A simplistic and
facile approach for the fabrication of Nafion-free
highly efficient oxygen reduction
reaction (ORR) electro-catalyst based on Pt3Co alloy nanoparticles
supported on carbon fiber paper (Pt3Co@CFP) via potentiostatic
electro-deposition method is presented. Besides being rapid and facile,
this method is highly effective and allows easy control over the kinetics
of nucleation and growth process as a function of electro-deposition
parameters. Here, we have optimized the electro-deposition time to
obtain the Pt3Co electro-catalyst loaded CFP as a Nafion-free
electrode that shows enhanced electro-catalytic activity for ORR after
fabricating Pt3Co@CFP electrode via electro-deposition
of Pt3Co on CFP for varying time intervals, viz. 5, 10,
15, and 20 min. The ORR electro-catalytic activity of Pt3Co electro-deposited for varying time intervals has been noted to
be a function of varying physicochemical features such as predominance
of (111) diffraction plane, ratio of Pt-oxide to metallic Pt, and
the size and morphology of the electro-deposits, which in turn can
be controlled by varying the electro-deposition time. The Pt3Co@CFP electro-catalyst obtained at electro-deposition time of 10
min exhibited the best ORR activity among others, following four electron
transfer pathways with minute peroxide formation. Moreover, the corresponding
electro-catalysis parameters for ORR, viz. onset potential of 0.85
V vs RHE at 1.0 mA cm–2 of current density, limiting
current density of 25.8 mA cm–2 at 2500 rpm and
0.2 V vs RHE, Tafel slope of 63 mV dec–1, intrinsic
current density of 40.44 mA cm–2, and 4.18 ×
10–3 cm s–1 are best compared
to the previously reported values for Pt3Co alloy based
electro-catalysts. Furthermore, we also studied the effect of Nafion
binder on the electro-catalytic activity toward ORR which suggests
that the Nafion binder lowers the ORR activity of the Pt3Co catalyst as indicated by lower specific current density and shifting
the peak potential to the higher potential.