Novel hierarchical ferric phosphate/bismuth vanadate nanocactus for highly efficient and stable solar water splitting

A three-dimensional branched array based on ferrite phosphate/bismuth vanadate has been was fabricated for photoelectrochemical water splitting. Such a unique architecture not only offer fast charge transport but also higher surface, thus in turn boosted the photoelectrocatalytic activity and photoanode stability. [Display omitted] •Unique fluffy nanocactus ferrite phosphate/bismuth vanadate is successfully fabricated.•The integrated photoanode exhibits superior water splitting properties.•Surface recombination of photogenrated electron-hole pairs is near-complete suppressed.•Deposition of cocatalyst is critical to stabilize bismuth vanadate durability. Severe surface charge recombination is known as a major energy loss that hinders the performance and durability of solar water splitting. Here, a facile process is developed for preparing a new type of low-cost ferrite phosphate as an efficient co-catalyst to suppress charge recombination and stabilize bismuth vanadate (BiVO4) photoelectrodes. The composite photoanode exhibits a high photocurrent density of 2.28 mAcm−2, which corresponds to a 250% increase compared to that of pristine BiVO4. Deposition of cocatalyst has yielded a large cathodic shift (∼500 mV) in the onset potential, high hole oxidation efficiency of about 90%. The Fe-Pi/ BiVO4 photoanode demonstrates an impressive performance of photostability and attains a stable photocurrent density for more than 2 h at 1.23 VRHE without declining. Comprehensive photoelectrochemical studies suggest that ferrite phosphate could boost the photoelectrochemical properties of the BiVO4 underlayer by mediating hole extraction across the photoexcited semiconductor-electrolyte interface. This in turn enhances photoconversion efficiency and prevents the photooxidation of the photoanode, ensuring prolonged stability. The results provide deeper understanding of the role of cocatalyst nanostructures decorated with semiconductors in solar water splitting.