Direct Ethanol Fuel Cell K.Devaki CH09M001

2 Why Ethanol? High Power density Low toxicity Can be obtained from biomass Challenge Cleavage of C  C bond

3 Anode reaction: CH 3 CH 2 OH + 3 H 2 O→ 2 CO H e - Eˉ = V versus SHE Cathode reaction: 3 O H e - → 6 H 2 O E + =1.229 V versus SHE Overall reaction: CH 3 CH 2 OH + 3 O 2 → 2 CO H 2 O Eemf =1.145 V

4 1. PtSn/C (EG) 2. PtSn/C (HCHO) 3. PtSn/C (NaBH 4 ) (3.9 nm) XRD Pattern Luhua. J et al., Chinese J. of Catalysis, 27, 2006,

5 CatalystLattice Constant (nm) Bulk Pt Nanometer Pt PtSn/C (EG) PtSn/C (HCHO) PtSn/C (NaBH 4 )0.3920

6 a. PtSn/C (EG) (1.8 nm) b. PtSn/C (HCHO) (2.3 nm) c. PtSn/C (NaBH 4 ) (4.2 nm) TEM Images and Particle size distribution

7 1. PtSn/C (EG) 2. PtSn/C (HCHO) 3. PtSn/C (NaBH 4 ) TPR Profile

8 1. PtSn/C (EG) 2. PtSn/C (HCHO) 3. PtSn/C (NaBH 4 ) 4. Pt/C (JM) CV ResultCell performance of DEFC 6.9 mA 4.2 mA 2.5 mA

9 PtSn/C (EG) has better EOR activity due to Smaller particle size (1.8 nm) Suitable dilation of Pt crystal lattice -OH species on SnO 2 at a lower potential

10 Schematic mechanism of ethanol electrooxidation at Pt–Sn/C and Pt–Ru/C electrodes Antolini. E et al., Electrochem. Comm, 9,2007,

11 (a) XRD patterns of binary Pt–Sn/C (1:1) and ternary Pt–Sn–Ru/C (1:1:0.3 and 1:1:1) (b) Detailed fcc Pt–Sn (3 1 1) peak. (  ) Pt–Sn solid solution; (  ) SnO 2. XRD Pattern

12 HRTEM image at low-magnification (a), histogram of particle size distribution (b) and HRTEM image at high-magnification (c) of the Pt–Sn–Ru/C (1:1:0.3) catalyst. Mean Dia: 3.2 nm

13 LSV for ethanol oxidation on binary Pt–Sn/C (1:1) and ternary Pt–Sn–Ru/C (1:1:0.3 and 1:1:1) catalysts prepared by the FAM and on commercial Pt/C and Pt–Ru/C by E-TEK electrocatalysts in 1.0 mol L −1 ethanol at (a) room temperature, (b) 40 and (c) 90 °C.

14 Enhancement in the ethanol oxidation activity on the Pt–Sn–Ru (1:1:0.3) can be due to synergic effect of Ru and Sn oxides smaller particle size The lower EOR activity of the Pt–Sn–Ru/C (1:1:1) catalyst replacement of Pt–SnO 2 interactions with Pt–RuOx interactions. Ru/Sn ratio, is the key parameter

15 (A) XRD patterns of as-prepared and thermally treated at 200 and 500 °C Pt75Sn25/C catalysts: (  ) Pt 3 Sn; (○) PtSn; (*) fcc Pt-Sn solid solution; (×) unknown peak. (B) Detailed SnO2 (1 0 1) and SnO2 (2 1 1) peaks of the as-prepared catalyst. Colmati. F et al., Applied Catalysis B: Environmental, 73, 2007,

16 Low-magnification HRTEM and particle size distribution of the (a) of the as-prepared Pt75Sn25/C catalyst by FAM (b) Pt 75 Sn 25 /C catalyst by FAM thermally treated at 200 °C (c) Pt75Sn25/C catalyst by FAM thermally treated at 500 °C.

17 High-magnification HRTEM micrograph of the (a) of the as-prepared Pt75Sn25/C catalyst by FAM (b) Pt75Sn25/C catalyst by FAM thermally treated at 200 °C (c) Pt75Sn25/C catalyst by FAM thermally treated at 500 °C.

18 COads stripping voltammograms of as-prepared and thermally treated at 200 and 500 °C Pt 75 Sn 25 /C catalysts by FAM and commercial Pt/C and Pt 3 Sn/C by E-TEK electrocatalysts recorded at 10 mV s−1.

19 Linear sweep voltammograms for ethanol oxidation on as-prepared and thermally treated at 200 and 500 °C Pt75Sn25/C catalysts by FAM and commercial Pt/C and Pt3Sn/C by E-TEK electrocatalysts in 1.0 mol L−1 ethanol at (a) 40 °C and (b) 90 °C.

20 PtSn/C-200 °C has better activity due to Smaller particle size Presence of the Pt 3 Sn phase Cleaning effect of the thermal treatment

21 Fig. 2. XRD patterns of: (a) PtSn-1 (Successive reduction); (b) PtSn-2 (Co reduction). Jiang. L et al., Electrochimica Acta, 50, 2005, nm 2.6 nm

22 CatalystLattice Constant (nm) Bulk Pt PtSn PtSn

23 HRTEM micrographs of: (a) PtSn-1 and (b) PtSn-2.

24 Cyclic voltammograms of PtSn/C electrode in 0.5 M H2SO4 electrolyte at 50 mV s−1 at room temperature. Cyclic voltammograms of PtSn/C electrode in 0.5 M H2SO4 + 1 M EtOH at room temperature. Scan rate: 100 mV s−1.

25 Current density–time dependence measured by the CA method in 0.5 M EtOH M H2SO4 solution on PtSn-1 and PtSn-2 electrodes mA mA

26 Comparison of single cell polarization curves for the DEFC using PtSn-1 or PtSn-2 as the anode catalyst (1.5 mg Pt cm−2); operation temperature: 90 °C; ethanol concentration: 1.0 M;

27 Table 1. Pt:Sn and Pt:Sn:Ni atomic ratios and mean particle size of the prepared electrocatalysts ElectrocatalystNominal atomic ratioAtomic ratio − EDX (±5%)Particle size a (nm) a The electron beam spot size used was 200 μm. a Mean particle size calculated from X-ray diffraction data using the Debye–Scherrer equation. X-ray diffractograms of PtSn/C and PtSnNi/C electrocatalysts XRD Pattern Spinace et al. Electrochem. Comm., 7, 2005,

28 CV of PtSn/C and PtSnNi/C electrocatalysts in 0.5 mol L−1 H2SO4 with a sweep rate of 10 mV s−1 CV of PtSn/C and PtSnNi/C electrocatalysts in 0.5 mol L−1 H2SO4 containing 1.0 mol L−1 of ethanol with a sweep rate of 10 mV s−1.

29 Current–time curves at 0.4 and 0.5 V in 1 mol L−1 ethanol solution in 0.5 mol L−1 H2SO4 for PtSn/C 50:50 and PtSnNi/C 50:40:10 electrocatalysts.

30 XRD patterns of different carbon-supported bi- and tri- metallic Pt-based catalysts. Zhou, W. J. et al., Journal of Power Sources, 131(2004)

31 XRD patterns of different carbon-supported Pt-based bimetallic electrocatalysts: 1) Pt 1 Pd 1 /C 2) Pt 1 W 1 /C 3) Pt 1 Sn 1 /C 4) Pt 1 Ru 1 /C 5) Pt/C PtPd/C PtW/C PtSn/C PtRu/C Pt/C

32 CV results of different anode catalysts for ethanol electro-oxidation. Temperature: 25 °C, Scan rate: 10 mV/s Electrolyte: 1.0 M EtOH M H 2 SO 4

33 At 90 °C, Anode catalyst: (○) Pt1Ru1/C; ( ▼ ) Pt1Ru1W1/C; ( * ) Pt1Ru1Mo1/C; ( ◊ ) Pt1Ru1Sn1/C. The metal loading in anode is always 1.3 mg Pt/cm2 At 90 °C; Anode catalyst and metal loading: (□) Pt/C, 2.0 mg Pt/cm2; ( ▼) Pt1Pd1/C, 1.3 mg Pt/cm2; ( * ) Pt1W1/C, 2.0 mg Pt/cm2; ( ) Pt1Ru1/C, 1.3 mg Pt/cm2; (◊ ) Pt1Sn1/C, 1.3 mg Pt/cm2;

34 CatalystLattice parameter (nm) Peak position (deg.) Particle size(nm) Pt 2 Sn/C Pt 3 Sn/C Pt 4 Sn/C Pt 3 Sn alloy Pt Guo, Y. et al., Electrochimica Acta 53 (2008) 3102–3108

35 A A A) TEM micrograph of Pt 3 Sn/C catalyst B) IR spectra of active carbon (Vulcan XC-72R) before and after pretreatment. C) TPR profile of Pt 3 Sn/C catalyst. B B C C

36 CV on Pt 3 Sn/C prepared on different carbon supports in 0.5 M H 2 SO 4. Scan rate: 10 mV s −1 Cyclic voltammograms in 1 M CH 3 CH 2 OH M H 2 SO 4 on Pt/C (JM) and Pt 3 Sn/C prepared by formic acid reduction for different times. Pt loading: mg. Scan rate: 50 mV s −1

37 Cyclic voltammograms on Pt 3 Sn/C prepared by carbon supports with and without pretreatment in 1 M CH 3 CH 2 OH M H 2 SO 4. Pt loading: mg. Scan rate: 50 mV s −1. The current–time curves at 0.2 V on Pt/C (JM) and Pt 3 Sn/C prepared by formic acid reduction for different times in 1 M CH 3 CH 2 OH M H 2 SO 4. Pt loading: mg

38 X-ray diffractograms of Pt/C, PtRh/C, PtSn/C, and PtSnRh/C electrocatalysts Spinacé et al., Ionics, 16 (2010) 91-95

39 Electrocatalyts Nominal atomic ratio Atomic ratio EDX Crystallite size (nm) PtRh/C50:5056:442.0 PtRh/C90:1088:122.0 PtSn/C50:5052:482.5 PtSnRh/C50:40:1051:38:112.0

40 TEM (20 nm) of PtRh/C (90:10; a), PtRh/C (50:50; b), PtSn/C (50:50; c), and PtSnRh/C (50:40:10; d) electrocatalysts

41 CV of PtRh/C, PtSn/C, and PtSnRh/C electrocatalysts in 1 mol L−1 ethanol solution in 0.5 mol L−1 H2SO4 with a sweep rate of 10 mV s−1, considering only the anodic sweep

42 Current–time curves at 0.5 V in 1 mol L−1 ethanol solution in 0.5 mol L−1 H2SO4 for PtRh/C, PtSn/C, and PtSnRh/C electrocatalysts

43 I–V curves of a 5-cm2 DEFC and the power density at 100 °C using PtRh/C, PtSn/C, and PtSnRh/C electrocatalyst anodes.C E-TEK electrocatalyst cathode and ethanol (2.0 mol L−1).

44 Supporting Material

45 Support Material Ideal support characteristics -High electrical conductivity -Adequate metal-support interactions at the electrode -Good corrosion resistance under oxidizing conditions – Supports-Carbon Black, Carbon or graphite nanofibers, CNT, Mesoporous Carbon. Carbon frequently used as catalyst supports -Stability in both acidic and basic media -good electric conductivity -High specific surface area -Strong influence on metal catalysts ( particle size, morphology, size distribution, alloyed degree, stability and dispersion)

46 Traditional methods for porous carbon synthesis - Chemical activation, physical activation and combination of both. -Catalytic activation of carbon precursors. -Carbonization of polymer blends. -Carbonization of polymer aerogel. Template Synthetic procedure for porous carbon -Preparation of carbon precursor/inorganic template composite -Carbonization of carbon precursor -Removal of inorganic template Templates - Silica nanoparticles(silica sol) -Zeolites -Anodic alumina membranes -Mesoporous silica materials

47

48 Mesoporous Carbon

49 Mesoporous Carbon (CMK-1) MCM-48+ Sucrose/furfural alcohol+H 2 SO 4 +H 2 O Dried 100°C 6 h and 160 °C 6 h Black Powder Sucrose/furfural alcohol+H 2 SO 4 +H 2 O Carbonized at 900 ° C for 6 h under N 2 atm. Washed with 2.5 % NaOH and EtOH CMK-1 Dried 100°C 6 h and 160 °C 6 h R.Ryoo,S.Hoon and S.Jun, J.Phys.Chem.B,103(1999)7743

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51

52 Mesoporous Carbon (CMK-3) SBA-15+ Sucrose/furfural alcohol+H 2 SO 4 +H 2 O Dried 100°C 6 h and 160 °C 6 h Black Powder Sucrose/furfural alcohol+H 2 SO 4 +H 2 O Carbonized at 900 ° C for 6 h under N 2 atm. Washed with 5 % HF and EtOH CMK-3 Dried 100°C 6 h and 160 °C 6 h Ryoo et al, J.Am.Chem.Soc, 122 (2000) 10712

53 Schematic representation CMK-3

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55 Microporous Carbon

56 Microporous Carbon Zeolite Dried under vacuum at150 °C Contact with acrylonitrile vapor for 1 d Acrylonitrile/zeolite complex PAN/zeolite Carbon/zeolite complex Washed with HF and HCl Microporous carbon Heated at rate of 5 °C/min to 700°C Held for 3 h T.Kyotani, T.Nagai, S.Inoue and A.Tomita, Chem.Mater. 1997,9,609 Evacuation for 30 min Γ-ray radiation Zeolite Impregnated with FA at RT & reduced pressure Mixture stirred for 5 d Filtered and washed with mesitylene Polymerization Heated under N 2 flow at 80°C for 24 h 150°C for 8 h PAN/zeolite

57 Microporous Carbon (By two step method) Dry zeolite powder * *+furfural alcohol Impregnation under Reduced pressure and at RT stirred for 5 days Filtered and washed with mesitylene FA/zeolite composite Polymerized at 150 ° C under N 2 atm. Microporous Carbon Z.Ma, T.Kyotani, A.Tomita, Chem.Commnu., (2000)2365 **Na-form,SiO 2 /Al 2 O 3 =5.6 Carbonized at 700 ° C for 4 h Washed with HF and HCl Propylene (2%in N 2 ) passed for 4 h Temp increased to 800 ° C

58 Z.Ma, T.Kyotani, A.Tomita, Chem.Commnu., (2000)2365

59 High surface area Microporous Carbon Dry zeolite powder * *+furfural alcohol Impregnation under Reduced pressure and at RT stirred for 8 h under N 2 flow Filtered and washed with mesitylene FA/zeolite composite PFA/zeolite composite Microporous Carbon Kyotani et al, Chem.Materials., (2001)4413 **Na-form,SiO 2 /Al 2 O 3 =5.6 Carbonized at 700 ° C Heat treated at 900°C for 3 h under N 2 flow Washed with 46% HF( 3 h) Refluxed in cocn.HCl at 60° C( 3 h) Propylene (2%in N 2 ) passed for 4 h Heating under N 2 flow at 80°C for 24 h and 150°C for 8 h

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