for Prussian blue (PB) type materials. Our coating method results in a (Zr)BiVO4/NiFePB core-shell structure, in which a 10–15 nm NiFePB shell makes a superior conformal coating with complete coverage on the (Zr)BiVO4 nanoparticles. The high conformity and amorphous nature of the coating are believed to be key features for the high photocatalytic activity and for a high photocorrosion resistance of the photoanodes during > 50 h of AM1.5 G solar illumination. Our method illustrates the large potential of Prussian blue type materials, when properly coated, as efficient and highly stable OECs.