Improvement of the Photocatalytic Water Splitting Activity of Silver Tantalate by Photodeposited Platinum and Cobalt-Oxide Nanoclusters

Abstract

In this paper, we studied platinum (Pt)-and cobalt oxide (CoO x )-loaded silver tantalate (AgTaO 3 ) for photocatalytic overall water splitting. Pt and CoO x were loaded on AgTaO 3 by photodeposition, and the obtained photocatalysts were characterized by using powder X-ray diffraction (XRD), UV-visible (UV-vis) absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and microscope inspection. By the scanning transmission electron microscope (STEM) inspection, the diameters of Pt and CoO x particles were found to be approximately 30 and 50 nm, respectively. When AgTaO 3 photocatalyst loaded with Pt and CoO x nanoparticles was employed for water splitting, the activity was demonstrated to be 80 times higher compared with the bare AgTaO 3 , indicating that the photodeposited Pt and CoO x effectively functioned as the hydrogen (H 2 ) and oxygen (O 2 ) evolution cocatalysts, respectively. While the use of photodeposited CoO x is often limited in photoelectrochemical water oxidation and photocatalytic half-reaction of water, CoO x deposited on AgTaO 3 could be demonstrated to enhance the photocatalytic overall water splitting activity.

Nanostructured materials for photocatalysis

“…84 To conclude, tantalate perovskites have received considerable focus compared to titanate and niobate active oxides due to the appropriate requisite conduction band edge (consisting of Ta 5d orbitals) for the generation of solar fuels. [85][86][87] However, the compounds of above mentioned ABO3 types are active under UV light and Silver Niobate (AgNbO3) (2.8 eV) has drawn some attention in photocatalysis due to its visible light response. 88 Such perovskite structured photocatalysts are composed of Ag 4d orbitals, far below the oxidation potential of water and therefore employed to split water under visible light in the presence of sacrificial agents.…”

Photodeposition of earth-abundant cocatalysts in photocatalytic water splitting: Methods, functions, and mechanisms

“…They found that the overall water splitting reaction to H2 and O2 was realized by photodepositing Co-Pi as the oxidation catalyst and Pt as the reduction cocatalyst on an yttrium-doped BiVO4. Irie et al [164] reported that the overall water splitting activity of silver tantalate (AgTaO3) increased by 80 times when Pt and CoOx nanoparticles were photodeposited on the surface functioning as the H2 and O2 evolution cocatalysts, respectively. Further work [165] showed that the photodeposition of Pt and Co-Pi cocatalysts can also promote photocatalytic water splitting into H2 and O2 with a stoichiometric ratio over niobium-substituted AgTaO3.…”