Polydopamine-Coated Manganese Complex/Graphene Nanocomposite for Enhanced Electrocatalytic Activity Towards Oxygen Reduction

Abstract

Platinum electrodes are commonly used electrocatalysts for oxygen reduction reactions (ORR) in fuel cells. However, this material is not economical due to its high cost and scarcity. We prepared an Mn(III) catalyst supported on graphene and further coated with polydopamine, resulting in superior ORR activity compared to the uncoated PDA structures. During ORR, a peak potential at 0.433 V was recorded, which is a significant shift compared to the uncoated material’s −0.303 V (both versus SHE). All the materials reduced oxygen in a wide pH range via a four-electron pathway. Rotating disk electrode and rotating ring disk electrode studies of the polydopamine-coated material revealed ORR occurring via 4.14 and 4.00 electrons, respectively. A rate constant of 6.33 × 106 mol−1s−1 was observed for the polydopamine-coated material–over 4.5 times greater than the uncoated nanocomposite and superior to those reported for similar carbon-supported metal catalysts. Simply integrating an inexpensive bioinspired polymer coating onto the Mn-graphene nanocomposite increased ORR performance significantly, with a peak potential shift of over +730 mV. This indicates that the material can reduce oxygen at a higher rate but with lower energy usage, revealing its excellent potential as an ORR electrocatalyst in fuel cells.

Chitosan‐Derived NiO‐Mn2O3/C Nanocomposites as Non‐Precious Catalysts for Enhanced Oxygen Reduction Reaction

“…Carbonaceous materials are very useful as catalyst supports and for improving the catalytic activity of many active electrocatalysts. Glassy carbon, carbon nanotubes, and graphene have been used as carbon materials for many years . The use of low‐cost carbon substrates such as activated carbon and biochar has been practiced to develop ORR catalysts ,.…”

Polydopamine – its Prolific Use as Catalyst and Support Material

“…Excellent activities were demonstrated with a nanocomposite of graphene with macrocyclic Mn 3+ complex 16 coated with PDA in electrocatalytic oxygen reduction . It showed a high peak potential of 0.433 V shifting from −0.303 V compared to the uncoated material.…”

Polydopamine-coated graphene nanosheets as efficient electrocatalysts for oxygen reduction reaction

“…The defects change the charge density, resistance in charge transfer, and hydrophilicity of the composite, which may increase its electrical conductivity and interaction with oxygen. 48 Moreover, the various types of Ncontaining functional groups will provide more active sites for ORR. 2,49 To further research the oxygen reduction process occurred on G-PDA-1, LSV measurements were carried out at various rotation speeds in O 2 -saturated 0.1 M KOH solution.…”