Aqueous solution/metal interfaces investigated in operando by photoelectron spectroscopy

2015 ◽  
Vol 180 ◽  
pp. 35-53 ◽  
Author(s):  
O. Karslıoğlu ◽  
S. Nemšák ◽  
I. Zegkinoglou ◽  
A. Shavorskiy ◽  
M. Hartl ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Depth Resolution ◽  
Liquid Films ◽  
Liquid Interfaces ◽  
Heterogeneous Processes ◽  
First Results ◽  
In Operando ◽  
Solid Liquid ◽  
Electrical Bias

We describe a new in operando approach for the investigation of heterogeneous processes at solid/liquid interfaces with elemental and chemical specificity which combines the preparation of thin liquid films using the meniscus method with standing wave ambient pressure X-ray photoelectron spectroscopy [Nemšák et al., Nat. Commun., 5, 5441 (2014)]. This technique provides information about the chemical composition across liquid/solid interfaces with sub-nanometer depth resolution and under realistic conditions of solution composition and concentration, pH, as well as electrical bias. In this article, we discuss the basics of the technique and present the first results of measurements on KOH/Ni interfaces.

scholarly journals Stochastic Analysis of Electron Transfer and Mass Transport in Confined Solid/Liquid Interfaces

Surfaces ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 392-407
Author(s):  
Marco Favaro
Keyword(s):  
Electron Transfer ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Chemical Properties ◽  
Liquid Films ◽  
Liquid Interfaces ◽  
Electrical Potentials ◽  
Voltammetric Behavior ◽  
Current Densities ◽  
Solid Liquid

Molecular-level understanding of electrified solid/liquid interfaces has recently been enabled thanks to the development of novel in situ/operando spectroscopic tools. Among those, ambient pressure photoelectron spectroscopy performed in the tender/hard X-ray region and coupled with the “dip and pull” method makes it possible to simultaneously interrogate the chemical composition of the interface and built-in electrical potentials. On the other hand, only thin liquid films (on the order of tens of nanometers at most) can be investigated, since the photo-emitted electrons must travel through the electrolyte layer to reach the photoelectron analyzer. Due to the challenging control and stability of nm-thick liquid films, a detailed experimental electrochemical investigation of such thin electrolyte layers is still lacking. This work therefore aims at characterizing the electrochemical behavior of solid/liquid interfaces when confined in nanometer-sized regions using a stochastic simulation approach. The investigation was performed by modeling (i) the electron transfer between a solid surface and a one-electron redox couple and (ii) its diffusion in solution. Our findings show that the well-known thin-layer voltammetry theory elaborated by Hubbard can be successfully applied to describe the voltammetric behavior of such nanometer-sized interfaces. We also provide an estimation of the current densities developed in these confined interfaces, resulting in values on the order of few hundreds of nA·cm−2. We believe that our results can contribute to the comprehension of the physical/chemical properties of nano-interfaces, thereby aiding to a better understanding of the capabilities and limitations of the “dip and pull” method.

Solid-liquid interfaces studied with synchrotron-based ambient pressure X-ray photoelectron spectroscopy

2021 ◽  
Author(s):  
David Starr ◽  
Marco Favaro ◽  
Pip Clark ◽  
Rossella Yivlialin ◽  
Maryline Ralaiarisoa ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Liquid Interfaces ◽  
X Ray ◽  
Solid Liquid

scholarly journals Interface Science Using Ambient Pressure Hard X-ray Photoelectron Spectroscopy

Surfaces ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 78-99 ◽  
Author(s):  
Marco Favaro ◽  
Fatwa Abdi ◽  
Ethan Crumlin ◽  
Zhi Liu ◽  
Roel van de Krol ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
General Information ◽  
X Rays ◽  
Tio2 Surface ◽  
Liquid Interfaces ◽  
Experimental Conditions ◽  
Solid Liquid

The development of novel in situ/operando spectroscopic tools has provided the opportunity for a molecular level understanding of solid/liquid interfaces. Ambient pressure photoelectron spectroscopy using hard X-rays is an excellent interface characterization tool, due to its ability to interrogate simultaneously the chemical composition and built-in electrical potentials, in situ. In this work, we briefly describe the “dip and pull” method, which is currently used as a way to investigate in situ solid/liquid interfaces. By simulating photoelectron intensities from a functionalized TiO2 surface buried by a nanometric-thin layer of water, we obtain the optimal photon energy range that provides the greatest sensitivity to the interface. We also study the evolution of the functionalized TiO2 surface chemical composition and correlated band-bending with a change in the electrolyte pH from 7 to 14. Our results provide general information about the optimal experimental conditions for characterizing the solid/liquid interface using the “dip and pull” method, and the unique possibilities offered by this technique.

scholarly journals X-ray Photoelectron Spectroscopy in Mineral Processing Studies

2020 ◽  
Vol 10 (15) ◽  
pp. 5138
Author(s):  
Yuri Mikhlin
Keyword(s):  
Spatial Resolution ◽  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Ambient Pressure ◽  
Surface Characteristics ◽  
Mineral Processing ◽  
Oxidation Products ◽  
X Ray ◽  
Flotation Collectors ◽  
Solid Liquid

Surface phenomena play the crucial role in the behavior of sulfide minerals in mineral processing of base and precious metal ores, including flotation, leaching, and environmental concerns. X-ray photoelectron spectroscopy (XPS) is the main experimental technique for surface characterization at present. However, there exist a number of problems related with complex composition of natural mineral systems, and instability of surface species and mineral/aqueous phase interfaces in the spectrometer vacuum. This overview describes contemporary XPS methods in terms of categorization and quantitative analysis of oxidation products, adsorbates and non-stoichiometric layers of sulfide phases, depth and lateral spatial resolution for minerals and ores under conditions related to mineral processing and hydrometallurgy. Specific practices allowing to preserve volatile species, e.g., elemental sulfur, polysulfide anions and flotation collectors, as well as solid/liquid interfaces are surveyed; in particular, the prospects of ambient pressure XPS and cryo-XPS of fast-frozen wet mineral pastes are discussed. It is also emphasized that further insights into the surface characteristics of individual minerals in technological slurries need new protocols of sample preparation in conjunction with high spatial resolution photoelectron spectroscopy that is still unavailable or unutilized in practice.

scholarly journals In situ X-ray photoelectron spectroscopy of electrochemically active solid-gas and solid-liquid interfaces

2017 ◽  
Vol 221 ◽  
pp. 10-17 ◽  
Author(s):  
Axel Knop-Gericke ◽  
Verena Pfeifer ◽  
Juan-Jesus Velasco-Velez ◽  
Travis Jones ◽  
Rosa Arrigo ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Liquid Interfaces ◽  
X Ray ◽  
Electrochemically Active ◽  
Solid Liquid

scholarly journals Probing Lithium-Ion Battery Electrolytes with Laboratory Near-Ambient Pressure XPS

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1056
Author(s):  
Paul M. Dietrich ◽  
Lydia Gehrlein ◽  
Julia Maibach ◽  
Andreas Thissen
Keyword(s):  
Lithium Ion Battery ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Lithium Ion ◽  
Electrolyte Solutions ◽  
Photoelectron Spectra ◽  
Elevated Pressures ◽  
Ambient Pressure Xps ◽  
Solid Liquid ◽  
Significant Chemical

In this article, we present Near Ambient Pressure (NAP)-X-ray Photoelectron Spectroscopy (XPS) results from model and commercial liquid electrolytes for lithium-ion battery production using an automated laboratory NAP-XPS system. The electrolyte solutions were (i) LiPF6 in EC/DMC (LP30) as a typical commercial battery electrolyte and (ii) LiTFSI in PC as a model electrolyte. We analyzed the LP30 electrolyte solution, first in its vapor and liquid phase to compare individual core-level spectra. In a second step, we immersed a V2O5 crystal as a model cathode material in this LiPF6 solution. Additionally, the LiTFSI electrolyte model system was studied to compare and verify our findings with previous NAP-XPS data. Photoelectron spectra recorded at pressures of 2–10 mbar show significant chemical differences for the different lithium-based electrolytes. We show the enormous potential of laboratory NAP-XPS instruments for investigations of solid-liquid interfaces in electrochemical energy storage systems at elevated pressures and illustrate the simplicity and ease of the used experimental setup (EnviroESCA).

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