Surface Interrogation of Electrodeposited MnOx and CaMnO3 Perovskites by Scanning Electrochemical Microscopy: Probing Active Sites and Kinetics for the Oxygen Evolution Reaction.

Surface Interrogation of Electrodeposited MnOx and CaMnO3 Perovskites by Scanning Electrochemical Microscopy: Probing Active Sites and Kinetics for the Oxygen Evolution Reaction. Angew Chem Int Ed Engl. 2020 Sep 16;: Authors: Jin Z, Bard AJ Abstract Here we report the surface interrogation scanning electrochemical microscopy (SI-SECM) of two electrodeposited manganese-based electrocatalysts, amorphous MnOx and perovskite CaMnO3, to investigate the manganese oxidation state relating to the oxygen evolution reaction (OER) under neutral conditions. The results indicate the amounts of Mn(III) and Mn(IV) species in MnOx and CaMnO3 depend on potential. A Mn(V) species was identified in both structures during the OER. Time-delay titration of Mn(V) further revealed that MnOx produced two types of active sites with different OER reactions rates, k'fast(MnOx) = 1.21 s-1 and k'slow(MnOx) = 0.24 s-1. In contrast, CaMnO3 perovskites in which the Mn(V) species formed at a less positive potential than that in MnOx, displayed only one kinetic behavior with a faster reaction rate of 1.72 s-1. PMID: 32939974 [PubMed - as supplied by publisher]
Source: Angewandte Chemie - Category: Chemistry Authors: Tags: Angew Chem Int Ed Engl Source Type: research