title: Using cavity microelectrodes for electrochemical noise studies of oxygen-evolving catalysts.
abstract: Cavity microelectrodes were used as a binder-free platform to evaluate oxygen evolution reaction (OER) electrocatalysts with respect to gas bubble formation and departure. Electrochemical noise measurements were performed by using RuO2 as a benchmark catalyst and the perovskite La0.58 Sr0.4 Fe0.8 Co0.2 O3 as a non-noble metal OER catalyst with lower intrinsic conductivity. Changes in the current during the OER originate from variations in electrolyte resistance during the formation of the gas phase and partial coverage of the active area. Fluctuations observed in current and conductance transients were used to establish the contribution from the ohmic overpotential and to determine the characteristic frequency of oxygen evolution. The proposed quantitative determination of gas bubble growth and departure opens up the route for a rational interface design by considering gas bubble growth and departure as a main contributing factor to the overall electrocatalytic activity at high current densities.
authors.affiliation: Analytical Chemistry-Center for Electrochemical Sciences (CES), Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum (Germany).
authors.forename: Rosalba A
authors.initials: RA
authors.lastname: Rincón
authors.forename: Alberto
authors.initials: A
authors.lastname: Battistel
authors.forename: Edgar
authors.initials: E
authors.lastname: Ventosa
authors.forename: Xingxing
authors.initials: X
authors.lastname: Chen
authors.forename: Michaela
authors.initials: M
authors.lastname: Nebel
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schuhmann
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry; D002384:Catalysis; D004553:Electric Conductivity; D004563:Electrochemistry / Q000295:instrumentation*; D008839:Microelectrodes; D010087:Oxides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D017975:Ruthenium Compounds / Q000737:chemistry; D014025:Titanium / Q000737:chemistry
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D017975:Ruthenium Compounds; C029017:ruthenium dioxide; C059910:perovskite; D014025:Titanium; D010100:Oxygen
keywords: cavity microelectrodes; electrochemistry; gas-evolving electrodes; oxygen; perovskite phases