jp7b01586_si_001.pdf (1.47 MB)
The Tunable and Highly Selective Reduction Products on Ag@Cu Bimetallic Catalysts Toward CO2 Electrochemical Reduction Reaction
journal contribution
posted on 2017-05-01, 00:00 authored by Zhiyuan Chang, Shengjuan Huo, Wei Zhang, Jianhui Fang, Hailiang WangBimetallic
electrocatalysts can improve the activity and selectivity
over their monometallic counterparts by tuning the structure, morphology,
and composition. However, there scarcely was a systematic model to
understand the structural effect relationship on CO2 electrochemical
reduction reaction, especially for a product tuning process by introduction
of a second metal to grow into outer layers. Herein, we report a structure-controlled
model of the growth process of Ag@Cu bimetallic nanoparticles that
are fabricated by a polyol method, that is, reducing mixtures of Ag+ and Cu2+ (excess amount) in ethylene glycol (reducing
agent) in the presence of polyvinylpyrrolidone.
Structural characterizations reveal that a series of Ag@Cu NPs are
tuned from the Ag core, Cu modified Ag, to the Cu outer shell by controlling
the heating time (0–25 min). Moreover, highly selective catalysts
with the tuning reduction products from carbon monoxide to hydrocarbons
can be realized. Different from the “dilution” effects
between Ag and Cu, the volcanic curve for carbon monoxide production
is detected for the introduction of Cu and the peak point is the Ag@Cu-7
electrocatalyst (heating time is 7 min). Similarly, interestingly,
when the Cu cladding layer continuously grows, the hydrocarbons are
not a simple proportional addition and optimized at Ag@Cu-20 (heating
time is 20 min). The geometric effects dominantly account for the
synergistic effect of CO product and control the surface activity
to hydrocarbons. This study serves as a good starting point to tune
the energetics of the intermediate binding to achieve even higher
selectivity and activity for core–shell structured catalysts.