A surprising substituent effect in corroles on the electrochemical activation of oxygen reduction

Abstract

Four β-pyrrole-substituted cobalt(iii) corroles were studied as electrocatalysts for the oxygen reduction reaction. The results disclose high dependence of the corrole's performance on its substituents, but once adsorbed on a high surface area carbon, this effect vanishes, resulting in a better catalytic performance than most well-defined molecular electrocatalysts for this reaction.

Control of Molecular Catalysts for Oxygen Reduction by Variation of pH and Functional Groups

“…To further improve ORR performance, for example either by achieving a 4e − pathway at pH 0 (i. e., shifting the pH switch to 0) or by obtaining greater durability, it is necessary to identify the parameter that controls the effect of the substituent functional groups on the active site. Electron‐withdrawing ability (greatest for CF 3 ‐Corrole , intermediate for the ortho ‐Corrole and lowest for the para ‐Corrole ) of the substituent groups is known to affect the bonding of metallocorroles, [29] which is important for the ORR pathway and the protonation of the N atoms in N−C macrocycles. Since the p K a values of the corrole's N atoms are directly related to the electron‐withdrawing ability of the substituent groups and N‐atom protonation, the correlation between the obtained ORR characteristics and the p K a values of the N atoms of the three corroles was studied using DFT calculations (Table 1).…”

Tracking intramolecular energy redistribution dynamics in aryl halides: the effect of halide mass

“…[1][2][3][4] When substituted benzenes became the subject of a spectroscopic study, [5][6][7][8] there was much confusion regarding the results, such as the inuence of substituents on reactivity and stability of the very wide range of organic species containing aromatic moieties. [9][10][11][12] Analysis of mono-substituted benzenes reveals that the inuence of a single group will be essential. 11,12 Monosubstituted benzenes are chosen for this study because of our prior knowledge of benzene's intramolecular energy redistribution, 13 and we can describe a series of molecules where the basic phenyl structure remains unchanged.…”

“…[9][10][11][12] Analysis of mono-substituted benzenes reveals that the inuence of a single group will be essential. 11,12 Monosubstituted benzenes are chosen for this study because of our prior knowledge of benzene's intramolecular energy redistribution, 13 and we can describe a series of molecules where the basic phenyl structure remains unchanged. According to our previous work, 13 isolated-molecule energy ow of benzene was described, so the vibrational energy redistribution observed in liquid aryl halides X-Ph (X ¼ F, Cl, Br, I; -Ph ¼ C 6 H 5 ) is entirely a consequence of intramolecular interactions.…”

Nature-inspired electrocatalysts and devices for energy conversion

“…199 In addition to the metal center of the brominated corrole, its ORR activity is suggested to depend on the support, since adsorption of metallocorroles on activated carbon or carbon nanotubes decreases the reaction overpotential. 191,[199][200][201] Further research is needed to fully comprehend this phenomenon.…”