Fabrication of a stable Au/Ta2O5 plasmonic photoanode for water splitting under visible light irradiation

Abstract

Many investigations have been carried out on the production of hydrogen (H₂) by water splitting using energy efficiently. We investigated photoelectrochemical water splitting (2H₂O → 2H₂ + O₂) using the surface plasmon resonance of gold (Au) nanoparticles, in which tantalum pentoxide (Ta₂O₅) was selected as the supporting material for Au. Au/Ta₂O₅ powder was prepared by using the deposition precipitation (DP) method and subsequent calcination, and an Au/Ta₂O₅ electrode having a Ta₂O₅ layer of ca. 3 μm in thickness and Au⁰ nanoparticles of 6.4 nm in average size was fabricated by using a squeegee method. The prepared powder and electrode were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. The Au/Ta₂O₅/FTO electrode was used as the working electrode and the current–potential curve was measured under visible light irradiation, which showed photoresponse of more than 0.5 V vs. RHE. H₂ and oxygen (O₂) were continuously produced under visible light irradiation and with an externally applied potential of 0.8 V vs. RHE to a Pt counter electrode. The results of this study will provide a new strategy for photoelectrochemical water splitting using a plasmonic photoanode.