(678b) Density Functional Theory Study of Fepc Functionalized Graphene: A Potential Non-Precious Pt-Free Cathode Catalyst for Fuel Cell

Density Functional Theory Study of FePc Functionalized
Graphene: A Potential Non-precious Pt-free Cathode Catalyst for Fuel Cell

Sean Mussel and Pabitra Choudhury

Department
of Chemical Engineering, New Mexico Tech, Socorro, NM

Abstract

Fuel cells offer a
high potential for commercial and industrial use, however, severe shortcomings
of current technology, which needs to be overcome to make them economically
enticing at low temperature.  One of the main cost prohibitive features of fuel
cells is the use of large amount of platinum catalysts on both electrodes. One
of the most important barriers for complete fuel cell reactions is related to
the slow rate of cathode reaction where O₂ is reduced, known as
oxygen reduction reaction (ORR).  In spite of Pt catalyst is being used on the
cathode electrode, the kinetics is much slower than that of anode reaction. 
Recently, non-precious metal catalysts make replacement of Pt in ORR
electrocatalysts with earth-abundant elements such as Fe, Co, N and C have also
been realized.  As such, there is also an interest in reducing the amount of
PGM in the cathode catalysts.  However, over potential associated with the ORR
reaction on cathode catalysts is also one of the major concerns.  Our
hypothesis is that nonprecious single metal atom based catalyst center will not
only reduce both cost & energy barrier for ORR reaction but also reduce the
over potential associated with cathode catalysts. So, single metal atom based
catalyst center such as metal phthalocyanine has been tested on a graphene
substrate for ORR.  In this study, we have used first principles density functional theory (DFT)
calculations to study the structural, energetics and catalytic ORR reaction on
Iron-phthalocyanine (FePc) and Copper-phthalocyanine (CuPc) functionalized graphene.  The fundamental reaction mechanisms, how the non-precious single metal atom
based catalyst and/or support affects the ORR rate at the electronic structure
level will be discussed.  Finally, we
will also discussed the role of the central metal atom, ligand and several
single bridging atoms for tunable catalytic properties during ORR on the
cathode electrode. 

Acknowledgement:

DFT
calculation work was also supported from NSF TeraGrid (XSEDE) resources under
allocation number [TG-DMR140131]. Use of the Center for Nanoscale Materials was
supported by the US Department of Energy, Office of Science, Office of Basic
Energy Sciences, under Contract No. DE-AC02-06CH11357.