Jakob Kibsgaard

Ammonia plays a central role in global fertilizer production and is increasingly recognized as a versatile energy carrier within emerging sustainable energy systems. The La/Co system is an example of an ammonia production catalyst with efficiency greater than that of current commercial catalysts. A spin-mediated promotion mechanism has been proposed as the mechanism behind the catalytic activity. While the resulting catalytic promotion is clearly observed, the change in spin has not yet been directly demonstrated experimentally. In the present study, scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) measurements were performed on a Co(101̅15) crystal and compared with density functional theory (DFT) calculations. The purpose was to obtain an understanding of the properties of the Co(101̅15) crystal surface as a first step to verify the electronic structure changes behind spin promotion. The STM results revealed a stepped surface as expected. A comparison between the STS measurements and DFT calculations indicated that the spin of the Co atoms changes across the surface. This could potentially be caused by adsorbates on the crystal surface or by an interaction between the STM tip and the sample surface.

Electrochemical ethylene oxidation can produce ethylene oxide and ethylene glycol, but selectivity is limited by competition with the oxygen evolution reaction and overoxidation. At the same time, the mechanistic literature is fragmented across oxo-, peroxo-, and hydroxyl-mediated pathways, creating ambiguity and hindering systematic improvement. Using density functional theory (DFT) and scaling relations, we build a unified descriptor-based framework comparing the three pathways across fcc metals, metal(II) oxides, and rutile-structured oxides. The oxygen binding strength is found to control ethylene activation via oxo and peroxo species, while a carbon-based descriptor describes the hydroxyl pathway, and product binding defines an overoxidation limit. The resulting selectivity maps identify the catalyst properties required for each route, rationalize the high performance of individual catalysts such as oxidized Pd, and provide transferable guidelines for designing selective alkene oxidation catalysts.

Asymmetric catalysis underpins pharmaceutical synthesis but is dominated by homogeneousmolecular catalysts that complicate product separation and recycling. Heterogeneousalternatives, including hybrid systems in which molecular catalysts are immobilised on solidsupports, often suffer from diminished activity and poor stability. Here, we use densityfunctional theory and microkinetic modelling to evaluate intrinsically chiral platinum surfacesas a heterogeneous alternative, taking the hydrogenation of hydroxyacetone to 1,2-propanediol (1,2-PD) as a model reaction. On the mirror-image Pt(643)S and Pt(643)ᴿ surfaces,hydroxyacetone chemisorbs at the undercoordinated chiral kink, and the effective transition-state barriers for the two reaction pathways differ by 0.21 eV, favouring S-1,2-PD on Pt(643)S and R-1,2-PD on Pt(643)ᴿ. By contrast, hydroxyacetone is only physisorbed on the achiral Pt(111) terrace and is hydrogenated to a racemic product with a lower effective barrier of 0.75 eV. Microkinetic modelling that accounts for the realistic coexistence of kink and terrace sites identifies an operational window near 500 K and 10⁻² bar in which strong substrate binding at the chiral kink outcompetes the racemic terrace pathway, yielding enantiomeric excesses approaching 99 %. These results establish chiral Pt(643) surfaces as a viable platform for fully heterogeneous asymmetric hydrogenation and motivate experimental verification.

Operando GI WAXS in a flow cell with HOR revealed LiNH ₂ as the only stable crystalline intermediate in the lithium mediated nitrogen reduction reaction (Li-NRR) and the unique solid electrolyte interphase (SEI) formed by diglyme electrolytes.

Manganese dioxide (MnO2) has been reported as a potential electrocatalyst for the oxygen evolution reaction (OER). Despite prior reports demonstrating promising activity for OER in acidic media, its stability in acidic conditions remains insufficiently understood. In particular, the stability of electrodeposited MnO2 layers remains unknown. Herein we correlate in-situ electrochemical liquid phase transmission electron microscopy (ec-LPTEM) to operando electrochemical techniques to investigate the debated existence of a stable potential regime for OER operation with electrodeposited ε-MnO2 at pH 1. To this effect, the growth of this catalyst is conducted in-situ by electrodeposition inside the microscope and its dissolution is subsequently demonstrated upon acidification of the electrolyte. Operando scanning flow cell – inductively coupled plasma mass spectrometry results corroborate the MnO2 dissolution at open circuit potential and indicate a < 100 mV window of stability of the material between ~1.50-1.55 VRHE at pH 1. Furthermore, measurements of oxygen gas in operando conditions establish that the onset of oxygen evolution reaction occurs outside this window of stability. Such combination of in-situ ec-LPTEM, identical location and operando electrochemical techniques provide key insights into the opportunities and limitations of electrodeposited ε-MnO2 for OER under acidic conditions.

Non-aqueous electrolytes offer significant advantages in electrochemical systems by mitigating hydrogen evolution reaction selectivity issues. Thus, they show promise for applications such as lithium- or calcium-mediated nitrogen reduction [1, 2] and carbon dioxide electrolysis [3]. However, sustaining these systems requires a viable anodic process, such as the hydrogen oxidation reaction, which remains underexplored in non-aqueous media. A few studies exist in solvents like acetonitrile and tetrahydrofuran [4,5,6], but each non-aqueous solvent behaves differently, and the proton mediation pathways remain to be determined. Conclusive findings are challenging due to the presence of water impurities, impurities associated with solvent synthesis, and electrolyte transformations that limit the duration and charge range of experiments. In this study, we address these challenges and investigate hydrogen oxidation in diglyme, tetrahydrofuran, propylene carbonate, and ethanol using cyclic voltammetry on polycrystalline platinum with a rotating disk electrode. Lithium tetrafluoroborate is used as the supporting electrolyte, and we additionally examine the effects of water and ethanol as potential proton mediators. Ferrocene is used to calibrate the reference potential against the standard hydrogen electrode for each solvent. The hydrogen oxidation reaction activity shows a strong dependence on the electrolyte medium, highlighting distinct solvent-specific behaviors. Water and ethanol addition markedly influence the proton mediation process, with effects varying based on the amount of charge passed. These findings emphasize the importance of solvent choice and proton mediators in enabling robust hydrogen oxidation reaction performance for sustainable non-aqueous electrochemical systems. References Li, S. et al. Nature 629, 92–97 (2024) Fu, X. et al. Nat. Mater. 23, 101–107 (2024) Kuntyi, O. et al. J. Chem. 2022, 1–12 (2022) Ledezma-Yanez, I. et al. ChemElectroChem 2, 1612–1622 (2015) Suárez-Herrera, M. F. et al. Langmuir 28, 5286–5294 (2012) Hodgetts, R. Y. et al. ACS Catal. 12, 5231–5246 (2022)