Near Ambient Pressure Electrochemical X-Ray Photoelectron Spectroscopy (E-XPS)


Sandia National Laboratories (SNL)

Capability Expert

Farid El Gabaly



Node Readiness Category

3: High-Temperature Electrolysis (HTE)
3: Low-Temperature Electrolysis (LTE)
3: Photoelectrochemical (PEC)
3: Solar Thermochemical (STCH)


Ambient pressure Electrochemical XPS (E-XPS) is used to study surface/gas reactions in electrolyzer materials and electro-catalysts for water splitting and other oxygen reduction reactions, close to operating conditions of temperature and pressure). E-XPS measurements reveal 1) the chemical identity of the adsorbed reaction inter-mediates, and 2) the chemical state of the active materials. This important information is obtained simultaneously with traditional electrochemical characterization (voltammetry, impedance spectroscopy). A full characterization of surface electrochemistry requires knowledge of the composition and chemical state of the electro-catalyst/electrolyte surfaces. Electrochemical XPS provides this information, which is particularly important for transition-metal oxides such as perovskite catalysts, iron oxide phases, ceria (CeO2-x) and other oxide electrocatalysts.  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.

Unique Aspects‎

Unique, in-house designed and fabricated electrochemical sample holder for XPS. In-operando electrochemistry and temperature while collecting XPS information. Reaction chamber attached to the system for surface/gas chemistry measurements.


The capability is available to staff, students, and visitors of SNL-CA in Livermore, CA.


E-XPS can help discover reaction mechanisms, intermediary species, and bottlenecks in electrocatalytical reactions at the gas/surface interface.


Equipment: XPS electron energy analyzer SPECS PHOIBOS150

Near-ambient pressure XPS electron energy analyzer SPECS PHOIBOS150.

Equipment in use: High-temperature (800C) test of a solid-oxide ceramic electrolyzer device using our unique electrochemical holder

High-temperature (800C) test of a solid-oxide ceramic electrolyzer device using our unique electrochemical holder.

Exterior view of SNL's electrochemical XPS system

Overview of the electrochemical XPS system.


None with this specific instrument.