Efficient WO₃ Photoanode Modified by Pt Layer and Plasmonic Ag for Enhanced Charge Separation and Transfer To Promote Photoelectrochemical Performances

Effective separation and transfer of photogenerated charge as well as sufficient visible light harvesting play a crucial role on the photoelectrochemical performance of photoelectrodes. Hence, in this work, the WO₃ photoanode modified by plasmonic Ag nanoparticles (surface) and Pt nanoparticles (bottom) was designed and fabricated for the first time to realize efficient water splitting. In this Pt/WO₃/Ag photoanode, the Ag nanoparticles as photosensitizers enlarge the absorption spectrum and facilitate charge separation due to its fascinating SPR effect; moreover, the Pt layer serves as an electron collector to trap the electrons and then transfer them to the FTO substrate, where their synergistic effect leads to efficient charge separation and transfer. As a result, the Pt/WO₃/Ag photoanode yields an enhanced photocurrent of 1.13 mA/cm² at 1.23 V vs RHE under AM 1.5G illumination in a 0.2 M Na₂SO₄ solution, which is nearly 3.32 times that of bare WO₃. Furthermore, a hole transfer Co-Pi layer was introduced to further accelerate charge separation and transfer and improve the stability of the photoanode simultaneously, reaching a photocurrent density of 1.39 mA/cm² at 1.23 V vs RHE. This rational combination of noble metal nanostructures with semiconductors could provide a promising concept to design photoelectrodes efficiently in PEC water splitting.