Performance evaluation of Pd/TiO₂ and Pt/TiO₂ photocatalysts for hydrogen production from ethanol-water mixtures
by Zakiya H.N. Al-Azri; Vedran Jovic; Wan-Ting Chen; Dongxiao Sun-Waterhouse; James B. Metson; Geoffrey I.N. Waterhouse
International Journal of Nanotechnology (IJNT), Vol. 11, No. 5/6/7/8, 2014

Abstract: This study compares the photocatalytic activity of Pd/TiO₂ and Pt/TiO₂ photocatalysts (metal loadings 0.5 wt.% and 2 wt. %) for H₂ production from ethanol-water mixtures under UV excitation. Cationic Pd(II) and Pt(IV)/Pt(II) species were deposited on Degussa P25 TiO₂ (85% anatase, 15% rutile) via the deposition-precipitation with urea method. Subsequent H₂ treatment at 350°C reduced the adsorbed cationic species to predominantly Pd⁰ and Pt⁰, respectively. TEM analyses of the Pd/TiO₂ and Pt/TiO₂ photocatalysts revealed supported Pd and Pt nanoparticles of size <3 nm. XPS studies confirmed that the platinum was present primarily in metallic form, whereas palladium was present as both Pd⁰ and PdO or Pd(OH)₂. Photoluminescence measurements demonstrated that Pd and Pt nanoparticles suppress electron-hole pair recombination in TiO₂ by acting as electron acceptors. The Pt/TiO₂ and Pd/TiO₂ photocatalysts exhibited high activity and stability for H₂ production, with the optimum metal loadings being 0.5 wt. % for Pt (H₂ production rate = 41 mmol h⁻¹ g⁻¹) and 2 wt. % for Pd (H₂ production rate = 34 mmol h⁻¹ g⁻¹). Results confirm that the presence of zero valent Pd or Pt is critical for efficient H₂ production, and that both Pt/TiO₂ and Pd/TiO₂ photocatalysts are promising materials for solar H₂ production from biofuels.

Online publication date: Tue, 16-Dec-2014

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