Botz A, Clausmeyer J, Öhl D, Tarnev T, Franzen D, Turek T, Schuhmann W. Local Activities of Hydroxide and Water Determine the Operation of Silver-Based Oxygen Depolarized Cathodes.
Angew Chem Int Ed Engl 2018;
57:12285-12289. [PMID:
30073732 DOI:
10.1002/anie.201807798]
[Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Indexed: 11/09/2022]
Abstract
Local ion activity changes in close proximity to the surface of an oxygen depolarized cathode (ODC) were measured by scanning electrochemical microscopy (SECM). While the operating ODC produces OH- ions and consumes O2 and H2 O through the electrocatalytic oxygen reduction reaction (ORR), local changes in the activity of OH- ions and H2 O are detected by means of a positioned Pt microelectrode serving as an SECM tip. Sensing at the Pt tip is based on the pH-dependent reduction of PtO and obviates the need for prior electrode modification steps. It can be used to evaluate the coordination numbers of OH- ions and H2 O, and the method was exploited as a novel approach of catalyst activity assessment. We show that the electrochemical reaction on highly active catalysts can have a drastic influence on the reaction environment.
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