Cactus shaped FeOOH/Au/BiVO4 photoanodes for efficient photoelectrochemical water splitting

In this work, a FeOOH/Au/BiVO 4 photoanode was fabricated through dual modification with Au nanoparticles (NPs, ∼5 nm) and FeOOH nanoneedles (NNs) on nanoporous BiVO 4 surface. Both the Au NPs and FeOOH NNs were distributed uniformly onto the BiVO 4 by using the electrodeposition and chemisorption routes, respectively. After parameter optimization, the FeOOH/Au/BiVO 4 photoanode displayed a photocurrent density of 4.64 mA cm −2 at 1.23 V RHE , which was 3.74 times higher than the pristine BiVO 4 one. Besides, the FeOOH/Au/BiVO 4 photoanodes also displayed a maximum H 2 yield amount of 23.9 μmol cm −2 h −1 . The significantly enhanced performance could be attributed to the following reasons: Introduction of Au NPs enhanced the visible light absorption through localized surface plasmon resonance (LSPR) effect; the photo-excited “hot electrons” of Au NPs were more likely to flow into the conduction band (CB) of BiVO 4 via a direct electron transfer mechanism, leading to an improvement of the charge separation/transfer efficiency; surface modification of FeOOH extracted photogenerated holes, leading to an acceleration of the surface catalytic kinetics. In a word, the present study suggests that co-sensitization of Au NPs and FeOOH might be an effective method for improving the PEC water oxidation kinetics of BiVO 4 photoanodes. • FeOOH/Au/BiVO 4 photoanodes were fabricated through co-modification of Au NPs and FeOOH on porous BiVO 4 films. • Under a bias of 1.23 V RHE , FeOOH/Au/BiVO 4 displayed a photocurrent of 4.64 mA cm −2 , which was 3.74 times higher than BiVO 4 . • H 2 yield amount reaches 191.4 μmol in 2 h for the optimal FeOOH/Au/BiVO 4 photoanode. • Performance enhancement was attributed to improvements of both visible light harvesting and surface catalytic kinetics.