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Journal of Applied Electrochemistry (2018) 48:435–441
https://doi.org/10.1007/s10800-018-1166-6
RESEARCH ARTICLE
Electrochemical reduction of CO
2
at CuAu nanoparticles: size and alloy
effects
Evan Andrews
1
· Yuxin Fang
1
· John Flake
1
Received: 13 October 2017 / Accepted: 5 February 2018 / Published online: 19 February 2018
© Springer Science+Business Media B.V., part of Springer Nature 2018
Abstract
Reduction of CO
2
at Cu or Au electrodes typically yields methane or CO, respectively. Cu and Au nanoparticles and their
alloys offer unique advantages over foil electrodes in terms of reduced overpotentials and product selectivities. In this work,
we explore the electrochemical reduction of CO
2
in aqueous electrolytes using alloys of Cu and Au including 2 and 6 nm
nanoparticles along with polycrystalline foils. These results show the CuAu alloys primarily produce CO; however, yields
are dramatically increased relative to Au. CuAu electrodes in the form of planar foils produce up to 3.4 times more CO
yields relative to Au foil. Most remarkably, nanoparticle electrodes provide up to 12.5-fold CO yield increases relative to
polycrystalline alloy foils and 175-fold CO yield increases relative to bulk Au foils. Voltammetry shows that onset potentials
for CO
2
reduction are shifted anodically with smaller nanoparticle sizes and with greater Au content. The dramatic increase
in CO yields with nanoparticle alloys is attributed to the improved CO
2
deoxygenation associated with Cu interfaces and
the relatively facile desorption of CO from low-coordination Au sites.
Graphical Abstract
O=C=O
C
C
O=
CO
Foil 2nm 6nm
Cu Au
Keywords Copper · Gold · Alloy · CO
2
reduction · Electrocatalysis · Carbon dioxide · Nanoparticle
1 Introduction
Transition metals such as Cu, Ni, Sn, and Fe have long been
considered as potential catalysts for CO
2
reduction [1–4].
Of the transition metals, Cu [5–7] has been the most heav-
ily investigated as it produces hydrocarbons at relatively
high current densities (~ 5 mA cm
−2
) and Faradaic efficien-
cies > 60% [6, 8]. Likewise, other noble metals such as Au
and Ag are known to produce CO at relatively high current
densities and Faradaic efficiencies exceeding 90% [9, 10].
Electronic supplementary material The online version of this
article (https ://doi.org/10.1007/s1080 0-018-1166-6) contains
supplementary material, which is available to authorized users.
* John Flake
johnflake@lsu.edu
1
Cain Department of Chemical Engineering, Louisiana State
University, Baton Rouge, LA 70803, USA
@Phil_Robichaud
@deepthiw
@JoseServera