title: 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 × 10(6) mol(-1)s(-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.
authors.affiliation: Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204, USA.
authors.forename: Charlette M
authors.initials: CM
authors.lastname: Parnell
authors.affiliation: Department of Chemistry, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204, USA.
authors.forename: Bijay
authors.initials: B
authors.lastname: Chhetri
authors.affiliation: Department of Chemistry, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Brandt
authors.affiliation: Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204, USA.
authors.forename: Fumiya
authors.initials: F
authors.lastname: Watanabe
authors.affiliation: Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204, USA.
authors.forename: Zeid A
authors.initials: ZA
authors.lastname: Nima
authors.affiliation: US Food and Drug Administration, Office of Regulatory Affairs, Arkansas Regional Laboratory, 3900 NCTR Road, Jefferson, Arkansas 72079, USA.
authors.forename: Thilak K
authors.initials: TK
authors.lastname: Mudalige
authors.affiliation: Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204, USA.
authors.forename: Alexandru S
authors.initials: AS
authors.lastname: Biris
authors.affiliation: Department of Chemistry, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204, USA.
authors.forename: Anindya
authors.initials: A
authors.lastname: Ghosh