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

Abstract

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.