Boosting Performance of Carbon Supported Pt Catalysts for Fuel Cell - - PowerPoint PPT Presentation

▶
boosting performance of carbon supported pt catalysts for
SMART_READER_LITE
LIVE PREVIEW

Boosting Performance of Carbon Supported Pt Catalysts for Fuel Cell - - PowerPoint PPT Presentation

Nov 24, 2023 588 likes •786 views

Boosting Performance of Carbon Supported Pt Catalysts for Fuel Cell Catalysis through Ionic Liquid Modifications Electrochemistry 2016, GOSLAR, SEPTEMBER 26 28, 2016 Gui-Rong Zhang, 1,2 Macarena Munoz, 2 Bastian J.M. Etzold 1,2 1

slide-1
SLIDE 1

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 1

Boosting Performance of Carbon Supported Pt Catalysts for Fuel Cell Catalysis through Ionic Liquid Modifications

Gui-Rong Zhang,1,2 Macarena Munoz,2 Bastian J.M. Etzold1,2

1Ernst-Berl-Institut für Technische und Makromolekular Chemie

Techniche Universität Darmstadt

2 Lehrstuhl für Chemische Reaktionstechnik (CRT)

Friedrich-Alexander-Universität Erlangen-Nürnberg

Electrochemistry 2016, GOSLAR, SEPTEMBER 26 – 28, 2016

slide-2
SLIDE 2

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 2

Research Background

A fuel cell is a device that directly converts the chemical energy into electricity

Scheme of a fuel cell device

ØBroad based applications of low temperature fuel cell technology is restricted by the its high cost

slide-3
SLIDE 3

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 3

Research Background

ØNumerous efforts have ever been made to improve the Pt activity for ORR, mainly by engineering the structures of electrocatalysts.

Research Background

slide-4
SLIDE 4

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 4

Pt catalyst IL & solvent

Modifying Pt/C catalyst with Ionic Liquids for Oxygen Reduction Reaction Synthetic strategy

u State of the art catalyst 20 wt-% Pt/C (JM) u Hydrophobic ionic liquid

Materials

[MTBD]+ [NTf2]- Solid Catalyst with Ionic Liquid Layer (SCILL) Concept

Pt

slide-5
SLIDE 5

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 5

Structural Analysis

Transmission Electron Microscopy

No observable change in Pt NP size after IL modification

slide-6
SLIDE 6

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 6

Cyclic Voltammetry Measurements

u Determination of Electrochemically

Active Surface Area (EAS)

Pt-Had Pt* + H+ + e-

2H2O + Pt* Pt-OHad + H3O+ + e-

u Determination of surface coverage

  • f oxygenated species on Pt (θOH)

Pt/C-fresh

0.1 M HClO4, 20 mV s-1, room temperature, IL = [MTBD][NTf2]

Pt/C-SCILL-2

slide-7
SLIDE 7

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 7

Cyclic Voltammetry Measurements

u Determination of Electrochemically

Active Surface Area (EAS)

Pt-Had Pt* + H+ + e-

2H2O + Pt* Pt-OHad + H3O+ + e-

u Determination of surface coverage

  • f oxygenated species on Pt (θOH)

Pt/C-fresh

0.1 M HClO4, 20 mV s-1, room temperature, IL = [MTBD][NTf2]

Pt/C-SCILL-100

slide-8
SLIDE 8

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 8

Cyclic Voltammetry Measurements

Pt/C-fresh

0.1 M HClO4, 20 mV s-1, room temperature, IL = [MTBD][NTf2]

Pt/C-SCILL-100 Ø The electrochemically active surface area reduced approx. by 19 %.

slide-9
SLIDE 9

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 9

Oxygen Reduction Reaction

Ø Half wave potential shifts pronounced by 18 mV

0.1 M HClO4, 10 mV s-1, 1600 rpm, room temperature, [MTBD][NTf2] G.R. Zhang, M. Munoz, B.J.M. Etzold, ACS Appl. Mater. Interfaces, 2015, 7, 3562; G.R. Zhang, B.J.M. Etzold, J. Energy Chem., 2016, 25, 199.

slide-10
SLIDE 10

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 10

Oxygen Reduction Reaction

Ø Above 50 % degree of pore filling: mass transfer limitation

0.1 M HClO4, 10 mV s-1, 1600 rpm, room temperature, [MTBD][NTf2]

slide-11
SLIDE 11

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 11

Ø The mole fraction of H2O2 formed during ORR is lower than 3% for both samples

ORR Pathways

slide-12
SLIDE 12

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 12

Cation Anion O2 solubility (mM) [MTBD][NTf2] 2.2 [MTBD][Beti] 2.9

ORR conditions: 0.1 M HClO4, 10 mV s-1, 1600 rpm, room temperature

O2 solubility matters?

ØSimilar volcano dependent behaviour of Pt activity on pore filling, with the maximum activity obtained at α = 50% Ø Pt activity towards ORR is not sensitive to the O2 solubility in ILs.

Reason for activity increase: O2 solubility?

slide-13
SLIDE 13

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 13 13 23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 13

Cation Anion O2 solubility (mM) [C4C1im][NTf2] 2.3

Engineering IL cation

Cation Anion O2 solubility (mM) [MTBD][NTf2] 2.2

G.R. Zhang et al. Angew. Chem. Int. Ed. 55, 2257 (2016)

slide-14
SLIDE 14

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 14

Cyclic Voltammetry Measurements

Ø The presence of [C4C1im][NTf2] imposes little effect on the EAS, while reduces the coverage of

  • xygenated species on Pt from 34.0% to 17.6%.

0.1 M HClO4, 20 mV s-1, room temperature

slide-15
SLIDE 15

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 15

Oxygen Reduction Reaction

0.1 M HClO4, 10 mV s-1, 1600 rpm, room temperature, [C4C1im][NTf2]

Ø Pt/C-[C4C1im][NTf2] exhibited the highest activity towards ORR, which is three times more active than the pristine Pt/C

slide-16
SLIDE 16

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 16

Origin of the boosting effect of IL on ORR-hydrophobicity

2H2O + Pt* Pt-OHad + H3O+ + e-

ØReaction media ØReaction product ØSource of catalyst poisons

Pt/C-fresh Pt/C-SCILL

O2-satureated N2-saturated

slide-17
SLIDE 17

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 17

Origin of the boosting effect of IL on ORR

Ø The IL would selectively locate at the “defect” sites, and suppresses the surface oxidation of Pt

G.R. Zhang, M. Munoz, B.J.M. Etzold, Angew. Chem. Int. Ed. 2016, 55, 2257

slide-18
SLIDE 18

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 18

Summary

Hydrophobicity “Poisonous” water O2 solubility § The introduction of IL could significantly improve the Pt activity and stability for ORR. § The boosting effect is not sensitive to the O2 solubility in IL, but dependent on the pore filling and geometric structures of ILs. § The boosting effect would come from the hydrophobicity conveyed by ILs, which would help prevent surface “poisoning” of Pt by H2O. § SCILL concept: a new strategy to improve the performance of electrocatalysts for fuel cells.

slide-19
SLIDE 19

23.11.17 | 07 Chemie | Ernst-Berl-Institut für Technische und Makromolekulare Chemie | Prof. BJM Etzold | 19

Acknowledgement

  • Prof. Peter Wasserscheid
  • Dr. Marco Haumann
  • Dr. Nicola Taccardi
  • Prof. Bastian Etzold
  • Dr. Macarena Munoz

Thomas Wolker Teguh Ariyanto Johannes Landwehr Jan Gläsel

This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement n° 681719)