The development of rechargeable batteries can be accelerated by the fundamental understanding of their chemistries. Multiple characterization techniques have been deployed to study the chemical processes in batteries, but structural studies at the atomic level using X-ray diffraction (XRD) and total X-ray scattering (TXS) show enduring popularity. These methods are relatively easy to apply in operando mode, where structural data is collected alongside electrochemical data under operating conditions. With a growing interest in this powerful methodology, it is important to review the general principles of operando XRD/TXS characterization and develop a set of guidelines for the collection, analysis, and presentation of data that are acceptable to the community and can lead to reliable, representative, and reproducible results that are easy to judge and compare. This Review aims to survey and discuss important steps in operando XRD and TXS. From cell and electrode design to data treatment, we survey the major experimental aspects of operando studies, pointing out potential pitfalls and identifying best-practice. In addition, in the present review, the researchers from UiO conducted some unconventional experiments in operando mode to illustrate how such methods can be used beyond studies of the early-stage cycling mechanisms of battery active materials.
Highlighted publications
The conversion of CO2 into energy-dense liquid fuels, such as methanol, represents a cornerstone of sustainable chemistry; however, most homogeneous catalytic systems still rely on noble metals or Lewis acid additives. Here, we report the first protocol for amine-assisted CO2 hydrogenation to methanol using a Mn–MACHO catalyst without any Lewis acid co-catalyst, achieving turnover numbers up to 45.2, the highest reported for Mn systems. A combined computational, microkinetic, and experimental study reveals that diamines dramatically enhance activity compared to monoamines by promoting a highly exergonic double amidation step. This thermodynamic driving force shifts the equilibrium away from formate resting states toward the active catalyst, thereby accelerating methanol formation. The correlation established between amidation free energies and methanol productivity provides a rational design principle for tailoring amine promoters across Ru- and Mn-based MACHO catalysts. These insights advance the development of sustainable, base-metal-catalyzed CO2 conversion strategies and open opportunities for integrated carbon capture and utilization.
Nickel provides essential catalytic properties for hydrogen electrodes in proton-conducting ceramic electrochemical cells. However, Ni diminishes the hydration capability and proton conductivity when incorporated into electrolyte materials including BaZr0.8Yb0.2O3−δ studied here. Through semiquantitative atomic-resolution scanning transmission electron microscopy, density functional theory simulations, X-ray total scattering, and absorption spectroscopy, we reveal that Ni forms point defect clusters with the Yb acceptors wherein oxygen vacancies are trapped and resist hydration. The resulting effective acceptor concentration is described by point defect reactions in quantitative agreement with thermogravimetric measurements of hydration for samples substituted with 2–5 mol % Ni by BaNiO2 addition. Moreover, excess B-site cations due to NiO addition induce the formation of antiphase boundaries (APBs) that are enriched in Yb and thereby deplete the bulk of acceptors, further suppressing hydration. The adverse effects of Ni are thereby resolved into two novel mechanisms, opening new avenues in point defect engineering for high-performance electrolytes.
X-ray diffraction is extremely powerful to study the structure of well-ordered, crystalline materials. In this paper, researchers from the Catalysis Section, NAFUMA, the Swiss Norwegian Beamlines, and Haldor Topsoe A/S take it one step further, by developing models for advanced diffraction studies of a disordered material, namely the beta zeolite. Despite the tremendous structural complexity caused by the disorder, these new models make it possible to resolve the degree of deactivation of the zeolite catalyst from a single diffractogram.
In-situ TEM experiments shows that the tendency for elemental mixing- or segregation to occur in Pt–Rh nanoparticles depends on the nanoparticle size and temperature. The smaller nanoparticles (≲13 nm) are stable in the solid solution configuration over the entire studied temperature range. Larger nanoparticles (≳13 nm) tends to segregate when cooled to room temperature. The results are of importance to understand the thermodynamics of this specific Pt–Rh nanoparticle system and it add value towards applications like catalysis, whereof e.g. supported Pt–Rh nanoparticles are attractive candidates for NH3 slip abatement processes.
New chemical transformations can be catalyzed with molecular gold compounds or gold nanoparticles. Researchers at the catalysis group have reported a simple and robust protocol for the synthesis of gold(III) compounds that are crucial for the development of these catalytic reactions. The synthesis utilizes heating in a microwave oven, and produces a number of new compounds, quickly and cleanly, in a one-step process.
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Dense ceramic oxygen transport membranes (OTMs) combining high oxygen flux with chemical and mechanical stability find numerous applications in industrial processes where oxygen is extracted from air. In the present publication, Sintef Industry and The Electrochemistry group at SMN have collaborated in a project financed by the Research Council of Norway (CLIMIT 268450) rationalizing the performance limitation of OTMs based on state-of-the-art ceramic composite system.
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Heterogeneous catalysis is a key enabling technology for the transition from a fossil-based society to a renewables-based scenario. Industrial catalysts are always shaped into millimeter-sized catalyst objects suitable for large scale industrial use. However, these catalysts invariably suffer from a loss of performance due to carbon deposits. It is vital to understand how these phenomena occur in these shaped objects, resolved both in time and space.
Joint research between the University of Oslo and Pennsylvania State University resulted in the development of a toolset necessary to understand the chemical changes in amorphous battery materials at atomistic level. This work has been recently published at Chemistry of Materials and has been selected for a cover page of the corresponding issue.
Nanocomposite materials consist of nanometer-sized quantum objects such as atoms, molecules, voids or nanoparticles embedded in a host material. These quantum objects can be exploited as a superstructure, which can be designed to create material properties targeted for specific applications.