Electronic Supplementary Information

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Pyridinic-N-dominated carbon frameworks with porous

tungsten trioxide nano-lamellae as a promising bi-functional

catalyst for Li-oxygen batteries

Tie Liu, a Xiuhui Zhang, a Tao Huang, b and Aishui Yu a,*

a Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key

Laboratory of Molecular Catalysis and Innovative Materials, Institute of New Energy, Fudan University, Shanghai

200438, China.

b Laboratory of Advanced Materials, Fudan University, Shanghai 200438, China.

＊Corresponding Author: Tel.: +86-21-51630320; Fax: +86-21-51630320; E-mail: asyu@fudan.edu.cn.

Electronic Supplementary Material (ESI) for Nanoscale.This journal is © The Royal Society of Chemistry 2018

Liu et al, Pyridinic-N-dominated carbon frameworks with porous tungsten trioxide nano-lamellae as a promising bi-functional catalyst for Li-oxygen batteries

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Materials Synthesis

Synthesis of N-doped carbon frameworkIn typical synthesis procedure performed as follows: graphitic carbon nanotubes (CNTs, Aladdin) were mixed with pristine graphene oxide under the addition of melamine (C3H6N6, 99%, Aladdin) as N source to form a graphene homogenous slurry under room-temperature condition. After freeze-drying, the sample was annealed at 500 °C for 1 h and next 800 °C for 2 h in N2 atmosphere with a ramping rate of 5

°C/min, yielding the N-doped carbon matrix product.Synthesis of porous W-NCG compositeIn brief, as-prepared N-doped carbon product was dispersed in deionized water by ultrasound and mixed together with sodium tungstate dihydrate (99.5 % purity Na2WO4·2H2O) under mild magnetic stirring for overnight. Next, a moderate amount of acidic solution (HCl, 2M) was added dropwise into the solution above at a controlled rate until pH value of the whole solution was adjusted to 2. Then, it was transferred into a Teflon-lined stainless-steel autoclave and kept at 160 °C for 10 h. After cooling down, obtained precipitate was washed alternately by distilled water and ethanol several times prior to being dried after freeze drying. Finally, the target sample is collected after the calcination process at 650 °C for 2 h under N2 atmosphere with a heating rate of 5 °C/min.

To investigate the effect of WO3 amount for comparison, we prepared W-NCG nanosheets with different NCG amounts by adding more NCG powder (denoted as W-NCG (0.5:1), W-NCG (1:1), W-NCG (2:1), respectively) while the other conditions remained same.

Synthesis of porous W-G nano-lamellae and pure WO3 sample

100 mg pristine GO, Na2WO4·2H2O (99.8 % purity, 1 mmol) and sodium oxalate (99.8 % purity Na2C2O4, 2 mmol) were added and dissolved ultrasonically into the above solution. Similarly, the solution was adjusted to PH = 2 by using 2 M HCl solution under vigorous stirring. Then, the above mixture was transferred into a Teflon-lined stainless-steel autoclave and kept at 160 °C for 10 h. The autoclave was cooled down naturally after the reaction. The solid-precursor material was then collected by symmetric centrifugation and washed several times with ethanol and distilled water by turn to remove the excess cations and ions. Finally, a fine powder (the target simples) was obtained after freeze drying and calcination process at 650 °C for 2 h under N2 atmosphere, which was collected for characterization and analysis further. For comparison, pure WO3 sample was also obtained in the absence of GO solution.

Liu et al, Pyridinic-N-dominated carbon frameworks with porous tungsten trioxide nano-lamellae as a promising bi-functional catalyst for Li-oxygen batteries

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Fig. S1 XRD spectra of W-NCG sample, NCG, pristine GO and the corresponding

PDF standard card of WO3 (20-1324).

Fig. S2 (a) Cross-section SEM image of W-NCG at a low magnification.

Liu et al, Pyridinic-N-dominated carbon frameworks with porous tungsten trioxide nano-lamellae as a promising bi-functional catalyst for Li-oxygen batteries

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Fig. S3 (a) XRD spectra of WO3@graphene and pure WO3 nano-lamellae after annealing, (b) the

EDS spectra of WO3@graphene sample.

Fig. S4 WO3@graphene sample: (a) SEM image, (b-d) TEM, HRTEM and SAED images,

respectively; Pure WO3 nano-lamellae sample after annealing: (e) SEM and the inset is detailed

enlarged SEM image (f) TEM image and inset is schematic image of WO3 lamellae.

Liu et al, Pyridinic-N-dominated carbon frameworks with porous tungsten trioxide nano-lamellae as a promising bi-functional catalyst for Li-oxygen batteries

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Fig. S5 Nitrogen adsorption and desorption isotherms and pore-size distributions of the as-

prepared: (a) pure WO3 and (b) NCG sample.

Liu et al, Pyridinic-N-dominated carbon frameworks with porous tungsten trioxide nano-lamellae as a promising bi-functional catalyst for Li-oxygen batteries

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Fig. S6 Rate performance of LOBs with different cathodes: (a) W-NCG (1:1), (b) W-NCG

(2:1) and (c) W-G, inset is the corresponding columbic efficiency; (d) Comparisons

discharged profiles of the batteries using W-NCG (0.5:1) and pure WO3 cathodes at

different current densities.

Liu et al, Pyridinic-N-dominated carbon frameworks with porous tungsten trioxide nano-lamellae as a promising bi-functional catalyst for Li-oxygen batteries

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Fig. S7 Rate performance of LOBs with pure WO3 sample, inset is the corresponding

columbic efficiency.

Liu et al, Pyridinic-N-dominated carbon frameworks with porous tungsten trioxide nano-lamellae as a promising bi-functional catalyst for Li-oxygen batteries

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Fig. S8 The discharge-charge curves of pure WO3 electrode with a fixed capacity of 1000

mAh g-1 at a current density of 0.1 mA cm-2.

Liu et al, Pyridinic-N-dominated carbon frameworks with porous tungsten trioxide nano-lamellae as a promising bi-functional catalyst for Li-oxygen batteries

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Fig. S9 Morphologies of W-NCG cathodes at various states: SEM images of (a) pristine

state, (b) after discharge, (c) after charge and (c) after 83 cycle. The white space bar is

1µm.

Fig. S10 TEM image of W-NCG cathode after 1st discharge.

Liu et al, Pyridinic-N-dominated carbon frameworks with porous tungsten trioxide nano-lamellae as a promising bi-functional catalyst for Li-oxygen batteries

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Table. S1 Summary of the detail of as-prepared samples.

Raman XPS BETSample

D band/cm-1 G band/cm-1 ID/IG ratio N Con. (at %) S.A/(m2 g-1)

W-NCG 1330 1590 1.35 4.7 % 165.6

W-G —— —— —— —— 106.4

NCG 1334 1580 0.98 6.4 % 262.4

G 1332 1578 0.87 —— ——

WO3 —— —— —— —— 42.3

Note: Con., Concentration; S.A., Specific area.

Liu et al, Pyridinic-N-dominated carbon frameworks with porous tungsten trioxide nano-lamellae as a promising bi-functional catalyst for Li-oxygen batteries

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Table. S2. Comparisons of the cell performance with different cathodes reported recently.

Cathode ElectrolyteCur.

Den.

Spec.

Cap./(mAh/g)Cycles Ref.

Co/CoO-graphene 1 M LiCF3SO3 in TEGDME 100 mA/g ~4100 60/(fixed 500) [S1]

Pd/Co3O4 1 M LiTFSI in TEGDME 0.05 mA/cm2 1814 ~6/(fixed 500) [S2]

3D N-doped C 1 M LiTFSI in TEGDME 100 mA/g ~3200 161/(fixed 600) [S3]

CNT@RuO2 ~4500~100/(fixed

500)

CNT

LiTFSI in TEGDME (1:5) 385 mA/g

~3300 none

[S4]

CNTs film 1 M LiPF6 in TEGDME 200 mA/g 3400 ~40/(fixed 500) [S5]

Co@N-CFs ~4600 <40/(fixed 500)

CFs1 M LiTFSI in TEGDME 100 mA/g

~600 <5/(fixed 500)[S6]

N-doped CNTS 1 M LiPF6 in DMSO 0.05 mA/cm2 1814 ~8 [S7]

Mn-Ru Oxide 1 M LiCF3SO3 in TEGDME 0.1 mA/cm2 ~6500 ~50 [S8]

MnOOH/G 1 M LiCF3SO3 in TEGDME 100 mA/g ~380 none [S9]

cube ~3746Co3O4

sheet ~4560

CNTs

1 MLiNO3 in DMSO 200 mA/g

~2900

none [S10]

N-doped CNTS 1 M LiPF6 in PC/EC (1:1) 75 mA/g ~850 none [S11]

PPy/AGCA ~5250 ~90

AGCA1 M LiTFSI in TEGDME 200 mA/g

<3500 <30[S12]

N-doped CNTs/Ni-foam 1 M LiPF6 in DMSO 0.3 mA/cm2 4650 ~26 [S13]

MnO2@ TiN 100 mA/g ~3150 200/(fixed 500)

Ir@TiN 100 mA/g ~2600 200/(fixed 500)

Commercial Pt/C

1 M LiN(CF3SO2)2 in

TEGDME100 mA/g ~3200 < 80/(fixed 500)

[S14]

Ordered mesoporeous

carbon1 M LiNO3 in DMAc 100 mA/g 4036

~70/(fixed

1000)[S15]

WO3 1 M LiTFSI in TEGDME 0.05 mA/cm2 4460<50/(fixed

1000)

This

work

W-G 1 M LiTFSI in TEGDME 0.05 mA/cm2 4775 noneThis

work

W-NCG (0.5:1) 1 M LiTFSI in TEGDME 0.05 mA/cm2 7850~83/(fixed

1000)

This

work

Note: Cur. Den., current density; Spec. Cap., specific capacity; Ref., references.

Liu et al, Pyridinic-N-dominated carbon frameworks with porous tungsten trioxide nano-lamellae as a promising bi-functional catalyst for Li-oxygen batteries

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