Boosting the photoexcited charge collection and transportation via BiVO4/Fe-TiO2 NRs in Type-II heterojunction for efficient photoelectrochemical water splitting

Abstract

Photoexcited charge separation and their efficient transportation in bulk as well as in heterojunction based photocatalysts is a challenging issue. Therefore, seeding free BiVO4@Fe-TiO2 NRs heterojunction is developed to have molecular extrinsic defects via Fe doping in TiO2 nanorods (NRs) as a strategy in type-II heterojunctions for photoelectrochemical water splitting. Structural characterizations of BiVO4@Fe-TiO2 NRs confirm the introduction of extrinsic defects in doped Fe-TiO2 NRs. Morphological studies evaluate the homogeneous deposition of BiVO4@Fe-TiO2 NRs to form core–shell heterostructure. In photoelectrochemical studies, BiVO4@0.2 %Fe-TiO2 shows highest photocurrent density of 1.52 mA/cm2 in comparison to BiVO4@undoped TiO2 NRs with 0.52 mA/cm2 and pristine TiO2 NRs with 45μA/cm2 at 1.23 vs. RHE under 100 mW/cm2 light intensity. These findings elucidate the importance of modified host substrates of Fe-TiO2 NRs to extract photoexcited electrons from guest BiVO4 that has enhanced PEC performance with maximum electron mobility, efficient interfacial charge transfer and enhanced electron quenching window in type-II heterojunctions.