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Single Atom Hot-Spots at Au-Pd Nanoalloys for Electrocatalytic H<sub>2</sub>O<sub>2</sub> Production

Artikel i vetenskaplig tidskrift
Författare Jakub S Jirkovský
Itai Panas
Elisabet Ahlberg
Matej Halasa
Simon Romani
David J. Schiffrin
Publicerad i Journal of the American Chemical Society
Volym 133
Nummer/häfte 48
Sidor 19432-19441
ISSN 0002-7863
Publiceringsår 2011
Publicerad vid Institutionen för kemi
Sidor 19432-19441
Språk en
Länkar dx.doi.org/10.1021/ja206477z
Ämneskategorier Elektrokemi, Kinetik, Kvantkemi, Annan kemiteknik

Sammanfattning

A novel strategy to direct the oxygen reduction reaction to preferentially produce H2O2 is formulated and evaluated. The approach combines the inertness of Au nano-particles towards oxidation, with the improved O2 sticking probability of isolated transition metal “guest” atoms embedded in the Au “host”. DFT modeling was employed to screen for the best alloy candidates. Modeling indicates that isolated alloying atoms of Pd, Pt or Rh placed within the Au surface should enhance the H2O2 production relative to pure Au. Consequently, Au1-xPdx nanoalloys with variable Pd content supported on Vulcan XC-72 were prepared to investigate the predicted selectivity towards H2O2 production for Au alloyed with Pd. It is demonstrated that increasing of Pd concentration to 8% leads to an increase of the electrocatalytic H2O2 production selectivity up to nearly 95%, when the nanoparticles are placed in an environment compatible with that of a proton exchange membrane. Further increase of Pd content leads to a drop of H2O2 selectivity, below 10% for x = 0.5. It is proposed that the enhancement in H2O2 selectivity is caused by the presence of individual surface Pd atoms surrounded by gold whereas surface ensembles of contiguous Pd atoms support H2O formation. The results are discussed in the context of exergonic electrocatalytic H2O2 synthesis in Polymer Electrolyte Fuel Cells for the simultaneous cogeneration of chemicals and electricity, the latter a credit to production costs.

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