Ni doped amorphous FeOOH layer as ultrafast hole transfer channel for enhanced PEC performance of BiVO₄

Bismuth vanadate (BiVO₄), as the potential and prospective photocatalyst, has been limited by the issue of poor separation and transfer of charge carrier for photoelectrocatalytic (PEC) water oxidation. Here, a significant increase of surface injection efficiency for BiVO₄ is realized by the rationally designed Ni doped FeOOH (Ni:FeOOH) layer growing on BiVO₄ photoanode (Ni:FeOOH/BiVO₄), in which doped Ni²⁺ can induce partial-charge of FeOOH to serve as ultrafast transfer channel for hole transfer and transportation at the semiconductor/electrolyte interface. In addition, the Ni:FeOOH/BiVO₄ shows the η_surface value of 81.6 %, which is 3.28-fold and 1.47-fold of BiVO₄ and FeOOH/BiVO₄, respectively. The photocurrent density of Ni:FeOOH/BiVO₄ is 4.21 mA cm^-2 at 1.23 V vs. RHE, with the onset potential cathodically shifting 237 mV over BiVO₄ and a long-term stability for suppressing surface charge recombination. The UPS and UV-Vis spectra have confirmed the type-II band alignment between Ni:FeOOH and BiVO₄ for promoting carrier transfer. This facile and effective spin-coating method could deposit oxygen evolution catalysts (OECs) availably onto photoanodes with enhanced PEC water splitting.