RU-EMN Best-in-class Platinum Group Metal-free Catalyst Integrated Tandem Junction PEC Water Splitting Devices Eric Garfunkel & Charles Dismukes Rutgers, the State University of New Jersey 11/14/2017 NREL, Golden, CO
HydroGEN Kick-Off Meeting Project Vision Award # EE0008083 What is the highest possible STH performance achievable using the best-in-class PGM-free catalysts? Year 1 Funding $0.278 M NREL InGaP/GaAs + RU-OER-LiCo x O y + RU-HER-Ni x P y Bioinspired OER catalyst How does that performance change as the system is optimized for value? Replacing III-V multi-junction photoabsorbers with NREL-ZnSnN 2 photoanode & RU-SrNbO 2 N photocathode Project Impact 1 st PEC using best-in-class PGM-free ecats Unsolved tech problem: Catalyst-photoabsorber integration Solar to Hydrogen path to renewable fuels & climate benefits 50 X LiCoO 2 Cubic LiCoO 2 Layered Nafion only Interfacial layer H 2 Si TiN 2H + + 2e - HydroGEN: Advanced Water Splitting Materials 2
Innovation and Objectives Project history copi s have 5 yr running collaboration in catalysis & solar fuels. DOE-SBIR funded RU & Proton OnSite validated OER cubic LiCoO 2 beats noble-metal commercial benchmark in alkali. NSF-DOE-CBET award, forerunner of current project: Thin films of RU catalysts + oxynitride photoanodes. Proposed targets yr 1 PV- State of the Art Performance or Value cathode Non-PGM STH > 10% GaInP 2 /GaAs Half-cell BiVO 4 J ph E=1.23V RHE anode = 1.5mA/cm 2, ZnSnN 2 Stability >90% 1h Metric Match or beat Improve Barriers Can RU-eCats replace PGMs in PECs? Make transparent thin-film PGM-free ecats Integrate them with SC-photoabsorbers Make them perform & survive in strong alkali for > 1 decade Do this with multi-junction PECs Do this at multiple sun intensities Partnerships NREL partners: Friedman/Deutsch: Integration InGaP/GaAs photoabsorbers with RU-OER-eCats Zakutayev: High-value photocathodes (ZnSnN 2 ) and p-type SrNbO 2 N for benchmarking and integration with RU-eCats. Others? HydroGEN: Advanced Water Splitting Materials 3
Technology Innovation Concept How do the best in class PGM-free ecats perform in these configs? High-performance PV High-value PV Tuner-type configuration: pn-gaas/p-gainp 2 Using the best-in-class photoabsorbers with RUeCats Benchmark STH > 10 %, stability > 24h (in the firstperiod) Low-cost photoabsorbers with RU ecats Achieving STH efficiency better than existing low-cost photoabsorber (W-BiVO 4 ) HydroGEN: Advanced Water Splitting Materials 4
Technology Innovation: Best in Class HER ecats Porous Particle Electrode Hydrogenase-inspired Nickel Phosphides 7 Ni x P y crystalline phases + W, Fe doped Thin-film fabrication: High-P content nickel phosphide Best in class efficiency Ni 5 P 4 1 μm 100 nm Ni 5 P 4 / Au in 1 M NaOH Stability more than >24 hours with less than 0.5% Ni dissolution by ICP-OES is demonstrated. Tafel = 98mV/dec Overpotential = 0.332V at -10mA/cm 2 Interface is unstable during phosphidization Tafel slope comparable to nanocrystalline cat. Laursen, A. B., et al. EES 8, 3 (2015): 1027 Hwang, S., et al ECS Trans 72, 23 (2016): 31 HydroGEN: Advanced Water Splitting Materials 5
Technology Innovation: Best in Class OER ecats Photosynthesis-inspired water oxidation ecats Cubic-LiCoO 2 & spinel-lico 2 O 4 & B site doped Mn Thin-film fabrication: Cross-section SEM AFM Commercial noble metal benchmark LiCoO 2 MEA thin film 30nm Cr 30nm LiCoO 2 90nm Au Glass Exceeds PGM performance in independent benchmarking at Proton OnSite. Tafel slope: 55mV/dec E 10mA/cm 2 = 0.42V vs RHE High stability in Proton OnSite benchmarking: > 1000 h up to 400 ma/cm 2 (length of test). Gardner, G. et al Energy Environ. Sci. 9, (2015): 3 9 HydroGEN: Advanced Water Splitting Materials 6 Hwang, S., et al ECS Trans. 72, no. 23 (2016): 31 51
Technology Innovation: PV-eCat Interfacial Diffusion Need: Interfaces that achieve unidirectional charge flow & are chemically inert. Thin film nickel phosphides 1. Earth abundant elements 2. Thin film high activity catalysts e - E o (H 2 /H 2 O) Avoid substrate diffusion (during processing) Cathode Ni x P y : Anode- LiCoO 2 p-gainp 2 pn-gaas p-srnbo 2 N n-znsnn 2 Interfacial layer 1. Anti-reflective coating 2. Thermal diffusion barrier 3. Protect photoabsorber while hydrogen evolution 4. Minimize junction impedance HydroGEN: Advanced Water Splitting Materials 7
Technology Innovation: New ecat-pv Junction Layer Thin-film fabrication of cubic NiP 2 /TiN/n + p-si: Good performance on n + Si in 0.5M H 2 SO 4 6.8 nm Ni 0.33 P 0.67 Ni 0.19 P 0.38 Ti 0.05 O 0.16 N 0.15 Ti 0.39 N 0.33 O 0.28 P doped Si P doped Si Based on RBS/XPS High photocurrent stability in 0.5M H 2 SO 4 at 0V vs RHE: 5.6 nm 4 nm Tafe slope :41mV/dec η 0h (at -10mA/cm 2 ) : 0.167 V CoP benchmark [1] : 60mV/dec η 0h (at -10mA/cm 2 ) : 0.202 V High temps synthesis causes interfacial diffusion poor PEC performance. Previously reported Ti/TiO 2 protection layers result in TM-Si formation. [2] TiN has a 10 fold lower diffusivity for Si compared to TiO 2. [3] [1] Hellstern, T. R. Adv. Energy Mater. 6, (4) (2016): 1501758. [2] Seger, B., et al. J. Mater. Chem. A 1, (47) (2013): 15089. [3] J. Libardi., et al. Vacuum 2016, 128, 178. HydroGEN: Advanced Water Splitting Materials 8
Rutgers Expertise & Facilities Materials synthesis for HER, OER & CO 2 C n PXRD + Rietveld refinement Thin film deposition techniques: PVD, PLD, ALD, electrochemical, sol-gel, etc. Dissolved H 2 & O 2 sensing, 10-9 M real-time Imaging & Composition NION UltraSTEM (Scanning Transmission Electron Microscope), with world leading EELS resolution Vibration, plasmon, interband-transition and core-shell transition capable Ion scattering - Medium Energy Ion Scattering (MEIS) and Rutherford Backscattering (RBS) Zeiss Helium Ion Microscope (HeIM) a Post-SEM method w/excellent depth of field, little charging, compositional info MoS 2 monolayer HIM image of coral 8 x 8um STEM/EELS vibrational spectra Depth (Å) HydroGEN: Advanced Water Splitting Materials 9 Scattered Yield (a.u.) Concentration MEIS spectra 2.0 1.5 1.0 0.5 depth O Si 5 BN SiO 2 TiH x Epoxy Resin 75 80 85 90 95 O Zr ZrO 2.04 Proton Energy (kev) MEIS depth profile Si 0.0 0 10 20 30 40 50 60 70 Zr
Effective Leveraging of the EMN Resource Nodes High-performance PEC: III-V MOVPE node (Deutsch/Friedman) will provide p-gainp 2 (Q1) for optimization of GaInP 2 and Ru-eCats interface. High-value PEC: High-Throughput thin film node (Zakutayev) will provide (Q1-Q2) Zn 1-x Sn x N 2 thin film on various conductive for high-value PEC. Interactions to date: Discussion with node-experts have been by email and telecon. Year 2-3: Additional, node expertise/resources in TEA analysis (TEA of H 2 production node), high-throughput to production (Ulsch) will be accessed. HydroGEN: Advanced Water Splitting Materials 10
Thank you for your attention Eric Charles Martha Garfunkel Dismukes Greenblatt Anders Shinjae Laursen Hwang HydroGEN: Advanced Water Splitting Materials 11