biostudies-literaturevan den Bosch ICGEuropean Research CouncilDutch Research Council (NWO)eadw6673https://www.ebi.ac.uk/biostudies/studies/S-EPMC12372890biostudies-literatureUnknown11(34)Innovative approaches to study buried interfaces and heterogeneous interactions under reaction conditions are crucial for advancing energy and catalytic materials. Our near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) setup is equipped with a tricolor x-ray source, with Al Kα, Ag Lα, and Cr Kα excitation energies, enabling information depth-selective operando and in situ analysis of solid-liquid, solid-gas, and solid-solid interfaces. We present three case studies to demonstrate the systems' capabilities. First, we compare experimental depth profiling of a LaMnO3/LaFeO3/Nb:SrTiO3 multilayer with SESSA (simulation of electron spectra for surface analysis) simulations. Second, we examine the oxidation and reduction of FexOy as a function of environment and temperature. Last, the Pt/liquid electrolyte interface is examined, revealing surface oxidation in the absence of bulk oxidation. As our results confirm, the unique combination of a NAP-XPS with the tricolor x-ray source empowers laboratory-based in situ and operando XPS characterization of advanced materials under reaction conditions in a wide range of applications.Science advancesLaboratory-based in situ and operando tricolor x-ray photoelectron spectroscopy.PMC12372890101040669175.2019.001Dietrich PMRatovskii VKoster GBu YShterk GHamed MHZaman JUSchneider MBaeumer Cvan den Bosch ICGfalseLaboratory-based in situ and operando tricolor x-ray photoelectron spectroscopy.Innovative approaches to study buried interfaces and heterogeneous interactions under reaction conditions are crucial for advancing energy and catalytic materials. Our near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) setup is equipped with a tricolor x-ray source, with Al Kα, Ag Lα, and Cr Kα excitation energies, enabling information depth-selective operando and in situ analysis of solid-liquid, solid-gas, and solid-solid interfaces. We present three case studies to demonstrate the systems' capabilities. First, we compare experimental depth profiling of a LaMnO3/LaFeO3/Nb:SrTiO3 multilayer with SESSA (simulation of electron spectra for surface analysis) simulations. Second, we examine the oxidation and reduction of FexOy as a function of environment and temperature. Last, the Pt/liquid electrolyte interface is examined, revealing surface oxidation in the absence of bulk oxidation. As our results confirm, the unique combination of a NAP-XPS with the tricolor x-ray source empowers laboratory-based in situ and operando XPS characterization of advanced materials under reaction conditions in a wide range of applications.2025-01-01T00:00:00Z2025 Aug2026-05-08T10:50:15.448Z2026-05-03T03:05:50.26ZS-EPMC123728904084511410.1126/sciadv.adw6673