Gold based electro catalysts

Abstract

Gold electrocatalysts have been of growing interest in recent years owing to their reactivity for a variety of important reactions such as the oxygen reduction reaction. This activity has been shown to be dependent on the size of the supported electrocatalyst nanoparticles. In this thesis the effects of Au nanoparticle size are explored for the oxygen reduction, ethanol oxidation and carbon monoxide oxidation reactions (Chapter four). The results show the oxygen reduction and ethanol oxidation reactions were favoured using larger particles, 6 nm in diameter, whilst the CO oxidation reaction was more facile on smaller particles, 3 nm in diameter. The effects of size are attributed to the size dependent strength of the Au-O (H) bond. Modified Au nanoparticles, in which the Au serves as a core for a Pt or Pd shell have also been of recent interest, as Au has been less expensive than Pt. These core-shell electrocatalysts thus affect both cost and activity advantages as the underlying Au core affect the properties of the shell. In this thesis the effects of the particle size of the Au core on the activity of Pt or Pd shells have been investigated (Chapter five). The results show that the oxygen reduction reaction is well again more facile when the core size is larger, whilst the ethanol oxidation reaction now is favoured with the small Au core size. The coverage of Pt or Pd on the Au core was also found to be dependent on the particle size, with smaller particles being covered by thinner shells. Thus, the size dependence of the oxygen reduction activity is once again attributed to O (H) coverage and bond strength, whilst the ethanol oxidation is attributed to either an electronic perturbation of the Pt or Pd by the Au core of an ensemble effect

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ORCID for Andrea E. Russell: orcid.org/0000-0002-8382-6443

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