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Yang J.,China University of Mining and Technology | Song Y.,China University of Mining and Technology | Varela H.,University of Sao Paulo | Varela H.,Ertl Center for Electrochemistry and Catalysis | And 5 more authors.
Electrochimica Acta | Year: 2013

The adsorption of poisonous species on the catalyst surface impacts electrocatalytic reactions to different extents and by distinct means. The impact of adsorbing anionic species on electrocatalytic reactions has generally been investigated in the non-oscillatory regime or, at most, with temporal oscillations. Here, we report on spatiotemporal pattern formation in the electro-oxidation of sulfide on a platinum disk perturbed with dissolved chloride. The spatiotemporal dynamics was followed simultaneously with an electrochemical workstation and a charge-coupled device (CCD) camera. Perturbing the system with chloride results in (a) enhancement of dynamic instabilities throughout the current-potential curve, including regions of both positive and negative slope; (b) emergence of several spatial patterns; and (c) decreasing the width of pulses with increasing [Cl-]. The results are interpreted in terms of surface poisoning by chloride adsorption. © 2013 Elsevier Ltd. All rights reserved.

Shin D.,Korea Advanced Institute of Science and Technology | Jeong B.,Korea Advanced Institute of Science and Technology | Mun B.S.,Ertl Center for Electrochemistry and Catalysis | Mun B.S.,Gwangju Institute of Science and Technology | And 6 more authors.
Journal of Physical Chemistry C | Year: 2013

Nitrogen-carbon (N-C) species is a potential electrocatalyst for oxygen reduction reaction (ORR) in electrochemical energy conversion cells, but its mechanistic origin of ORR on the N-C surface is still unclear. We show our facile approach to the synthesis of highly active Co-modified N-C catalyst and investigated the origin of ORR activity of electrospun N-C species by removing the metal with hydroxide carbon etching and acid metal leaching. Through the detailed investigation on the origin of ORR electrocatalysis for electrospun N-C nanofibers, we revealed that pyrrolic-N and highly graphitized carbon structure are mainly responsible for the enhanced ORR activity of metal-free N-C nanofiber and embedded Co metal got involved in the creation of the pyrrolic N site. © 2013 American Chemical Society.

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