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Synergistic Effect of Tungsten Carbide and Palladium on Graphene for Promoted Ethanol Electrooxidation
journal contribution
posted on 2013-07-24, 00:00 authored by Jun Yang, Ying Xie, Ruihong Wang, Baojiang Jiang, Chungui Tian, Guang Mu, Jie Yin, Bo Wang, Honggang FuThe synergistic effect of WC and Pd has large benefit
for ethanol electrooxidation. The small-sized Pd nanoparticles (NPs)
decorated tungsten carbide on graphene (Pd-WC/GN) will be a promising
anode catalyst for the direct ethanol fuel cells. The density functional
theory (DFT) calculations reveal that the strong interaction exists
at the interface between Pd and WC, which induces the electron transfer
from WC to Pd. Fortunately, the nanoscale architecture of Pd-WC/GN
has been successfully fabricated in our experiments. X-ray photoelectron
spectrum further confirms the existence of electron transfer from
WC to Pd in a Pd-WC/GN nanohybrid. Notably, electrochemical tests
show that the Pd-WC/GN catalyst exhibits low onset potential, a large
electrochemical surface area, high activity, and stability for ethanol
electrooxidation in alkaline solution compared with Pd/graphene and
Pd/commercial Vulcan 72R carbon catalysts. The enhancement can be
attributed to the synergistic effect of Pd and WC on graphene. At
the interface between Pd and WC, the electron transfer from WC to
Pd leads to the increased electron densities of surface Pd, which
is available for weakening adsorption of intermediate oxygen-containing
species such as CO and activating catalyst. Meanwhile, the increased
tungsten oxide induced by electron transfer can facilitate the effective
removal of intermediate species adsorbed on the Pd surface through
a bifunctional mechanism or hydrogen spillover effect.