Edge-State-Enhanced CO2 Electroreduction on Topological Nodal

Jan 4, 2019 - It is of great importance to explore new materials beyond conventional ones for CO2 conversions. Inspired by the edge-state-enhanced ...
1 downloads 0 Views 745KB Size
Subscriber access provided by Iowa State University | Library

C: Surfaces, Interfaces, Porous Materials, and Catalysis 2

Edge States Enhanced CO Electroreduction on Topological Nodal-Line Semimetal CuSi Nanoribbons 2

Mengyu Tang, Haoming Shen, Yu Qie, Huanhuan Xie, and Qiang Sun J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.8b08871 • Publication Date (Web): 04 Jan 2019 Downloaded from http://pubs.acs.org on January 5, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

1

Edge States Enhanced CO2 Electroreduction on Topological Nodal-line Semimetal

2

Cu2Si Nanoribbons

3

Mengyu Tang,a Haoming Shen,a Yu Qie,a Huanhuan Xie,a and Qiang Sun*a,b

4

a Department

5

b Center

of Materials Science and Engineering, Peking University, Beijing 100871, China.

for Applied Physics and Technology, Peking University, Beijing 100871, China

6 7 8

ABSTRACT

9

It is of great importance to explore new materials beyond conventional ones for CO2

10

conversions. Inspired by the edge-state enhanced conductivity in topological nodal line

11

semimetals (NLSs) and the recent advances in synthesizing NLS Cu2Si sheet, we report

12

the super performance of CO2 reduction on Cu2Si nanoribbons. Using first-principles

13

calculations, we have found that Cu2Si nanoribbons with the armchair edge (labelled as

14

A>CuSi) and zigzag edge ending with Cu or Si (labeled as Z>Cu and Z>Si) have a

15

strong reduction ability to activate CO2 to *COOH with low barriers. Especially, Z>Si

16

is most effective for further hydrogenation, displaying a capability of transferring eight

17

electrons to produce CH4 with a low free energy change of 0.24 eV. Furthermore, the

18

side reaction of hydrogen evolution reaction (HER) can also be suppressed on Z>Si,

19

exhibiting excellent performance and good selectivity for CO2 reduction.

20 21 22 23 24 25 26 27 28 29

1. INTRODUCTION 1 ACS Paragon Plus Environment

The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

30

The electrochemical reduction of carbon dioxide (CO2)1-4

Page 2 of 17

using effective

31

catalysts has been regarded as a potential method to decrease the elevated level of CO2

32

in the atmosphere. It is also helpful to develop the sustainable carbon-based economy.

33

However, electroreduction of CO2 into high-value chemicals faces some challenges5-6

34

including large overpotentials due to the weak reduction of electrocatalysts, and low

35

selectivity because of the competing HER. To overcome these obstacles, extensive

36

studies have been carried out to improve the electrocatalytic performances, and some

37

feasible strategies have been proposed7-8, such as reducing the catalyst dimension8-9,

38

introducing p-block atoms10 and inducing adsorption sites with oxophilicity.11-12 In

39

addition to these conventional strategies, using topologic materials for quantum

40

catalysis has attracted great attentions recently.11-14

41

Topological materials have fascinating surface states or edge states, which

42

stimulates the catalytic applications of topological insulator (TI)13-15 and topological

43

semimetal (TS)16. For example, two distinct families of Weyl semimetal (WSM)17

44

including 1T′-MoTe2 and NbP are reported to act as excellent electrocatalysts for H2

45

evolution reaction, where the surfaces of these materials are robust and there are no

46

significant changes in chemical composition during the catalytic process. Recently

47

HER on nodal line semimetal (NLS) TiSi family18 is also reported by using first-

48

principles calculations, and the results indicate that the high activity is mainly due to

49

the high carrier mobility and the large density of states around Fermi level, and both

50

of them are originated from the linear bands of Dirac cones in the NLS. The (0 1 0)

51

surfaces of the TiSi, TiGe and TiSn are theoretically demonstrated to display an

52

outstanding performance with the energy barrier of almost zero. Compared with these

53

3D systems, the two dimensional (2D)19-20 ones feature high surface area with more

54

low-coordinated active sites, which adds merits for utilizing 2D electrocatalysts. Then

55

an intriguing question arises naturally: Is the edge state of 2D TS effective enough for

56

CO2 conversion?

57

Recently, a 2D Dirac NLS, Cu2Si21-22 nanosheet, is reported, and the node-line

58

fermions in monolayer Cu2Si have been discovered by Angle Resolved Photo Electron 2 ACS Paragon Plus Environment

Page 3 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

59

Spectroscopy (ARPES). These new advances stimulate us to systematically investigate

60

the electrochemical activity of Cu2Si nanoribbons with different edges. We first explore

61

the possible configurations of all intermediates for finding the optimum

62

electroreduction pathways, and then calculate the free energy changes of the side

63

reaction HER to check its effect on the target reaction.

64 65

2. METHODS

66

All calculations are based on the density functional theory (DFT) using in Vienna

67

Ab-initio Software Package (VASP)23. The Perdew-Burke-Ernzerhof (PBE) functional

68

within the generalized gradient approximation (GGA)24 is used to find the preferable

69

reaction pathway. A more reliable exchange-correlation functional, the revised Perdew-

70

Burke-Ernzerhof (RPBE)25, is used to determine the free energy changes in the

71

optimum pathway. The electron-ion interaction is considered in the form of the

72

projector-augmented-wave (PAW) method26 with the kinetic energy cutoff up to 400

73

eV (Supporting Information Fig. S1). The reciprocal space is sampled using 8×1×1 and

74

7×1×1 Monkhorst−Pack27 meshes for the armchair nanoribbon and the zigzag

75

nanoribbon, respectively. The intermediate structures are fully relaxed with the total

76

energy and the force components less than 1×10−4 eV and 0.01 eV/Å, respectively. The

77

Bader analysis28-29 is used to calculate the partial atomic charges. The density of states

78

(DOS) is calculated using Gaussian smearing and the broadening factor is set as 0.05

79

eV. The binding energy30-31 Eb of adsorbate A is calculated as the following equation

80

(1).

81

Eb  E* A  E*  E A

(1)

82

Where E*A is the energy of the substrate with adsorbed A species, E* is the energy of

83

the substrate, and EA represents the energy of the single A species.

84

Computational Hydrogen Electrode (CHE) calculation model32 (in Supporting

85

Information) is employed to elucidate the electrochemical reaction pathways and

86

estimate the voltage required for different chemical pathways. The Gibbs free energy

87

change (ΔG) for all of the elementary steps are defined as the following equation (2). 3 ACS Paragon Plus Environment

The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

G  E  EZPE  T S

88

(2)

89

where E is the difference of energies calculated with DFT; EZPE is the difference

90

of zero-point energies between reactants and products, which can be calculated using

91

1 EZPE  h ; T S is the energy difference caused by the entropy effect. Because the 2

92

values of T S (T = 298.15 K) for the adsorbates are much smaller than those of the

93

gas-phase species, we only considered the entropy effects of the gas-phase molecules.

94

The corresponding corrections for species with PBE and RPBE functional are listed in

95

Table S1 and S2, respectively. The solution effects are also taken into account by

96

correcting the Gibbs free energy based on the work of Peterson et al.33, and more details

97

can be found in Supporting Information. The van-der-Waals corrections are not

98

included in our system as its influence on reaction energies is negligible as shown in

99

Table S3.

100 101

3. RESULTS AND DISCUSSION

102

3.1 Catalyst structures. As shown in Fig. 1(a) and Fig. 1(b), Cu2Si nanosheet is a

103

2D hexacoordinate metal compound. The primitive cell of Cu2Si nanosheet (as show in

104

Fig. 1(a) with blue dashed lines) contains one Si atom and two Cu atoms with the

105

optimized lattice constants a = b = 4.123 Å and the angle of 120° between two vectors.

106

Cu2Si nanosheet possesses D6h1 space group symmetry (No.191, P6/mmm) and each

107

Si atom coordinates with six Cu atoms. The thermodynamic stability of this nanosheet

108

has been proven in previous work21-22. Interestingly, the stable structures of the

109

hypercoordinate 2D materials are usually buckled, while Cu2Si nanosheet is completely

110

flat. This special planar structure is mainly contributed by the 4C-2e σ bonds22.

111

Similar to the graphene nanoribbons, the Cu2Si nanoribbon can either be in the

112

armchair configuration or in the zigzag configuration. The geometric structure of the

113

armchair ribbon (labelled as A>CuSi) is shown in Fig. 1(c). As for zigzag ribbon, Cu

114

terminated ribbon (Z>Cu) and Si terminated ribbon (Z>Si) are shown in Fig. 1(d) and

115

Fig. 1(e) respectively. Considering the CPU time limitation in DFT calculations, we 4 ACS Paragon Plus Environment

Page 4 of 17

Page 5 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

116

utilize 2×2, 2×1 and 2×2 unit cells for A>CuSi, Z>Cu and Z>Si respectively, and the

117

corresponding width of nanoribbon is 8.320, 9.521 and 14.086 Å. The distances

118

between the neighboring active sites are dA = 2.482 Å for A>CuSi, and dZ = 4.123 Å for

119

Z>Cu and Z>Si.

120

121 122

Figure 1. Geometric structures. (a) The top view and (b) the side view of Cu2Si

123

nanosheet. The top views of (c) A>CuSi nanoribbon, (d) Z>Cu nanoribbon and (e) Z>Si

124

nanoribbon. Copper and Silicon are in red and yellow, respectively.

125 126

3.2 Electronic Structures. The electronic structures of the Cu2Si nanosheet, as well

127

as the armchair and zigzag ribbons are investigated using the PBE functional. The band

128

structure and the DOS of Cu2Si nanosheet are shown in Fig. 2. As one can see, Cu2Si

129

nanosheet shows quasi-linear band crossing points within 0.8 eV bellow the Fermi level

130

along the M-Γ and Γ-K high symmetry lines. Those band touch points form two closed

131

rings in the momentum space21, which is the feature of the NLS. Additionally, the DOS

132

per atom in Cu2Si nanosheet is in the range of 0.30 to 0.50 eV-1atom-1 around ±0.2 eV

133

near the Fermi energy as plotted in Fig. 3, where as shown in shaded regions, DOS of

134

nanoribbons A>CuSi and Z>Si near the Fermi energy is much higher than that of 2D

135

Cu2Si nanosheet, suggesting the possibility of high catalytic activity in nanoribbons18.

136

5 ACS Paragon Plus Environment

The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

137 138

Figure 2. Electronic structures of Cu2Si nanosheet. The left figure is the band structure

139

and the right one is the total DOS. The red dashes show the linear dispersions near the

140

Fermi level.

141

142 143

Figure 3. DOS comparisons between 2D Cu2Si nanosheet and (a) A>CuSi, (b) Z>Cu

144

and (c) Z>Si.

145 146

3.3 Reaction pathways. After the investigation of electronic structures of Cu2Si

147

nanoribbons, we discuss the electrocatalytic performances of Cu2Si nanoribbons. CO2

148

chemisorption on three nanoribbons without a proton transfer is considered, and we

149

find *CO2 is stable for A>CuSi and Z>Cu, while it is slightly difficult for Z>Si to

150

stabilize CO2 without a proton transfer (Fig. S2). As the free energy changes of

151

*+CO2→*CO2 on A>CuSi and Z>Cu are much larger than the values of

152

*+CO2→*COOH, the first elementary step for the electrochemical reduction is one

153

electron transfer from the catalyst to CO2 simultaneously coupling with a proton from 6 ACS Paragon Plus Environment

Page 6 of 17

Page 7 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

154

the electrolyte to form *COOH or *OCHO (Supporting Information). In our

155

calculations, we consider not only the configuration *COOH with C-end adsorption

156

and C-O bridge adsorption, but also the configuration *OCHO with both O atoms

157

adsorbed on the active sites. The full free energy diagrams of the reaction pathways

158

based on the PBE functional are shown in Fig. S4-S6 in Supporting Information, and

159

the refined reaction pathways with RPBE functional are shown in Fig. 4. The

160

comparison of the free energy changes using PBE and RPBE functional for the

161

optimum reaction pathway is shown in Table S4. The free energy change for the

162

reaction pathway of CO2→*OCHO→HCOOH is much larger than that of the pathway

163

starting from *COOH, thus the reaction starting from *COOH is more possible.

164

For CO2 reduction, the first electron and proton transfer to the chemically stable

165

CO2 usually has a high overpotential34. In our system, however, the free energy changes

166

of CO2→*COOH for A>CuSi, Z>Cu and Z>Si are only 0.10 eV, 0.28 eV and 0.18 eV

167

respectively, which is much smaller as compared to that of 2D Cu2Si nanosheet (ΔG =

168

0.51 eV) (Fig. S3) and many other reported electrocatalyst like metal Cu (ΔG = 0.41

169

eV). Matching the order of the free energy differences in CO2→*COOH, the binding

170

energies of *COOH for A>CuSi, Z>Cu and Z>Si are -0.79 eV, -0.61 eV, -0.71 eV,

171

respectively. To further assess *COOH adsorptions on these catalysts, we perform

172

Bader charge analysis and plot the charge density differences as shown in Fig. 5, where

173

significant electron transfers occur mainly from the active sites to COOH. Furthermore,

174

Bader charge analyses suggest that nanoribbons donate 0.47, 0.56 and 0.47 e to COOH

175

for A>CuSi, Z>Cu and Z>Si, respectively, leading to a good binding of COOH with

176

the catalysts. In addition, the numbers of transferred electrons on the nanoribbons are

177

more than that of 2D Cu2Si sheet (0.39 e). More details on the binding behaviors are

178

given in Fig. S7. Based on the discussions above, one can see that the edge states of the

179

nanoribbons exhibit a strong reductive ability.

180

In the second electron-transfer step, *COOH couples with a proton and

181

simultaneously releases a H2O molecule to form *CO. CO binding should not be too

182

strong for the facile desorption from the active site as well as for further hydrogenation, 7 ACS Paragon Plus Environment

The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

183

otherwise the strong binding on active sites would result in catalyst poisoning. However,

184

the scaling relationship between the binding energies of the *COOH and *CO with

185

similar bonding atoms is positively correlated35-36, and the strong binding energy of

186

*COOH makes a strong CO adsorption. Among three nanoribbons, COOH binding

187

energy on A>CuSi is the strongest, resulting in a largest binding energy of *CO (Eb = -

188

1.25 eV). This strong binding energy causes a high free energy change for *CO to

189

desorb and further hydrogenate. Thus, as one can see in Fig. 4(a), the thermodynamics

190

barrier is 0.1 eV for *CO formation while 0.65 eV for *CO desorption from the

191

substrate. In contrast, as for zigzag ribbons (Z>Cu and Z>Si), the *COOH binding

192

energy is not as strong as that of the armchair nanoribbon A>CuSi, thus free energy

193

changes are different and the relevant optimum reaction pathways on Z>Cu and Z>Si

194

are shown in Fig. 4(b) and Fig. 4(c) respectively. On Z>Cu, the free energy change is

195

0.40 eV to produce CO gas, which indicates a weaker CO adsorption than that on

196

A>CuSi.

197

For Z>Si, the situations are very different from what we discussed above. The

198

binding energy of *COOH with Z>Si is moderate among three nanoribbons, and the

199

binding energy of *CO is -0.72 eV, which is also moderate and suitable for further

200

hydrogenation. Additionally, the free energy change of the potential-determining step

201

(*CO→*CHO) for deep hydrogenation on Z>Si is only 0.24 eV. A possible reaction

202

pathway is shown in Fig. 4(c) and the final product is CH4. Strikingly, different from

203

the conventional situations where the overpotentials are usually quite high in deep

204

hydrogenation37, the Si terminated zigzag ribbon (Z>Si) exhibits an excellent

205

performance on reduction CO2 to CH4 through eight-electron charge transfer process

206

with a low overpotential of 0.24 V. This low overpotential is about one third of the

207

overpotential on Cu (211) (0.74 V)33 and is also lower than the value of 0.38 V on Mo

208

edged MoSe2 nanoribbon30, indicating a high catalytic activity of Z>Si for CO2

209

reduction. More details can be found in Table 1.

210

To better understand these results, we need to go back to examine the electronic

211

structures as shown in Fig. 3, from which one can see that the catalytic performances 8 ACS Paragon Plus Environment

Page 8 of 17

Page 9 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

212

of the studied nanoribbons are closely related to their intrinsic electronic structures. The

213

DOS of A>CuSi or Z>Si near the Fermi level is obviously higher than that of Cu2Si

214

nanosheet while the situation is different for Z>Cu. This is the main reason for the better

215

catalytic performance of A>CuSi (the overpotential is 0.10 V for CO2→*COOH) and

216

Z>Si (the overpotential is 0.18 V for CO2→*COOH) than Z>Cu (the overpotential is

217

0.28 V for CO2→*COOH). In addition, in the range of -0.2 eV to -0.15 eV, the DOS

218

of A>CuSi is even higher than that of the Z>Si, resulting in the lowest free energy

219

change in catalyzing CO2 to *COOH and the strongest adsorption energy of CO for

220

A>CuSi among three nanoribbons. However, the strongest CO adsorption on A>CuSi

221

is not suitable for further desorption (ΔG = 0.65 eV) and hydrogenation (ΔG = 0.86 eV)

222

as we have discussed.

9 ACS Paragon Plus Environment

The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

223 224

Figure 4. Free-energy diagrams and the related configurations of the intermediates for

225

CO2 reduction on catalysts (a) A>CuSi, (b) Z>Cu and (c) Z>Si.

226

227 10 ACS Paragon Plus Environment

Page 10 of 17

Page 11 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

228

Figure 5. Isosurface plots with a value of 0.015 eV/Å3 of the charge density difference

229

for COOH adsorption on (a) A>CuSi, (b) Z>Cu and (c) Z>Si. The regions with purple

230

dotted lines indicate charge accumulation and the regions with green dotted lines

231

indicate charge depletion.

232 233

Table 1. Comparison of final reduction product and the corresponding overpotential

234

for CO2 reduction (‘*’ represents Ni-doped S edged MoS2, ‘**’ represents the Mo

235

edged MoSe2). Materials

Dimension

Overpotential, V

Products

Electronic band

Z>Si

1D ribbon

-0.24

CH4

NLS

3D bulk

-0.74

CH4

Metal

MoS2*30

1D ribbon

-0.28

CH4

Semiconductor

MoSe2**30

1D ribbon

-0.38

CH4

Semiconductor

AGNR>Cu38

1D ribbon

-0.48

CH3OH

Semiconductor

Cu (2 1 1)33

236 237

3.4 Side reactions. Many electrocatalysts are hampered by low Faradic efficiency

238

due to the side reaction HER. A promising electrocatalyst should not only display a low

239

overpotential for CO2 electroreduction, but also can effectively suppress the side

240

reactions. In our work, we have also studied the side reaction HER. Hydrogen evolution

241

follows either the Volmer-Tafel or the Volmer-Heyrovsky mechanism. The Tafel

242

reaction represents the process that two adsorbed H atoms react to form H2, whereas

243

the Heyrovsky reaction is the process that the adsorbed H atom reacts with another H+

244

to form H2. Those two processes can be described as the following equations (3)~(5).

245 246

* + H+ + e− ↔ *H (Volmer process)

247

*H+ + H+ + e− ↔ * + H2 (Heyrovsky process)

248

*H + *H ↔ H2 + 2* (Tafel process)

249 11 ACS Paragon Plus Environment

(3) (4) (5)

The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

250

According to Marcus theory39, the active energy of Volmer-Tafel process with two

251

electrons transferred at the same time is four times larger than that of the Volmer-

252

Heyrovsky process. In addition, the distances of the neighboring active sites for Z>Cu,

253

Z>Si (4.123 Å) and A>CuSi (2.482 Å) are significantly larger than the bond length of

254

H2 (0.74 Å), making it difficult for *H to bind with the neighboring one. In this sense,

255

we focus on the Volmer-Heyrovsky process. As shown in Fig. 6(a), the free energy

256

changes of HER for A>CuSi and Z>Cu are 0.38 eV and 0.07 eV respectively, which

257

are lower than that of the target reaction as shown in Fig. 6(b). The lower

258

thermodynamics barrier of the HER would affect the target reaction. However, different

259

from the situations on A>CuSi and Z>Cu, the free energy change of HER on Z>Si is

260

0.36 eV, which is larger than the value of 0.24 eV for the target reaction. Therefore, the

261

side reaction HER will be effectively suppressed and hence the side reaction has little

262

influence on the target reaction for Z>Si.

263 264

Figure 6. (a) Side reaction profiles of nanoribbons. (b) Free energy change comparisons

265

between the target reaction and the competition reaction.

266 267

4. CONCLUTIONS

268

In summary, we have carried out comprehensive calculations to explore the

269

performance of CO2 reduction on topological node-line semimetal Cu2Si nanoribbons.

270

We find that the armchair nanoribbon (A>CuSi) and the zigzag nanoribbon (Z>Cu,

271

Z>Si) display strong electrocatalytic activities for CO2→*COOH with small free

272

energy changes of 0.10, 0.28 and 0.18 eV, respectively. For A>CuSi and Z>Cu, the 12 ACS Paragon Plus Environment

Page 12 of 17

Page 13 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

273

most possible product is CO(g), while for the Si terminated zigzag nanoribbon Z>Si, it

274

exhibits a super performance of CO2 reduction to CH4 through eight electrons transfer

275

with a low free energy change of 0.24 eV. Moreover, the free energy change of the side

276

reaction HER is 0.36 eV which is larger than that of the target reaction, thus HER can

277

be effectively hindered. Our study not only sheds insight into CO2 quantum catalysis

278

by using topological nodal-line semimetal but also expands the applications of

279

topological quantum materials. We hope that this study can stimulate experimental

280

effort on applying quantum materials for effective CO2 conversion going beyond the

281

conventional catalysts.

282 283 284 285 286

AUTHOR INFORMATION

287

Corresponding Author

288

*E-mail: [email protected]

289

ORCID

290

Qiang Sun: 0000-0003-3872-7267

291 292

COMPETING INTRESTS

293

The authors declare no competing financial interests.

294 295

Supporting Information

296

Supporting Information is available free of charge on the ACS Publications website:

297

CHE model, the solvent corrections and entropy corrections used in our calculations,

298

the energy cutoff, van-der-Waals contributions, the thermodynamic stability of *CO2,

299

the comparison of free energy changes at PBE and RPBE levels, the pathways with

13 ACS Paragon Plus Environment

The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

300

PBE results, The PDOS profiles of the *COOH, the INCAR file and the POSCAR files

301

used in our paper.

302 303 304 305 306

ACKNOWLEDGMENTS

307

This work is partially supported by grants from the National Natural Science

308

Foundation of China (21573008, 21773003), and from the Ministry of Science and

309

Technology of China (2017YFA0204902). The calculations are supported by High-

310

performance Computing Platform of Peking University.

311 312

DATA AVAILABILITY

313

The data that support the findings of this study are available for the corresponding

314

author, Professor Qiang Sun of the Peking University (email: [email protected])

315

upon reasonable request.

316 317

REFERENCES

318 319 320 321 322 323 324 325 326 327 328 329 330 331 332

1.

Zhang, X.; Wu, Z. S.; Zhang, X.; Li, L. W.; Li, Y. Y.; Xu, H. M.; Li, X. X.; Yu, X. L.; Zhang, Z.

S.; Liang, Y. Y., et al., Highly Selective and Active Co2 Reduction Electro-Catalysts Based on Cobalt Phthalocyanine/Carbon Nanotube Hybrid Structures. Nature Communications 2017, 8. 2.

Gao, S.; Lin, Y.; Jiao, X. C.; Sun, Y. F.; Luo, Q. Q.; Zhang, W. H.; Li, D. Q.; Yang, J. L.; Xie, Y.,

Partially Oxidized Atomic Cobalt Layers for Carbon Dioxide Electroreduction to Liquid Fuel. Nature 2016, 529, 68-+. 3.

Qiao, J. L.; Liu, Y. Y.; Hong, F.; Zhang, J. J., A Review of Catalysts for the Electroreduction of

Carbon Dioxide to Produce Low-Carbon Fuels. Chemical Society Reviews 2014, 43, 631-675. 4.

Shen, H. M.; Li, Y. W.; Sun, Q., Cu Atomic Chains Supported on Beta-Borophene Sheets for

Effective Co2 Electroreduction. Nanoscale 2018, 10, 11064-11071. 5.

Kumar, B.; Asadi, M.; Pisasale, D.; Sinha-Ray, S.; Rosen, B. A.; Haasch, R.; Abiade, J.; Yarin, A.

L.; Salehi-Khojin, A., Renewable and Metal-Free Carbon Nanofibre Catalysts for Carbon Dioxide Reduction. Nature Communications 2013, 4. 6.

Asadi, M.; Kumar B.; Behranginia, A.; Rosen, B. A.; Baskin, A.; Repnin, N.; Pisasale, D.; Phillips,

P.; Zhu, W.; Haasch, R., et al., Robust Carbon Dioxide Reduction on Molybdenum Disulphide Edges.

14 ACS Paragon Plus Environment

Page 14 of 17

Page 15 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376

The Journal of Physical Chemistry

Nature Communications 2014, 5. 7.

Li, Y. W.; Sun, Q., Recent Advances in Breaking Scaling Relations for Effective Electrochemical

Conversion of Co2. Adv Energy Mater 2016, 6. 8.

Voiry, D.; Shin, H. S.; Loh, K. P.; Chhowalla, M., Low-Dimensional Catalysts for Hydrogen

Evolution and Co2 Reduction. Nat Rev Chem 2018, 2. 9.

Deng, D. H.; Novoselov, K. S.; Fu, Q.; Zheng, N. F.; Tian, Z. Q.; Bao, X. H., Catalysis with Two-

Dimensional Materials and Their Heterostructures. Nat Nanotechnol 2016, 11, 218-230. 10. Lim, H. K.; Shin, H.; Goddard, W. A.; Hwang, Y. J.; Min, B. K.; Kim, H., Embedding Covalency into Metal Catalysts for Efficient Electrochemical Conversion of Co2. Journal of the American Chemical Society 2014, 136, 11355-11361. 11. Li, Y. W.; Su, H. B.; Chan, S. H.; Sun, Q., Co2 Electroreduction Performance of Transition Metal Dimers Supported on Graphene: A Theoretical Study. Acs Catal 2015, 5, 6658-6664. 12. Shen, H. M.; Li, Y. W.; Sun, Q., Co2 Electroreduction Performance of Phthalocyanine Sheet with Mn Dimer: A Theoretical Study. J Phys Chem C 2017, 121, 3963-3969. 13. Wang, Q. S.; Wang, F.; Li, J.; Wang, Z. X.; Zhan, X. Y.; He, J., Low-Dimensional Topological Crystalline Insulators. Small 2015, 11, 4613-4624. 14. Kou, L. Z.; Ma, Y. D.; Sun, Z. Q.; Heine, T.; Chen, C. F., Two-Dimensional Topological Insulators: Progress and Prospects. Journal of Physical Chemistry Letters 2017, 8, 1905-1919. 15. Chuang, F. C.; Yao, L. Z.; Huang, Z. Q.; Liu, Y. T.; Hsu, C. H.; Das, T.; Lin, H.; Bansil, A., Prediction of Large-Gap Two-Dimensional Topological Insulators Consisting of Bilayers of Group Iii Elements with Bi. Nano Letters 2014, 14, 2505-2508. 16. Hasan, M. Z.; Xu, S. Y.; Belopolski, I.; Huang, S. M., Discovery of Weyl Fermion Semimetals and Topological Fermi Arc States. Annu Rev Conden Ma P 2017, 8, 289-309. 17. Rajamathi, C. R.; Gupta, U.; Kumar, N.; Yang, H.; Sun, Y.; Süß, V.; Shekhar, C.; Schmidt M.; Blumtritt, H.; Werner, P., et al., Weyl Semimetals as Hydrogen Evolution Catalysts. Advanced Materials 2017, 29. 18. Li, J. X.; Ma, H.; Xie, Q.; Feng, S. B.; Ullah, S.; Li, R. H.; Dong, J. H.; Li, D. Z.; Li, Y. Y.; Chen, X. Q., Topological Quantum Catalyst: Dirac Nodal Line States and a Potential Electrocatalyst of Hydrogen Evolution in the Tisi Family. Sci China Mater 2018, 61, 23-29. 19. Huo, L. L.; Liu, B. C.; Zhang, G.; Si, R.; Liu, J.; Zhang, J., 2d Layered Non-Precious Metal Mesoporous Electrocatalysts for Enhanced Oxygen Reduction Reaction. J Mater Chem A 2017, 5, 48684878. 20. Yang, Z. K.; Lin, L.; Xu, A. W., 2d Nanoporous Fe-N/C Nanosheets as Highly Efficient NonPlatinum Electrocatalysts for Oxygen Reduction Reaction in Zn-Air Battery. Small 2016, 12, 5710-5719. 21. Feng, B. J.; Fu, B. T.; Kasamatsu, S.; Ito, S.; Cheng, P.; Liu, C. C.; Feng, Y.; Wu, S. L.; Mahatha, S. K.; Sheverdyaeva, P., et al., Experimental Realization of Two-Dimensional Dirac Nodal Line Fermions in Monolayer Cu2si. Nature Communications 2017, 8. 22. Yang, L. M.; Bacic, V.; Popov, I. A.; Boldyrev, A. I.; Heine, T.; Frauenheim, T.; Ganz, E., TwoDimensional Cu2si Monolayer with Planar Hexacoordinate Copper and Silicon Bonding. Journal of the American Chemical Society 2015, 137, 2757-2762. 23. Kresse, G.; Furthmuller, J., Efficient Iterative Schemes for Ab Initio Total-Energy Calculations Using a Plane-Wave Basis Set. Phys Rev B 1996, 54, 11169-11186. 24. Perdew, J. P.; Burke, K.; Ernzerhof, M., Generalized Gradient Approximation Made Simple. Phys Rev Lett 1996, 77, 3865-3868.

15 ACS Paragon Plus Environment

The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409

25. Hammer, B.; Hansen, L. B.; Norskov, J. K., Improved Adsorption Energetics within DensityFunctional Theory Using Revised Perdew-Burke-Ernzerhof Functionals. Phys Rev B 1999, 59, 74137421. 26. Blochl, P. E., Projector Augmented-Wave Method. Phys Rev B 1994, 50, 17953-17979. 27. Monkhorst, H. J.; Pack, J. D., Special Points for Brillouin-Zone Integrations. Phys Rev B 1976, 13, 5188-5192. 28. Tang, W.; Sanville, E.; Henkelman, G., A Grid-Based Bader Analysis Algorithm without Lattice Bias. J Phys-Condens Mat 2009, 21. 29. Henkelman, G.; Arnaldsson, A.; Jonsson, H., A Fast and Robust Algorithm for Bader Decomposition of Charge Density. Comp Mater Sci 2006, 36, 354-360. 30. Chan, K.; Tsai, C.; Hansen, H. A.; Norskov, J. K., Molybdenum Sulfides and Selenides as Possible Electrocatalysts for Co2 Reduction. Chemcatchem 2014, 6, 1899-1905. 31. Zhu, G. Z.; Li, Y. W.; Zhu, H. Y.; Su, H. B.; Chan, S. H.; Sun, Q., Curvature-Dependent Selectivity of Co2 Electrocatalytic Reduction on Cobalt Porphyrin Nanotubes. Acs Catal 2016, 6, 6294-6301. 32. Norskov, J. K.; Rossmeisl, J.; Logadottir, A.; Lindqvist, L.; Kitchin, J. R.; Bligaard, T.; Jonsson, H., Origin of the Overpotential for Oxygen Reduction at a Fuel-Cell Cathode. Journal of Physical Chemistry B 2004, 108, 17886-17892. 33. Peterson, A. A.; Abild-Pedersen, F.; Studt, F.; Rossmeisl, J.; Norskov, J. K., How Copper Catalyzes the Electroreduction of Carbon Dioxide into Hydrocarbon Fuels. Energ Environ Sci 2010, 3, 1311-1315. 34. Shin, H.; Ha, Y.; Kim, H., 2d Covalent Metals: A New Materials Domain of Electrochemical Co2 Conversion with Broken Scaling Relationship. Journal of Physical Chemistry Letters 2016, 7, 4124-4129. 35. Abild-Pedersen, F.; Greeley, J.; Studt, F.; Rossmeisl, J.; Munter, T. R.; Moses, P. G.; Skulason, E.; Bligaard, T.; Norskov, J. K., Scaling Properties of Adsorption Energies for Hydrogen-Containing Molecules on Transition-Metal Surfaces. Phys Rev Lett 2007, 99. 36. Montemore, M. M.; Medlin, J. W., Scaling Relations between Adsorption Energies for Computational Screening and Design of Catalysts. Catal Sci Technol 2014, 4, 3748-3761. 37. Jiao, Y.; Zheng, Y.; Chen, P.; Jaroniec, M.; Qiao, S. Z., Molecular Scaffolding Strategy with Synergistic Active Centers to Facilitate Electrocatalytic Co2 Reduction to Hydrocarbon/Alcohol. Journal of the American Chemical Society 2017, 139, 18093-18100. 38. Zhu, G. Z.; Li, Y. W.; Zhu, H. Y.; Su, H. B.; Chan, S. H.; Sun, Q., Enhanced Co2 Electroreduction on Armchair Graphene Nanoribbons Edge-Decorated with Copper. Nano Res 2017, 10, 1641-1650. 39. Voiry, D.; Shin, H. S.; Loh, K. P.; Chhowalla, M., Low-Dimensional Catalysts for Hydrogen Evolution and Co2 Reduction. Nat Rev Chem 2018, 2, 0105.

410 411 412 413 414 415 416 417

TOC Graphic 16 ACS Paragon Plus Environment

Page 16 of 17

Page 17 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

418 419 420 421

17 ACS Paragon Plus Environment