Near Ambient Pressure XPS at Sandia (NAP-XPS)
Category: Characterization Tools
Complete understanding of hydrogenation and dehydrogenation requires knowledge of the dynamic composition and chemical state of the surface while the reactions are taking place. The surface/gas reaction rate, believed to be a rate-limiting factor for storage materials, is controlled by the chemical and physical state of the surface and near-surface regions. Traditional XPS can only be used in ultra-high vacuum conditions, allowing only ex-situ hydrogenation experiments and subsequent XPS measurements in vacuum. But the chemical reactivity and surface species can vary greatly with and without gas pressure. Near ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) provides this information. In-situ studies with NAP-XPS can reveal the complex coupling between transport, surface reaction rates, and oxidation state changes when hydrogen storage materials (hydrides, sorbents) operate.1-9
Pressure range: UHV to 25mbar
Sample temperature: Liquid N2 to >1000 °C
Energy resolution: < 2.5 meV
Kinetic energy range: 5 - 3500 eV
Detector: fast delay-line detector with 190 ps time resolution.
Status: To be available for use in collaboration with HyMARC in late 2017.
Near-ambient pressure XPS electron energy analyzer SPECS PHOIBOS150.
1 El Gabaly, F. et al. Measuring individual overpotentials in an operating solid-oxide electrochemical cell. Phys Chem Chem Phys 12, 12138-12145, (2010).
2 Whaley, J. A. et al. Note: Fixture for characterizing electrochemical devices in-operando in traditional vacuum systems. Rev Sci Instrum 81, (2010).
3 Zhang, C. J. et al. Measuring fundamental properties in operating solid oxide electrochemical cells by using in situ X-ray photoelectron spectroscopy. Nat Mater 9, 944-949, (2010).
4 Chueh, W. C. et al. Highly Enhanced Concentration and Stability of Reactive Ce3+ on Doped CeO2 Surface Revealed In Operando. Chem Mater 24, 1876-1882, (2012).
5 El Gabaly, F. et al. Electrochemical intermediate species and reaction pathway in H-2 oxidation on solid electrolytes. Chem Commun 48, 8338-8340, (2012).
6 Chen, Q. L. et al. Observation of Oxygen Vacancy Filling under Water Vapor in Ceramic Proton Conductors in Situ with Ambient Pressure XPS. Chem Mater 25, 4690-4696, (2013).
7 Chueh, W. C. et al. Intercalation Pathway in Many-Particle LiFePO4 Electrode Revealed by Nanoscale State-of-Charge Mapping. Nano Lett 13, 866-872, (2013).
8 Feng, Z. L. A., El Gabaly, F., Ye, X. F., Shen, Z. X. & Chueh, W. C. Fast vacancy-mediated oxygen ion incorporation across the ceria-gas electrochemical interface. Nat Commun 5, (2014).
9 Gopal, C. B., El Gabaly, F., McDaniel, A. H. & Chueh, W. C. Origin and Tunability of Unusually Large Surface Capacitance in Doped Cerium Oxide Studied by Ambient-Pressure X-Ray Photoelectron Spectroscopy. Adv Mater 28, 4692-4697, (2016).