Novel Approach to Non-Precious Metal Catalysts

2007 DOE HYDROGEN PROGRAM REVIEW May 15 -18, 2007, Washington, DC Novel Approach to Non-Precious Metal Catalysts Radoslav T. Atanasoski 3M Company May 15, 2007 Project ID#: FC 4 This presentation does not contain any proprietary, confidential, or otherwise restricted information Overview Timeline • Project start date: September 1, 2003 • Project end date: August 31, 2007 • Percent complete: ~95% Barriers • B. Cost • C. Electrode Performance (Technical targets: See next slide) Partners/Collaborations • Dalhousie University (subcontractor) - Prof. J. Dahn; High-throughput catalyst synthesis and basic characterization Budget • Total Project funding: $3.6 million - DOE: $2.9 million - Contractor: $0.7 million • Funding received in FY06: $967 K • Projected funding for FY07: $343 K • Brookhaven National Lab - Dr. X.-Q. Yang and Dr. W.-S. Yoon; X-Ray Absorption Spectroscopies • University of Missouri – Kansas City - Prof. D. Wieliczka; UPS at University of Wisconsin Synchrotron Radiation Center • INRS-Energie, Materiaux et Telecommunications - Prof. J-P. Dodelet; EXAFS and UPS characterization of the “model” catalyst 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 2 Objectives Goal: Develop new, lower-cost, non-precious metal (NPM) cathode catalysts for replacement of Pt in PEM fuel cells. Objectives: • • • • Reduce dependence on precious metals (Pt). Perform as well as conventional precious metal catalysts currently in use in MEA’s. Cost 50% less compared to a target of 0.2 g Pt/peak kW. Demonstrate durability of >2000 hours with <10% power degradation. Current DOE Targets: (from HFCIT Multi-Year R&D Plan) Non-Pt Catalyst Activity per volume of supported catalyst at 800 mVIR-free 2010 2015 > 130 A/cm 300 A/cm 3 3 Specific Objectives for 2007 (From last year’s future work slide, FC#12): Produce new, better-performing more durable catalysts and identify the catalytic sites. 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 3 Approach Physicochemical Characterization • XPS • XRF • SEM • XRD • Modeling • Ellipsometry • XAS (Brookhaven National Lab) • SIMS • UPS Catalyst Synthesis Functional Characterization Nanotechnology Modeling Vacuum New materials • Fuel Cell - 50 cm2 (performance and durability) - Segmented • Gas Diffusion Electrode • RRDE • Catalyst synthesis carried out via two complementary and interactive approaches both readily scalable to pilot plant level: Vacuum Processes and Nanotechnology. • Extensive physicochemical analytical characterization, including modeling work, conducted both at 3M and in collaboration with other institutions when appropriate. • Functional characterization chiefly performed in 50-cm2 FC; other techniques as required. 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 4 Technical Accomplishments • Achieved durability of over 1,000 hours with practically no irreversible performance losses − with comparable, state-of-the-art NPM catalyst activity as reported in the literature, − tested at 0.65 V under Hydrogen – Air in 50-cm2 fuel cell. • Catalytic activity 0.1 A/cm2 at 0.77 V approached the Interim Milestone #5 (0.1 A/cm2 at 0.8 V). • Fabricated higher surface area, thermally stable substrates for use with the vacuum approach. Achieved activity surpassing the best previous result by a factor of four. • Made advances in testing, characterization, and modeling that provide valuable feedback for materials development. 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 5 Nanotechnology – Durable Catalyst Support Dispersed Carbon Support 0.08 J (A/cm ) at 0.6 or 0.61V 0.06 0.04 0.02 0.00 75C cell, 30/30 psig, H2/air CF500/500 sccm, coflow. Humidity: 100%/100% 0.09 0.08 TiC Support Under AIR Higher initial performance on Higher initial performance dispersed carbon FC11137 FC11138 FC11168 FC11169 FC11909 J at 0.6V or 0.61V (A/cm ) 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0.00 0 2 2 0 20 40 60 80 100 120 Time at 0.6 or 0.65V (hours) 140 Higher J after ~ 66 hours More durable (higher J Stable performance for > 1,000 hours after ~66 hours) Performance of the catalyst supported on dispersed carbon is initially the best but decays rapidly. (See Back - up slides for nature of the catalyst) 75ºC cell, 30/30 psig, 500 sccm H2/500 sccm air, 100%/100%; Current measured at 0.6V from polarization curve after 5 hour hold at 0.65V 100 200 300 400 500 600 700 800 900 1000 FC11925-graph9 Time (hours) Materials different than dispersed carbon, conducting and electrochemically stable in fuel cell environment, were introduced as catalyst support. Performance of these catalysts is very stable and equals the best reported elsewhere. (see next slide) 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 6 Durability – Performance Comparison LANL recently published a paper in Nature detailing a new catalyst, which shows 100 hrs durability. Under similar test conditions, 3M’s catalyst after 1005 hours and LANL’s initial performance are comparable. 1.0 0.9 0.8 3M (FC11909, After 1005 hours) LANL Under OXYGEN V (Volts) 0.7 0.6 0.5 LANL - 5 cm2 cell; 80ºC, 30/30 psig, 300 sccm H2/540 sccm O2, CDP90C/CDP80C; Bashyam and Zelenay, Nature, Vol 443, 7 September 2006, 63, supp. info. 3M - 50 cm2 cell; 80ºC cell, 30/30 psig, 560 sccm H2/1000 sccm O2, CDP90C/CDP80C 0.4 0.00 0.02 0.04 0.06 0.08 0.10 J (A/cm ) 2 LANL - 5 cm2 cell; 80ºC, 30/30 psig, 300 sccm H2/540 sccm O2, CDP90ºC/CDP80ºC; Bashyam and Zelenay, Nature, Vol 443, 7 September 2006, 63, supp. info. 3M - 50 cm2 cell; 80ºC cell, 30/30 psig, 560 sccm H2/1000 sccm O2, CDP90ºC/CDP80ºC 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 7 Durable Substrate – Surface Area Effect CVs under Nitrogen 0.012 0.008 0.004 FC11909 - TiC FC11925 - TiC ink sonicated FC12027 - milled TiC FC12056 - BASELINE - TiC fired only (no NA) The substrate – TiC treated the same way without the catalyst. The surface area increased by a factor 3 – 4. FC Performance under Oxygen 0.02 0.00 -0.02 1.2 FC11909 - TiC FC11925 - TiC ink sonicated FC12027 - milled TiC FC12056 - BASELINE TiC fired (no NA) I (A/cm ) 2 0.000 -0.004 -0.008 -0.012 0.0 0.2 0.4 0.6 0.8 1.0 2 E (Volts) Summary_TiC_SiC-graph3 The ORR activity in the presence of the catalyst is orders of magnitude higher. I (A/cm ) -0.04 -0.06 -0.08 -0.10 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Summary_TiC_SiC-graph4 E (Volts) 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 8 Durable Substrate – Voltage Stability PS held at 1.2V, 1.4V, and 1.5V for 10 N2 CVs (50 mV/s) – Initial, After 1.2V, minutes; then repeated (1.2V, 1.4V, 1.5V); 1.4V, and 1.5V for 10 min and after additional 10 min at 1.2V, 1.4V, and 1.5V 75ºC, N2, 132%/132%RH. 10-2 0.4 0.2 I (Amps/50 cm 2) I (Amps/cm 2) PS_1.2V_10min_Un2Ch4.cor PS_1.4V_10min_Un2Ch4.cor PS_1.5V_10min_Un2Ch4.cor PS_1.2V_10min_Un2Ch4.cor PS_1.4V_10min_Un2Ch4.cor PS_1.5V_10min_Un2Ch4.cor 0 10-3 -0.2 Initial After 1.2V, #1 After 1.4V, #1 After 1.5V, #1 After 1.2V, #2 After 1.4V, #2 After 1.5V, #2 0 0.2 0.4 0.6 0.8 1.0 1.2 0 300 600 -0.4 T ime (Sec) E (Volts) The new substrate material – TiSi – is stable up to 1.4 V. Only after second exposure at 1.5 V, for a total of 20 minutes, considerable surface area effect is observed. 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 9 Durability – Other Catalyst Properties Larger hydrogen evolution peak (in the N2 CVs) showed greater durability. N2 CVs (50 mV/s) 0.012 Normalized durability current Normalized Current (J/Jinitial) at stated voltage 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 100 200 300 400 0.008 0.004 I (Amps/cm 2 ) 0 -0.004 -0.008 -0.012 -0.016 -0.020 Intensity of H2 evolution peak 0 0.2 0.4 0.6 0.8 1.0 FC1 2 2 45 FC1 2 1 72 FC1 1 9 09 FC1 2 1 78 FC11909 Normalized FC12178 Normalized FC12245 Normalized FC12172 Normalized 1.2 0.8 0.7 E (V olt s) 1-J/Jinit (50hours, 1) Time (hours) 1-J/Jinitial (50 hours after J/Ji=1) 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0.000 Durability This may point to surface properties of the catalyst that are essential for durability. 0.005 0.010 0.015 0.020 2 0.025 Intensity of hydrogen evolution peak (A/cm ) 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 10 Durability – Peroxide Content 100 90 80 70 a) % H2O2 60 50 40 30 20 10 00-41-2 RRDE studies performed on three different catalysts at Dalhousie University. 00-38-1 Disk Current Density [mAFaradaic.cm-2geometric] 0 b) -1 • Peroxide emission of best performing catalyst on TiC substrate is relatively low (< 10%). • Same peroxide content on the same catalyst made on carbon substrate did not result in durable product. 1 -2 -3 00-41-2 3M Samples at 900 rpm 0.1 M HClO4, room temp 5 mV.s-1, 785μg.cm-2 December 2006 -4 00-38-1 -5 0 0.2 Potential vs. RHE [V] 0.4 0.6 0.8 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 11 Thermal Treatment – The Role of Iron Thermal treatments to 550ºC, 700ºC, and 900ºC in ammonia were performed on three aliquots of the same catalyst batch. 15 J (mA /cm2) at 0.6V (O2) 20 25 30 20 • Performance increases with thermal treatment temperature, NOT THE AMOUNT OF IRON. •Nearly 1:1 correspondence of Fe content measured via XRF vs the intensity of the Fe redox in the N2 CVs. • Most Fe remains on the sample treated to 700OC. 10 8 Fe redox (mA /cm2) 7 6 5 4 500 0 750 Treatment Temp (C) 1000 Fe (XRF, arb units) 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 12 Vacuum Processes – New Substrates New higher surface area, thermally stable substrates (developed at 3M expense, utilizing 3M proprietary technology) were further improved. CVs under nitrogen of the new substrate show a large increase in surface area 0.004 ORR activity of the new substrate with vacuum deposited Fe catalyst 0.02 0.00 -0.02 2006 Review 2007 Review 0.002 I (A/cm ) 2 0.000 I (A/cm ) 2 -0.04 -0.06 -0.08 -0.10 0.0 0.2 0.4 0.6 80C Cell, 30/50 psig, CDP80/CDP80; CF180 H2/CF335 O2; CVs at 5 mV/s -0.002 -0.004 2006 Review 2007 Review 75ºC, 0/0 psig, CF500 H2/CF500 N2, 132%/132%RH 0.2 0.4 0.6 0.8 1.0 1.2 -0.006 0.0 0.8 1.0 1.2 E (Volts) E (Volts) • Performance of the new catalyst is significantly better than the best 2006 results from the vacuum approach. 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 13 Vacuum Processes – Thermal Treatment Nitrogen Loss Atomic content of N Atomic content of Co (%) (%) 14 13 12 11 10 9 40 35 30 25 20 15 10 5 70 60 50 40 30 20 10 1 0.9 0.8 0.7 0.6 0.5 2 1.6 1.2 0.8 0.4 0 600 650 700 750 800 850 900 950 1000 Heat-treatment Temperature(oC) Heterogeneity Onset Potential (V vs.RHE) Co particle size (nm) 0.1M KOH 0.1M HClO4 Current density @0.7V (mA/cm2) 0.1M KOH 0.1M HClO4 The loss of nitrogen is accompanied by a transition from homogeneity to heterogeneity in the material structure which is reflected on ORR activity as measured by RDE. (Dalhousie University) E. B. Easton, R. Yang, A. Bonakdarpour, and J. R. Dahn*, Electrochem. and Solid-State Lett., 10 1 B6-B10 2007 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 14 Future Work Remainder of project: • Fulfill reporting obligations, most notably the Final report. • Prepare manuscripts for publication and conference presentations. • Explore further the area of more durable catalysts substrates and identify the catalytic sites (will continue after completion of the Project). 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 15 Summary 0.028 0.024 0.020 0.016 0.012 Initial Durability FC11909 • In 2007, a major breakthrough in durability was achieved. • Overall, the project established new synthetic approaches and opened new avenues for further development in the NPMC world. • Strong interactive advanced characterization and modeling complement the synthetic effort. • Strong, fully-integrated collaborations supplement 3M expertise and lead to fundamental understanding of catalyst. • 12 publications, presentations, and three invited lectures. J at 0.6V (A/cm ) 2 0.008 0.004 0.000 0 performance 100 200 300 400 500 600 700 800 900 1000 1100 1200 Time (hours) FC11925-graph4 • Today, 3M’s catalysts are among the best performing and most durable NPMC tested in a real fuel cell. 1.0 0.9 Performance Progression 1000 Current at 0.6V (mA/cm2) 100 Current at 0.6 V in 50-cm FC 2 Performance Status DOE targets calculated assuming same catalyst layer thickness as for the 3M curve shown. GM Benchmark Performance 2 Pt, 0.4 mg/cm 70 mV/decade 3M, 19 A/cm 3 V (Volts) 10 1 0.8 0.7 0.6 DOE 2005 status 3 8 A/cm DOE 2010 3 130 A/cm DOE 2015 3 300 A/cm 0.1 Vacuum Nanotechnology Timeline 8/31/07 3M: 80ºC cell, 30/50 psig, 100%/100%RH H2/O2; CF180/335 sccm. Pt: 80ºC cell, 7.5/7.5 psig, 100%/100%RH; CS(2.0,139) H 2/CS(9.5,331) O2. Gasteiger et al., Applied Catalysis B: Enviromental 56(2005) 9-35 0.01 9/1/03 1E-3 0.01 2 J (A/cm ) 0.1 1 16 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 Highly Nitrogenated Carbon – HNC – for Acidic FC Catalyst activity depends on the content and the basicity of the N sites: • • • • N Requires low basicity of nitrogen sites “Pyridinic” – higher basicity “Pyrazinic” – lower basicity Model compounds (Literature values): N N N N N N pKa = 1.1 pKa = 0.37 N N pKa = 5.14 pKa = 4.85 pKa = 5.14 N pKa = 0.6 3M pKa = 4.52 17 Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 Thermal Polymerization to Form New HNC NH2 + NH2 Cat. Δ N N N N O2 N O2 N Nanoparticle support H 2N NO2 n + NO2 NH2 Cat. Δ Nanoparticle support N N N N N N n (One possible configuration) •When iron or cobalt are present, metal is retained as bonded to nitrogen •Further thermal processing increases conductivity •Metal cation is used to retain active nitrogen sites (template) •Metal can be removed with retention/enhancement of activity •Can titrate sites to examine nitrogen density and basicity •Supported on nanoparticle support for high surface area 3M Novel Approach to Non-Precious Metal Catalysts – 2007 DOE Hydrogen Program Review, May 15 – 18 18