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.

ABSTRACT 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.

CO2 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 CO2 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 CO2 electrolysis community. To address this need, a Round Robin experiment was conducted involving well-established R&D entities in the field of CO2 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 CO2 electrolyzers are provided.

Photoelectrochemistry provides a direct route to convert sunlight into valuable chemicals. However, high-performance photoelectrode architectures often require complicated synthesis steps and expensive instrumentation. Although physical immobilization (e.g., spray coating) of catalyst particles on semiconductors seems to be a simple and universal approach, it is rarely implemented to prepare photoelectrodes. Here, we highlight challenges associated with such deposition strategies and demonstrate the importance of rational photoelectrode design. Specifically, we introduce metal interlayers (Pd, Au, or Ni) between n-type Si and a spray-coated PdAu catalyst. We show that these interlayers are essential for generating photopotential at the interface, while the PdAu catalyst governs C3 selectivity during glycerol oxidation. We also demonstrate that the interlayer determines key performance metrics (e.g., photopotential, photocurrent density, and stability). With this approach, the best-performing PdAu/Au/Si and PdAu/Ni/Si photoelectrodes can deliver high reaction rates (>100 mA cm-2) with sufficient stability even at higher illumination intensities (50 suns).

Molybdenum disulfide (MoS2) has emerged as a promising alternative to platinum‐based catalysts for the hydrogen evolution reaction (HER) at the cathode in PEM water electrolyzers. In this study, we report the development of large‐area, binder‐free MoS2 electrocatalyst cathode synthesized via in‐situ hydrothermal growth on carbon cloth substrates, eliminating the need for binders and post‐synthesis processing, while enabling the formation of edge‐enriched MoS2 nanosheets with abundant active sites. PEM cells with cathodes of on‐collector grown vertically aligned MoS2 nanosheets (at 3 and 7 mg cm−2 loadings over 9.6 cm2 area) could deliver a current density of 200 mA cm−2 at voltages as low as 2.09 and 1.94 V under ambient conditions. Chronoamperometric stability tests indicate gradual reduction of cell current (e.g., to ∼76% and ∼52% of the starting value in 1 and 8 h, at a catalyst loading of 3 mg cm−2) due to partial pitting and loss of the catalyst in microscopic patches from the carbon cloth, the excellent Faradaic efficiency (near 100%) and competitive overall HER activity of MoS2 grown hydrothermally directly on the current collector holds promise of the technology for scalable and sustainable PEM water electrolyzer systems provided the support–catalyst interaction is optimized further.

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.

One of the key challenges in the mid-21st century is maintaining economic growth while ensuring environmental sustainability. The European Green Deal aims to tackle this challenge by striving to make Europe climate-neutral by 2050. A promising approach to support this goal is the conversion of carbon dioxide, a major greenhouse gas, into valuable products such as energy carriers, fine chemicals, and pharmaceuticals. This process can be carried out in an environmentally and economically sustainable way through the use of renewable energy sources with the appropriate technologies. The direct electrochemical reduction of carbon dioxide into carbon monoxide (a valuable product that can be seamlessly integrated into the currently available chemical value chain) represents a promising waste-to-wealth strategy among existing technologies. This process can be effectively paired with carbon-free electricity sources, ensuring complete sustainability. To achieve economically viable performance, advancements in novel catalysts and cell designs are essential, alongside the development of technological solutions that enable scaling up to industrially relevant levels. Zero-gap electrolyzer cell technology achieves high reaction rates and efficiencies under ambient or near-ambient conditions. Additionally, its operation is simpler compared to other carbon dioxide electrolyzer technologies (for example, precise pressure control is not required since there is no flowing catholyte within the cell), which facilitates scaling up these systems. Many research groups are studying the fundamental chemistry of zero-gap electrochemical cells, typically using small experimental test cells. While these studies provide valuable scientific insights (such as the selection of appropriate catalysts, components, and understanding long-term degradation) the small scale of these test cells represents only a "single-point" chemistry compared to industrial-scale electrolyzers. Careful consideration is needed when scaling up, as several additional challenges arise, primarily of mechanical nature. These challenges can create uneven conditions across the cell and the electrochemically active area, significantly influencing the electrochemical processes in specific sections. Over the past several years, we have successfully scaled up electrochemical cells for CO 2 -to-CO conversion, progressing from small experimental test cells (8 cm 2 ) to industrial-scale cell stacks (2500 cm 2 per cell). Throughout this development journey we encountered many of the challenges outlined above. In this talk, I will discuss some of these challenges, their origins, their impacts, and the factors influencing them, as well as the key principles and strategies that can be applied to find solutions.

By today, we can all feel the effects of global warming on our skin. “Intervention is needed, and it is needed now” – said by Richard Jones, co-founder of eChemicles Inc. The transition to a sustainable energy landscape requires innovative solutions for the utilisation of carbon dioxide (CO 2 ). Our response at eChemicles Inc. is to develop a disruptive low-temperature electrolysis technology that converts CO 2 into valuable chemicals and fuels. Electrochemical reduction of CO 2 offers the dual benefit of reducing carbon emissions while producing useful products. However, current electrochemical CO 2 reduction technologies often face limitations in energy efficiency or in selectivity of useful products. Low-temperature CO 2 electrolyzers operate at moderate temperatures and pressures, and with appropriate cell design, they are suitable for dynamic operation and integration with intermittent renewable energy sources. Zero-gap type electrolyzer cell design is one such example; cells and cell stacks designed in this way are capable of converting CO 2 into useful products for the chemical industry with high selectivity and industrially relevant current densities at low cell voltages, resulting in high energy efficiency (e.g. into carbon monoxide (CO), which can be used as a chemical raw material or in the form of syngas for production of eFuels and eChemicals). During scale-up, technologies similar to zero-gap CO 2 electrolyzers - such as water electrolyzer cells or fuel cells - can be integrated in an appropriate way: the solutions, experience, and production lines have been proven that there can be a significant advantage in the development process. After careful evaluation of component availability and machining capacity we scaled up our single electrolyzer cell from a geometric area of 8 cm 2 to 2500 cm 2 in two steps. A further increase in electrolyzer capacity was achieved by stacking these quarter square meter (QSM) cells. Our CFD-assisted design allows up to 100 cells to be stacked in a single unit. As part of a system design to demonstrate the technology (TRL6), a containerised unit with a CO production capacity of 100 tonnes of CO per year was designed, built and commissioned. In a feasibility study for plants with CO conversion capacities of 20 and 200 tonnes per day, we answered engineering questions ranging from the selection of system components to a 3D layout design. Innovations in catalysts, cell design, and system integration are essential. Collaborations between academia, industry, and policymakers are vital for realizing large-scale CO 2 electrolysis. Scaling up low-temperature CO 2 electrolysis requires concerted efforts to enhance performance, stability, and economic viability. By addressing technical challenges, we are paving the way for sustainable carbon utilization on an industrial scale.

Photoelectrochemistry holds the promise of directly converting sunlight into valuable chemical products by combining the functions of solar panels and electrolyzers in one technology. Photoelectrochemical (PEC) methods, however, lag behind their electrochemical counterparts in terms of current density. In the first part of my talk, I will demonstrate that by using concentrated sunlight and continuous flow PEC cell, we can achieve current densities similar to electrochemical methods (>100 mA cm –2 ), but with significantly lower energy input. In addition, I will show that the product distribution of glycerol oxidation is notably different in PEC and electrochemical scenarios at the same current density, and the parasitic oxygen evolution reaction can be suppressed in the PEC case. In the second part of my talk, I will reveal the importance of catalyst choice to further decrease the energy requirement (i.e. the cell voltage) of the paired conversion of glycerol and water. Moreover, I will demonstrate that the catalyst choice also dictates the product distribution and enables the selective production of C3, C2 or C1 glycerol oxidation products. Finally, I will show that by properly considering thermodynamic and kinetic aspects, there is a possibility for bias free (standalone) operation at high current density (>30 mA cm –2 ) even using low bandgap Si which alone can supply the necessary energy input to drive both half reactions.

Low‐dimensional copper halides with perovskite–analogue structure are a rapidly growing material family for light‐emitting and X‐ray screening devices. Among them Cs3Cu2I5 exhibits exceptional optoelectronic properties (large Stokes shift, high emission yield), due to the strong confinement effect of its 0D structure. However, its radioluminescence response to energetic ions has only marginally been explored and to heavy ions fully ignored due to the detrimental effect of luminescence quenching. Herein, the scintillation response of Cs3Cu2I5 thin layers to ions in a wide range of atomic mass and ionization density, as well as to electrons using the Compton‐coincidence technique, is investigated. The photon yield, linearity, and energy resolution are investigated as key parameters of the spectroscopic performance. Different semiempirical quenching models are used to better understand the relationship between the luminescence yield and the ionization density. The spectroscopic capability of polycrystalline Cs3Cu2I5 thin films is found on par with that of single‐crystal CsI:Tl to detect heavy ions. This makes easily processable thin‐film copper halides an attractive addition to the scintillator landscape.

Photoelectrochemistry is a promising method for the direct conversion of sunlight into valuable chemicals by combining the functions of solar panels and electrolyzers in one technology. In most studies, semiconductor/catalyst photoelectrode assemblies are used to achieve reasonable efficiencies. At the same time, unlike in dark electrochemical processes, the role of the catalyst is not straightforward in photoelectrochemistry, where the onset potential of the redox process should be mostly determined by the flatband potential of the semiconductor. In addition, the energy of holes (i.e., the surface potential) is independent of the applied bias; it is defined by the valence band (VB) position. In this study, we compared PdAu, Au, and Ni on Si photoanodes in the photoelectrochemical (PEC) oxidation of glycerol at record high current densities (> 180 mA cm-2), coupled to H2 evolution at the cathode. We successfully decreased the energy requirement (i.e., the cell voltage) of the paired conversion of glycerol and water by 0.7 V by exchanging the widely studied Ni catalyst with PdAu. The catalyst choice also dictates the product distribution, resulting mainly in C3 products on PdAu, glycolate (C2 product) on Au, and formate (C1 product) on Ni, without complete mineralization of glycerol (CO2 formation) that is difficult to rule out in dark electrochemical processes (as demonstrated by comparative measurements). Finally, we achieved a bias-free (standalone) operation with PdAu/Si and Au/Si photoanodes by combining the PEC oxidation of glycerol with oxygen reduction reaction (ORR).

This study demonstrates the electrochemical reduction of carbon monoxide (COR) at high current densities in a zero-gap electrolyzer cell and cell stack. By systematically optimizing both the commercially available membrane electrode assembly components (including binder content and gas diffusion layer) and the operating conditions, we could perform COR at current densities up to 1.4 A cm(-2) with a maximum C2+ selectivity of 90%. We demonstrated the scale-up to a 3 x 100 cm(2) electrolyzer stack that can sustain stable operation at 1 A cm(-2) for several hours without significant performance decay and with a total C2+ selectivity of similar to 80% and an ethylene selectivity of similar to 40%. We provide critical insights into the holistic optimization of key system parameters, without using special catalysts or surface additives, which can pave the way for scalable and industrially viable COR processes.

At eChemicles we are developing innovative sustainable electrolyzer technology to drive the transition of the chemical industry to reduce its environmental impact in a profitable way. Currently we are focusing on the electrolysis of CO 2 into CO, with a long-term goal to further electrochemically convert CO into ethylene. We will demonstrate CO 2 electrolysis to CO technology at operation environment in our first containerized prototype in early 2025, corresponding to TRL6. The core component of the stacks is our proprietary membrane electrode assembly (MEA). Starting from laboratory-scale (8 cm 2 ), through an intermediate step (100 cm 2 ), we scaled up our MEA to 2500 cm 2 . More than 2000 hours lifetime was demonstrated in the smallest scale, while hundreds of hours of operation is routinely achieved for the 100 cm 2 MEA now. A broad optimization work, including component selection, catalyst layer preparation, and operating parameter optimization is behind this advancement, with a holistic approach where the key performance indicators (cell / stack voltage, Faradaic efficiency, voltage degradation) are considered jointly. To further improve the performance and lifetime of our electrolyzers, we are developing conditioning protocols for our systems. Similar conditioning protocols are established for fuel cells and water electrolyzers, however, it is a scarcely studied field in CO 2 electrolysis. Our main goal is to shorten or eliminate the break-in period – a usually lower-performance and /or unstable operation period observed shortly after electrolyzer start-up. In my talk, I will present our results on the development of chemical and electrochemical conditioning steps with relation to CO 2 electrolysis. We have applied different current / voltage profiles before normal operation and investigated its impact on cell voltage, selectivity and long-term durability. Furthermore, we focus on the mechanistic understanding of the processes happening during the break-in period and stable operation (e.g., catalyst structural changes, cation balance) largely assisting the conditioning protocol development and the identification of MEA failure modes. Well-developed conditioning steps not only improve the reliability of the electrolyzers – a key figure of merit from an industrial point of view, but also crucial in the establishment of standardized testing protocols for short-term screening tests, which is the basis of efficient MEA development.

Ternary cesium-copper halide pseudo-perovskites are an emerging class of semiconductors in the field of optoelectronics. Similarly to metal-halide perovskites, by controlling the halide-composition, their emission properties can be fine-tuned. Here, a post-synthetic halide exchange method was employed to alter the halide-composition and thus the emission properties of polycrystalline Cs3Cu2Br5 layers.

Replacing Ir with anode catalyst materials that are more abundant is a long-sought objective within the CO2 electrolysis community. The chemical environment (near-neutral pH, carbonate buffer electrolyte) that inherently develops during long-term operation, however, limits the pool of applicable candidates. In this contribution, Ir was replaced with a porous Co3O4 nanosheet catalyst layer as the anode of a zero-gap CO2 electrolyzer cell. The catalyst was directly deposited on the Ti porous transport layer via hydrothermal synthesis, which allowed the precise control of the catalyst loading. Under optimal conditions (7 mg cm-2 Co3O4 loading), 300 mA cm-2 current density was reached at 3.4 V applied cell voltage. The electrolyzer cell with the Co3O4 anode was operated continuously for 50 hours at 250 mA cm-2 current density with stable cell voltage and CO2 reduction selectivity. In this proof-of-concept study, Co3O4 nanosheets were used as an anodic water oxidation catalyst in a CO2 electrolyzer cell, replacing Ir. Synthesized directly on Ti paper porous transport layer with an optimized catalyst loading, current densities of 300 mA cm−2 at 3.4 V. The CO2 electrolyzer operated continuously for over 50 hours at 250 mA cm−2, maintaining CO2 reduction selectivity and cell stability. This scalable synthesis method supports industrial-level CO2 electrolysis technology, offering a financially optimal alternative to Ir.