Topics in Current Chemistry (2018) 376:41
1 3
In principle, the strength of CO adsorption a on metallic surface could be used
to predict the catalyst selectivity in CO 2 electroreduction. Literature studies have
demonstrated that the surface d-band center can be theoretically predicted, and
experimental assessment showed a strong effect on surface adsorption [43–45].
The formation of bimetallic bonds often modifies the surface d-band center
[46]. Kim et al. reported the CO 2 reduction results for AuCu alloy nanomaterials with different ratio of Au and Cu [37]. Among them, Au 3 Cu nanoparticles
(NPs) showed a high CO FE of 66% and a mass activity of 230A/g at − 0.73 V
vs. reversible hydrogen electrode (RHE, all voltages are on the RHE scale unless
stated otherwise) in Fig. 1. Density functional theory (DFT) calculations revealed
that the larger Au composition in CuAu induces a lower surface binding energy
by modifying the d-band center. Lower binding energy for intermediates, such
Table 1 Bimetallic electrocatalysts for CO 2 reduction to CO
a Based on geometric area of electrode
b Based on catalyst surface area; some values are estimated from the reported data
Catalysts
Electrolyte
Potential
(V vs.
RHE)
CO partial
current density
(mA/cm
2 )
a
CO partial
current density
(mA/cm
2 )
b
Faradaic
efficiency
(%)
References
PLD
Au 0.87 Cu 0.13
0.1 M KHCO 3 − 0.8
4.34
2.9
90
[23]
Cu 85 Pt 15
0.5 M KHCO 3 − 1.11
1.5
0.17
25
[27]
Cu–Sn
0.1 M KHCO 3 − 0.6
1.0
1.35
90
[28]
Cu 5.6 Sn
0.05 M
NaHCO 3
− 0.87
0.6
0.54
67
[29]
Cu 5 Zn 8
0.05 M
NaHCO 3
− 0.87
0.95
0.86
80
[29]
AuCu
(ordered)
0.1 M KHCO 3 − 0.77
3.6
1.4
80
[30]
Ag 57 Cu 43
0.5 M KHCO 3 − 1.05
5.7
1.9
12.5
[9]
Ag/Cu foam
0.5 M KHCO 3 − 0.93
6.7
2.68
37
[31]
Au 57 Pt 43
0.1 M KHCO 3 − 0.7
0.32
0.84
30
[32]
Au coated Cu
NWs
0.5 M KHCO 3 − 0.65
12
6
30
[24]
Cu 87 Sn 13
0.1 M KHCO 3 − 1
0.55
0.46
60
[33]
CdCu
0.1 M KHCO 3 − 1.24
5
4.5
61
[34]
Cu–In
0.1 M KHCO 3 − 0.6
0.99
0.0034
90
[35]
Pd 85 Cu 15
0.1 M KHCO 3 − 0.89
6.9
0.28
86
[26]
Cu 0.75 In 0.25
0.5 M
NaHCO 3
− 0.7
2.5
1.25
81
[36]
Au 3 Cu
0.1 M KHCO 3 − 0.73
3
1.17
60
[37]
Cu/SnO 2
0.5 M KHCO 3 − 0.7
11
0.73
93
[38]
Au–Fe
0.5 M KHCO 3 − 0.5
N/A
18
99
[39]
Reprinted from the journal
108
1 3
In principle, the strength of CO adsorption a on metallic surface could be used
to predict the catalyst selectivity in CO 2 electroreduction. Literature studies have
demonstrated that the surface d-band center can be theoretically predicted, and
experimental assessment showed a strong effect on surface adsorption [43–45].
The formation of bimetallic bonds often modifies the surface d-band center
[46]. Kim et al. reported the CO 2 reduction results for AuCu alloy nanomaterials with different ratio of Au and Cu [37]. Among them, Au 3 Cu nanoparticles
(NPs) showed a high CO FE of 66% and a mass activity of 230A/g at − 0.73 V
vs. reversible hydrogen electrode (RHE, all voltages are on the RHE scale unless
stated otherwise) in Fig. 1. Density functional theory (DFT) calculations revealed
that the larger Au composition in CuAu induces a lower surface binding energy
by modifying the d-band center. Lower binding energy for intermediates, such
Table 1 Bimetallic electrocatalysts for CO 2 reduction to CO
a Based on geometric area of electrode
b Based on catalyst surface area; some values are estimated from the reported data
Catalysts
Electrolyte
Potential
(V vs.
RHE)
CO partial
current density
(mA/cm
2 )
a
CO partial
current density
(mA/cm
2 )
b
Faradaic
efficiency
(%)
References
PLD
Au 0.87 Cu 0.13
0.1 M KHCO 3 − 0.8
4.34
2.9
90
[23]
Cu 85 Pt 15
0.5 M KHCO 3 − 1.11
1.5
0.17
25
[27]
Cu–Sn
0.1 M KHCO 3 − 0.6
1.0
1.35
90
[28]
Cu 5.6 Sn
0.05 M
NaHCO 3
− 0.87
0.6
0.54
67
[29]
Cu 5 Zn 8
0.05 M
NaHCO 3
− 0.87
0.95
0.86
80
[29]
AuCu
(ordered)
0.1 M KHCO 3 − 0.77
3.6
1.4
80
[30]
Ag 57 Cu 43
0.5 M KHCO 3 − 1.05
5.7
1.9
12.5
[9]
Ag/Cu foam
0.5 M KHCO 3 − 0.93
6.7
2.68
37
[31]
Au 57 Pt 43
0.1 M KHCO 3 − 0.7
0.32
0.84
30
[32]
Au coated Cu
NWs
0.5 M KHCO 3 − 0.65
12
6
30
[24]
Cu 87 Sn 13
0.1 M KHCO 3 − 1
0.55
0.46
60
[33]
CdCu
0.1 M KHCO 3 − 1.24
5
4.5
61
[34]
Cu–In
0.1 M KHCO 3 − 0.6
0.99
0.0034
90
[35]
Pd 85 Cu 15
0.1 M KHCO 3 − 0.89
6.9
0.28
86
[26]
Cu 0.75 In 0.25
0.5 M
NaHCO 3
− 0.7
2.5
1.25
81
[36]
Au 3 Cu
0.1 M KHCO 3 − 0.73
3
1.17
60
[37]
Cu/SnO 2
0.5 M KHCO 3 − 0.7
11
0.73
93
[38]
Au–Fe
0.5 M KHCO 3 − 0.5
N/A
18
99
[39]
Reprinted from the journal
108