Csaba Janáky

Pairing the carbon dioxide reduction process with the electrocatalytic oxidation of glycerol (GOR), instead of the typically applied oxygen evolution reaction, can substantially decrease the cell voltage while forming high-value products at both electrodes. In this contribution, glycerol oxidation was driven as the anode process of a CO2 electrolyzer cell employing different metal (Fe, Ni, and FeNi)-containing nitrogen-doped carbon single-atom catalysts. Under optimal conditions, GOR was sustained at industrially relevant reaction rates (above 100 mA cm–2 current density) with above 90% Faradaic efficiency toward formate formation. At identical total metal loading, the bimetallic FeNi-NC reached around 35–40% higher GOR activity and stability (more than 5 h) under industrially relevant conditions compared to its monometallic counterparts. We demonstrated that a considerable decrease in the metal loading can be achieved by employing single-atom catalysts instead of nanoparticulate catalysts to drive the GOR without sacrificing activity, selectivity, and long-term stability. Our results could serve as a stable foundation in designing future GOR catalysts that could be readily applied as anodes in CO2 electrolyzer cells.

Recent scientific advancements indicate that the electrochemical reduction of carbon dioxide to carbon monoxide (CO2RR) is approaching industrial viability. Beyond scientific achievements, technology scale-up requires a full understanding of how certain cell components are to be used for long-term optimal performance and of what other challenges are posed by the larger sizes. Here, we investigated in detail how varying the compression ratio of the cathode gas diffusion electrode affects the electrochemical performance, using three fundamentally different carbon-based cathode supports. Electrochemical impedance spectroscopy and microtomography measurements are presented to explain the observed changes in the electrolysis performance, while the cathodes were gradually compressed to below 40% of their original thickness. The optimal compression range depends on the properties of the gas diffusion layer. Notably, a more than 100 μm wide optimal compression range is found for the thick ELAT1400W gas diffusion layer (i.e., a compression to 60-85% of its original thickness), which is further confirmed in 100-h-long experiments.

Low-temperature CO₂ electroreduction (CO₂eR) to syngas offers tunable H₂:CO ratios and a renewable route to decarbonized syngas production, yet catalyst-level advances rarely translate to scalable, durable systems. This review addresses that disconnect with a systems-engineering perspective. We first establish the component foundations, electrolytes, membranes, and cell architectures of flow cells and zero-gap membrane electrode assembly (MEA) electrolyzers, together with integrated versus decoupled syngas production modes, then analyze the engineering failure modes that dominate at scale: non-uniform current distribution, localized hotspots, electrode flooding, salt precipitation, and thermal gradients. Single-pass CO₂ conversion efficiency (SPCE) is introduced as a co-equal metric alongside Faradaic and energy efficiency (FE/EE). Original contributions include a standardized accelerated stress test (AST) protocol, a lifecycle sustainability assessment (LCSA) framework with quantitative carbon footprint benchmarking, a mitigation strategy compatibility matrix, and three-benchmark design pathways targeting high EE, high stability, and high SPCE, providing an actionable systems-engineering roadmap toward CO₂eR systems sustaining >5000 h at industrially relevant current densities.

CO ₂ electrolysis is an emerging technology for the sustainable production of fuels and chemicals. Its transition from laboratory‐scale research to real‐world application is strongly driven by both regulatory and strategic means, aimed at achieving net‐zero greenhouse gas emissions. To meet this goal, accelerated progress in CO ₂ electrolysis research and technological development is essential to ensure economic viability. This requires clear performance targets, reference materials, and standardized testing protocols that serve as a basis for reliable performance comparison within the CO ₂ electrolysis community. To address this need, a Round Robin experiment was conducted involving well‐established R&D entities in the field of CO ₂ electrolysis. The objective was to identify and mitigate the main sources of experimental variability, thereby enhancing reproducibility. We found that especially the modes of temperature measurements and cell/anolyte heating alongside pressure fluctuations and overpressures during product analysis are considerable differences among labs, while adjustments to the initial electrochemical protocol helped in minimizing voltage spikes in changing operation. As a result of multiple measurement campaigns and in‐depth discussions among participants, a recommendation for a standardized testing protocol and test setup requirements for CO ₂ electrolyzers are provided.

Carbazole derivatives, such as MeO-2PACz and 2PACz are known to improve the performance of halide perovskite solar cells by facilitating hole transfer. To assess their interaction with halide perovskites, we probed the hole transfer from excited CsPbBr₃ quantum dots to MeO-2PACz and 2PACz using emission spectroscopic and transient absorption techniques. The different oxidation potentials of these two carbazoles result in divergent interactions with CsPbBr₃ QDs. Whereas MeO-2PACz quenches the emission of CsPbBr₃ QDs, 2PACz enhances the emission by remediating the surface traps. Transient absorption studies confirm the formation of MeO-2PACz^+• cation radical with characteristic absorption in the near IR region. No such oxidation process was observed with 2PACz. The mechanistic insights into the interaction of the two carbazole derivatives with excited perovskite nanocrystals will add another piece to the untold story behind the improved performance of perovskite photovoltaic devices.

Iridium is one of the most frequently employed anode electrocatalysts in CO₂ and CO electrolysis, thanks to its reasonable overpotential for the oxygen evolution reaction (OER) and high stability under operating conditions. The latter has been challenged recently by a handful of studies where destabilization of iridium was observed, which was explained solely by thermodynamics (iridium is unstable at strong alkaline pH and OER potentials). In this study, we demonstrate that liquid CO and CO₂ electrolysis products (such as ethanol and acetate) crossing over to the anode side under long-term operation have a severe effect on the stability of iridium. Its dissolution was studied by both ex-situ inductively coupled plasma mass spectrometry (ICP-MS) and in situ (online ICP-MS) techniques. Based on our electrolysis experiments carried out in a broad pH range (pH = 4-14), ethanol, and its partially oxidized counterpart, acetaldehyde, decreases the stability of the anode catalyst. Ethanol/acetaldehyde oxidation competes with the OER and starts in conjunction with the surface oxidation of the Ir catalyst particles. The oxygenated species are consumed by the alcohol/aldehyde oxidation process, preventing the formation of a passivating surface oxide layer, resulting in an increased iridium dissolution rate.

As CO₂ electrolysis emerges as a key technology for industrial decarbonization, scaling from lab to industrial systems introduces challenges beyond increasing the active area or the CO₂ feed rate. Larger reactors often exhibit spatial inhomogeneities in selectivity and current density, issues overlooked in conventional performance studies. To address this, we designed, built, and tested a zero-gap flow cell for CO₂ electrolysis that enables local monitoring of the product selectivity and current density. Gas composition is sampled at multiple points along the flow path, while current density is tracked across the cell. This approach reveals where and under what conditions parasitic hydrogen evolution occurs. In this work we present how operating parameters influence localized product formation and current density profiles in a CO₂-to-CO electrolyzer. Our findings emphasize the importance of moving beyond averaged metrics to achieve efficient, uniform operation across the cell, an essential step for successful scale-up.

Microporous-layer-free cathodes deliver high-rate, durable CO ₂ electrolysis, challenging conventional electrode design principles and simplifying device architecture.