A rotating disk electrode study of the particle size effects of Pt for the hydrogen oxidation reaction

• Published in: Physical chemistry chemical physics : PCCP 2012-01, Vol.14 (7), p.2278-2285
• Main Authors: Sun, Yu, Dai, Yu, Liu, Yuwen, Chen, Shengli
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts; Chemistry; Colloidal state and disperse state; Dispersions; Electrochemistry; Exact sciences and technology; General and physical chemistry; Kinetics and mechanism of reactions; Nanoparticles; Nanostructure; Oxidation; Particle size; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Platinum; Surface chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c2cp22761d

By using a catalyst-lean thin-film RDE method, the fast kinetics of the hydrogen oxidation reaction (HOR) on highly dispersed Pt nanoparticle electrocatalysts can be determined, free from the interference of the mass transport of H 2 molecules in solution. Measurements with carbon-supported Pt nanoparticles of different sizes thus allow revealing the particle size effect of Pt for the HOR. It is shown that there is a negative particle size effect of Pt on the kinetics of HOR, i.e. , the exchange current density j 0 decreases with the increased dispersion ( i.e. decreased mean particle size). A maximum mass activity of Pt for the HOR is found at particle sizes of 33.5 nm. The observed particle size effect is interpreted in terms of the size dependent distribution of surface atoms on the facets and edges, which is implied by the voltammetric responses of Pt/C catalysts with differently sized Pt particles. The accompanied decrease in the HOR activity with the increase in the edge atom fraction suggests that the edge atoms on the surface of Pt nanoparticles are less active for the HOR than those on the facets. A negative particle size effect of Pt on the specific kinetics of hydrogen oxidation reaction has been revealed by using a catalyst-lean RDE method. A maximum Pt mass activity is found to occur at particle sizes of 33.5 nm.