Inspiring Plenary Lectures by International Experts

Electrochemistry is central to achieving a net-zero society. While fuel cells and batteries are crucial for decarbonising transport, electrolysers offer a sustainable route to producing fuels and chemicals, such as hydrogen and ammonia. Intriguingly, many electrochemical reactions we aim to accelerate in electrosynthesis—such as hydrogen evolution in water electrolysis—are exactly those we strive to suppress in batteries and nitrogen reduction. This talk will explore how insights from electrocatalysis inform battery science and vice versa. 

I will present mechanistic studies on (i) oxygen evolution in iridium-based catalysts for water electrolysis, (ii) nitrogen reduction to ammonia in organic electrolytes, and (iii) parasitic gas evolution in lithium-ion batteries. These studies integrate electrochemical mass spectrometry, operando optical spectroscopy, cryo-electron microscopy, secondary ion mass spectrometry, X-ray photoelectron spectroscopy, and density functional theory. By combining these techniques, we develop a holistic understanding of the factors governing these technologically critical reactions. 

Battery technology has enabled large scale mobility, mobile equipment and stabilizing the grid on short timescales. Yet there is much to wish for, larger energy densities are required to extend driving range for instance, improved safety is paramount with the scale that batteries are being introduced i0n our daily lives, use of abundant and less critical raw materials, and as well as more sustainable processes are demanded. More battery chemistries enter the market and countless battery chemistries are being explored addressing one or more of these wishes. All these current and future battery generations/chemistries have one common challenge, reversibility. Extremely high reversibility is demanded to reach thousands of charge-discharge cycles, a prerequisite to arrive at acceptable battery cost and environmental impact. In this talk we look at what processes challenge the reversibility in some of the next generation high energy density battery chemistries, specifically focussing on the atomic scale design and development of electrolytes to improve this.    

The interplay between the electrode surface, water, and ions at the electrode-electrolyte interface is a key factor in the performance of electrolyzers. Here, I will discuss our efforts to understand this interfacial chemistry using X-ray spectroscopy. To this end, we have designed operando X-ray photoelectron spectroscopy and (soft) X-ray absorption spectroscopy methodology that can specifically detect the individual chemistries of interfacial water, near-surface ions, and the electrode surface. Here, I will discuss case studies from both alkaline and acidic electrolysis, in which we investigated electrolyte effects and electrode restructuring. 

1Chemical Technology III, Faculty of Chemistry and CENIDE; University of Duisburg-Essen, Carl-Benz-Straße199, 47057 Duisburg/Germany 

Catalyst materials play an important role in enabling sustainable hydrogen production via water electrolysis. Catalyst materials can be complex in structure, often having various crystal orientations. Their effectiveness is usually tested using catalyst films, which give an average performance across all structural features. Therefore, it’s important to understand how structure relates to activity at the catalyst level to design better electrocatalyst materials. At the device level, complexity increases because the catalyst and other parts like membranes, ionomers, and operation modes can affect stability and long-term performance.  

This talk will show examples of how scanning electrochemical cell microscopy (SECCM) enables the evaluation of oxygen evolution reactions (OER) catalysts at the nanoscale. I will point out key factors to be considered when testing OER catalysts with SECCM, focusing on how the atmosphere used during measurements affects the recorded activity. In the second part, I will discuss how the composition of the electrolyte and the operation mode influence the stability of low-temperature anion-exchange membrane electrolysis. 

Acknowledgment: The financial support was provided by the German Research Foundation (Deutsche Forschungsgemeinschat, DFG) – CRC247 [388390466] and BMBF – project PrometH2eus (03HY105F).  

CO2 electrolysis to fuels or commodity chemicals, driven by renewable energy, provides a unique opportunity to both utilize CO2 and store renewable energy in chemical bonds [1]. The CO2 feedstock for the CO2 electrolysis can be obtained from various sources, such as from direct air capture (DAC) or from point sources such as the chemical industry or power plants. One of the major drawbacks of using industrial CO2 point sources is the presence of contaminants such as SO2, H2S, COS, NOx and other volatile organic compounds that could be highly detrimental to the catalysts that drive the conversion of CO2 to products.

In this talk, I will discuss the influence of various concentrations of sulphur-based gaseous impurities, specifically SO2, H2S and COS, on the selectivity, product distribution and catalyst stability during CO2 electrolysis. First, I will show the effect of SO2 impurities on the electrocatalytic performance of a N-doped carbon catalyst for CO production. Overall, this study demonstrates the strong tolerance and robustness of N-doped carbon catalysts compared to silver for the reduction of CO2 to CO in the presence of SO2 impurities. Finally, I will show that SO2, H2S and COS contaminants significantly suppress the formation of hydrocarbon products during the CO2RR on copper-based electrodes, both at low currents in a H-cell setup and at higher currents in a GDE flow cell. I will show that the suppression is related to the type of contaminant, its concentration, the cathode potential and the cell configuration. Moreover, I will provide insights on the degradation pathways and highlight the importance of these results for the design of large-scale processes that convert CO2 feeds with these impurities.

Mariana Monteiro 

Interface Science Department, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany 

Acidic electrochemical CO2 reduction offers a promising method to convert CO2 into valuable chemicals and fuels, providing advantages over neutral or alkaline systems, such as lower energy consumption and higher carbon utilization. Despite these benefits, the optimal electrolyte for acidic media remains unclear. Key challenges include ensuring catalyst stability and optimizing operating conditions, like current density and pH, to maximize efficiency and product yield. In this study, we explore CO2 reduction on copper in seven different acidic electrolytes. We investigate the impact of supporting anions and their solution chemistry on reaction selectivity across current densities of 10–160 mA/cm². The catalyst’s chemical state and evolution are monitored using operando X-ray Absorption Spectroscopy (XAS), while morphological changes are analyzed via Scanning Electron Microscopy (SEM). Our results show that selectivity correlates with the pKa and diffusion coefficient of the acids, affecting local pH and determining optimal operating currents for each electrolyte. In contrast, morphological and chemical state changes seem to play a less significant role. Finally, we provide guidelines for selecting electrolytes in low-pH CO2 electrolysis, which is crucial for advancing acidic CO2 reduction technologies. 

In this contribution I will discuss the state-of-the art and challenges yet to be met in material and interface science for the next-generation EV batteries. Next to the challenge of sustainability in material supply chain, manufacturing line and recycling prospects, the development of next-generation Li-ion batteries (LiBs) requires understanding and control over interface reactions that drive both the operation and degradation of the battery. To this purpose, I will introduce and reflect on the merits and opportunities offered by gas phase deposition technologies, such as atomic layer deposition (ALD), towards electrochemically and mechanically stable electrode/electrolyte interfaces. ALD delivers uniform and conformal thin films with ultimate control over thickness and chemical composition, with major opportunities for processing also on complex, 3D electrode structures. This contribution will encompass several examples of interface engineering by ALD, ranging from LiF to Li2CO3 and N-doped Li3PO4, while providing thoughts on them challenges towards implementation of ALD in a battery manufacturing line, in terms of added (manufacturing) costs vs. added value (e.g., impact on KPIs). 

Formation of intermediates and degradation products, ion transport and crossover of active species through membranes are all important processes synergistically affect the performance of a redox flow battery. I will present how we couple nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) to probe these processes in operando. NMR and EPR are non-invasive, atom-specific, quantitative and complementary to one another – the former detecting diamagnetic species and the latter paramagnetic species. Using anthraquinone and viologen-based RFBs as examples, I will demonstrate the detection and quantification of radical intermediates and degradation products. I will show how the electronic structures of the radicals can be revealed through the analysis of the hyperfine coupling features of the EPR spectra. Furthermore, lithium ion transport through the membranes, as a function of charge-discharge cycles, can be captured and quantified, as well as the crossover of the redox-active species. Simultaneously, I will demonstrate that compact and low-cost benchtop NMR and EPR systems have sufficient spectroscopic resolution and sensitivity to perform these mechanistic studies, with the hope of increasing the accessibility to a broader electrochemistry community.         

Electrolysis is at the core of Power-to-X (P2X) technologies, enabling the conversion of renewable electricity into fuels and chemicals. Among electrolysis technologies, Solid Oxide Electrolysis Cells (SOECs) and Proton-Conducting Electrolysis Cells (PCECs) stand out for their high efficiency, benefiting from favorable thermodynamics and reaction kinetics at elevated temperatures. A key advantage of these technologies is their reliance on scalable, non-precious materials such as nickel, zirconia, and steel, making them cost-competitive. While SOECs are relatively mature and widely used for the co-electrolysis of CO₂ and H₂O to produce syngas (CO and H₂), PCECs offer a unique advantage by operating at lower temperatures, facilitating the direct production of methane (CH₄), higher hydrocarbons (C₂, C₃), and alcohols. These emerging technologies hold significant potential for enabling carbon-neutral energy cycles and expanding P2X applications. 

Despite their promise, SOECs and PCECs face critical degradation challenges that hinder commercialization. SOEC degradation primarily occurs at the stack level, requiring improvements in interconnect coatings, contact materials, and thermal stability. PCECs, still in an earlier stage of development, suffer from single-cell degradation issues, including electrode sintering, proton transport limitations, and chemical instability under CO₂/H₂O electrolysis conditions. In this contribution, we will explore advancements in materials, novel cell architectures, and innovative operation modes—such as coupling with thermal catalysis and plasma activation—aimed at enhancing SOEC and PCEC performance and accelerating their commercial viability. 

Chemical energy storage is the transformation of electrical power into chemical energy carriers, allowing grid flexibility by backing up intermittent electricity of renewable energy sources. Once the excess renewable energy is stored into chemical bonds, several pathways are opened for both re-electrification and mobility. For such storage, efficient technologies for electrosynthesis of chemicals and fuels are critical for a carbon-free energy future. Here, I will discuss about the generation and simultaneous conversion of green hydrogen in oxide ion- and proton- conducting ceramic cells, operating at intermediate and high temperatures. I will focus on rationally designed, nanoengineered mixed ionic-electronic conducting electrocatalysts, prepared by redox exsolution that allow promising performance and stability in harsh environments. The proposed approaches aim to bridge electrochemistry and heterogeneous catalysis, while exemplifying a route for enabling electrosynthesis at industrially relevant temperatures.  

This lecture delves into the fundamental principles underlying the electrochemical reduction of carbon dioxide (CO2RR) and its interaction with the hydrogen evolution reaction (HER). Our focus is on our group’s extensive exploration of CO2RR on copper electrodes in organic solvents. 

Utilizing online gas chromatography and in situ FTIR spectroscopy, our findings underscore the significant impact of electrode morphology and solvent composition on this reaction. Notably, in solvents such as acetonitrile, our analyses reveal the critical role of water content at the solid-liquid interface in determining reaction selectivity. We also demonstrate that the CO2 reduction reaction competes with HER under these conditions. 

Building on prior observations in aqueous solvents, our study elucidates the decisive influence of alkyl cation length—commonly used as an electrolyte in organic solvents—on the reaction mechanism. Specifically, our data show that smaller cations (TEA) promote the formation of oxalic acid, while larger cations (TBA) favor the production of carbon monoxide. 

Moreover, we investigated the impact of amine solvents on carbon capture and utilization in a direct process. Our in situ spectroscopic analysis indicates that the steric effects of amines and their interactions with the electrode surface significantly influence product distribution during CO2RR. 

This lecture will leverage advanced in situ spectroscopic techniques and DFT calculations to elucidate the complex mechanisms behind these reactions and highlight the pivotal role of the cation in determining product distribution. 

The electrocatalytic conversion of CO₂ to hydrocarbons using renewable energy offers a sustainable pathway for producing carbon-neutral fuels and value-added chemicals.1 However, a major challenge remains in developing efficient and robust electrocatalysts with high selectivity for a single product at low overpotential and long stability.1 Here, we report the use of molecular additives electrodeposited on heterogeneous electrodes to fine-tune the microenvironment of active sites. These hybrid electrodes exhibit superior selectivity, activity, and stability compared to their pristine counterparts under similar conditions.2 We identified multiple roles of the organic coating, including nanostructuring and stabilizing metallic electrodes during catalysis, stabilizing key intermediates, forming hydrophobic layers, and/or serving as active catalytic sites.3-5 We demonstrate that this approach is versatile across various systems and holds significant promise for advancing next generation electrolyzers. 

(1)  Z. Sun et al. Chem 2017, 3, 560–587.
(2) D.-H. Nam et al. Nat. Mater., 2020, 19, 266–276.
(3) A. Thevenon et al. Chem. Int. Ed. 2019, 18, 58 (47) 16952
(4) F. Li et al. Nature, 2020, 577, 509-513
(5) A. Thevenon et al. ACS Catal. 2021, 11, 8, 4530–4537 

Alexander Bagger  Technical University of Denmark, Department of Physics

I will discuss how experiments and computational simulations can support each other. I will focus on electrochemical reduction of NOx, CO2, N2, and the combinations. Importantly, all these reactions share a direct competition with hydrogen, and furthermore, several products are formed from each reactant of these reactants. I will give minimalistic models that do not overfit or over interpretating experimental data: 

1. eCO2 reduction show multiple different products depending on metal catalyst1,2 
2. eNOx reduction produce N2O, N2 and NH33,4. Interestingly, reactive metals work close to their reduction potential5-6. 
3. eN2 reduction to NH3 at ambient conditions has been confirmed on a Li-mediate system7. I will discuss systems beyond lithium8. 
4. Finally, I will show predictive schemes for the synthesis of urea9,10. 

[1] Hori et. al., J. Chem. Soc., Faraday Trans., 1989. 
[2] Bagger et. al., ChemPhysChem, 2017.
[3] Rosca, Duca, Groot, Koper, Chem. Rev. 2009.
[4] Wan, Bagger, Rossmeisl, Angew. Chem., 2021.
[5] Carvalho, …, Stoerzinger, JACS 2022.
[6] Riyaz, Bagger, Electrochim. Acta. 2025.
[7] Tsuneto et al. JEAC. 1994.
[8] Bagger, et. al., ACS Energy Letters. 2024.
[9] Wan, …, Bagger, ACS Catalysis, 2023.
[10] Wuttke, Bagger, Commun. Chem. 2025. 

Integrating the electrooxidation of an organic compound, such as an alcohol, in a water electrolyzer is a promising strategy for saving energy during hydrogen production while forming value-added products at the anode. This approach is known as hybrid water electrolysis (HWE). In this contribution, the concept of “energy saving” in HWE is illustrated by comparing the performance of a series of LaFe1xCoxO3 perovskites towards the oxygen evolution, and the electrooxidation of glycerol and isopropanol.[1] As a second example, the influence of various operating conditions, including electrode potential and electrolyte composition, on the performance of Ni oxide nanoparticles towards the electrooxidation of glycerol is discussed.[2] The results shown here illustrate the trade-off between activity and selectivity in HWE, and highlight the need for identifying suitable catalysts and electrolysis conditions to minimize this trade-off.[3] 

References: [1] A.C. Brix, et al. ChemElectroChem 9 (2021) e202200092 [2] D.M. Morales, et al. ACS Catalysis 12 (2022) 982-992 [3] F.J.A. van Lieshout & D.M. Morales, ChemPlusChem 89 (2024) e202400182.