Résumé
Combining two photocatalysts to form heterojunctions is a common strategy to enhance the photoelectrochemical (PEC) performance in water splitting. However, this approach requires suitable band alignment between the two photocatalysts, which limits its effectiveness or even deteriorate the performance, as seen with mismatched type I heterojunctions. In this work, we design a dual photoanode configuration overcoming the unfavorable type I band alignment commonly formed in TiO2/BiVO4 heterojunctions. Using pulsed laser deposition (PLD), we optimized the deposition parameters to independently maximize photocurrent generation in transparent TiO2 and BiVO4 films, deposited separately on FTO substrates. The two photoanodes were then connected and positioned back-to-back, with the TiO2 photoanode facing the light source and the BiVO4 photoanode illuminated by light passing through the TiO2 layer. The TiO2/BiVO4 dual photoanode generates a photocurrent of 1.72 mA/cm2 at 1.3 V vs. RHE, 2.3 times higher than that of TiO2/BiVO4 heterojunction. Similarly, PEC hydrogen production increased to 14.2 μmol cm 2 h 1, which is 2.25 times higher than BiVO4 alone and 2.9 times greater than TiO2/BiVO4 heterojunction. This improvement is attributed to the extended light absorption and larger active surface area provided by the dual photoanode, while avoiding the charge carrier recombination typically associated with type I heterojunction interfaces.