Isomerism Governed Molecular Electrocatalysis

Abstract

N4-macrocyclic molecules such as metal phthalocyanines and metal porphyrins (MN4 electrocatalysts) have been vastly investigated as viable non-precious molecular electrocatalysts for a wide range of electrochemical applications due to their fast redox processes, chemical and thermal stabilities, and highly tuneable optoelectronic properties. The influence that the functionalization in the secondary sphere exerts on their electrocatalysis and electronic structure is well studied. However, the effect of positional isomerism of the functional group on activity is much less explored. This work focuses on the role of isomerism of the amino functional group in the electrocatalytic activity of regioisomers of amino-substituted cobalt phthalocyanine functionalized at the α- and β- positions on the N4 macrocycle of the molecule. The synthesized electrocatalysts were anchored onto CNT support and the same was confirmed by various spectroscopic characterization. These TACoPc/CNT composites were probed for their activity towards the oxidation of hydrazine since it is a commonly used liquid fuel alternative for hydrogen in fuel cells. The β-TACoPc isomer was found to be a better catalyst than α-TACoPc and exhibited better performance in Hydrazine-Oxygen fuel cell. However, the α-TACoPc fuel cell showed more durability.