CO₂ feedstock obtained from point sources, such as chemical industries or fossil fuel-based power plants, typically contains gaseous contaminants such as SO_x, NO_x, H₂S, and COS, which can be detrimental to the catalysts used to electrochemically convert CO₂/CO into valuable fuels and chemicals. A significant suppression of C₂₊ products is observed even in the presence of 10 ppm of these impurities due to catalyst poisoning and a selectivity change. Hence, it is necessary to have an upstream cleaning process to maintain a high selectivity toward high value C₂₊ products and to reduce the operational costs associated with frequent catalyst regeneration or replacement. We present a comprehensive process model and technoeconomic analysis of an integrated large-scale two-step CO₂/CO electroreduction plant that produces C₂₊ products including ethylene, acetic acid, ethanol, and n-propanol, using blast furnace gas obtained from a steel manufacturing facility as feedstock. Detailed modeling and integration of the upstream cleaning units, CO₂/CO electrolyzers, and the downstream separation of gas/liquid products are performed using Aspen Plus. Our analysis shows that the large-scale two-step CO₂/CO electroreduction process is not profitable under the base case scenario and requires significant improvements in electrolyzer performance, reduction in capital costs, and favorable market conditions to improve the economics. The upstream cleaning units only contribute to ∼15% of the CAPEX and ∼8% OPEX of the entire plant, while the electrolyzers contribute to ∼63% of the total CAPEX and OPEX. A positive net present value ($54M), a payback time of 13 years, and an internal rate of return of 12.8% can be achieved when the electrolyzer capital cost is $10,000/m² (−50%) and electricity price is $20/MWh (−50%), with current densities of 750 mA/cm² (+50%) for both electrolyzers and cell voltages of 2.5 V (−17%) for CO₂R and 2.0 V (−20%) for COR electrolyzers, and when the product prices are 35% higher than the current market prices. Incorporating an energy-saving coelectrolysis process or integration into facilities that can directly utilize the products can accelerate the commercialization of the two-step CO₂/CO electroreduction process.

Ammonia (NH₃) is vital for synthesizing fertilizers and has gained great attention as a carbon-free hydrogen carrier and a hydrogen-rich fuel. Electrochemical ammonia synthesis from nitrate in a water-fed polymer electrolyte membrane electrolyzer is an innovative approach to wastewater treatment. However, the major hurdles to practical implementation are competing hydrogen evolution reactions (HERs) and constrained catalytic efficiency. Herein, we demonstrate the use of polyvinylpyrrolidone (PVP)-modified ruthenium (Ru) nanoparticles as a strategy to drive the desired reaction of nitrate to ammonia. The particle size of Ru was controlled by PVP, enhancing the metal-utilization efficiency and the electrochemical active surface area. PVP modification was found to alter the electron density on Ru, suppressing the HER by increasing the energy barrier of hydrogen coupling to form H₂, while promoting absorbed hydrogen (H*) formation, facilitating the hydrogenation of intermediates to ammonia. Benefiting from the combined effects, PVP-10 wt % Ru/C achieved an ammonia production rate of 3800 μg·mg_Ru^–1·h^–1, compared to 590 μg·mg_Ru^–1·h^–1 for 40 wt % Ru/C at 2 V.

Direct air capture and CO₂ conversion will play vital roles in a future circular carbon economy. Here, we propose a novel system for integrated CO₂ capture and conversion through the combined use of solid and liquid sorbents and demonstrate its technical feasibility. CO₂ is initially captured from the air using an amine-functionalized solid sorbent that is regenerated by rinsing with an aqueous carbonate-rich solution. The resulting bicarbonate-rich solution is fed to an electrolyzer, converting the bicarbonate electrolyte to syngas. Through our experiments, we demonstrate that the dual-sorbent system is capable of capture from air as well as solid sorbent regeneration and CO₂ conversion. We use a simplified process model based on experimental results to explore the effects of scaling the components of the proposed system. We find that the pH-swing between the rich and lean solutions is a dominant design parameter, which is almost exclusively governed by the electrolyzer sizing. A small pH swing results in an improved electrolyzer performance and beneficial syngas composition, whereas a large pH swing results in efficient solid sorbent use and decreased water loss. Our results further highlight the fundamental trade-offs that are present when designing integrated capture and conversion systems.

The electrochemical reduction of CO₂ using copper-based catalysts represents a promising pathway for producing multi-carbon products from renewable energy. Temperature is a key parameter that not only determines reaction pathways and product selectivity but also strongly affects catalyst stability, electrolyte composition, and membrane integrity. Despite its importance, most studies have primarily focused on catalytic selectivity, often overlooking the thermal and stability aspects recently emphasized in the literature. This perspective underscores the central role of temperature in governing both catalytic performance and the physical and chemical resilience of electrolyzer components under low-temperature (20–80 °C) conditions. These factors become even more critical during scale-up, where heat management and transfer directly influence efficiency and long-term durability, similar to challenges in hydrogen production systems. A comprehensive understanding of thermal effects on both catalytic and non-catalytic elements is therefore essential for optimizing system performance. This work proposes experimental methodologies to evaluate the thermal and chemical stability of catalysts, electrolytes, and membranes, and outlines future research directions aimed at enabling the practical, efficient, and scalable deployment of CO₂ electrolysis through improved thermal design and integrated heat management.

Electrochemical CO₂ reduction to CO offers a sustainable route for converting CO₂ into value-added chemicals and fuels. However, CO₂ streams derived from industrial sources often contain SO₂ impurities that severely poison conventional metal-based catalysts. Here, we report a nitrogen-doped carbon catalyst that exhibits pronounced tolerance and stability for CO₂-to-CO conversion in the presence of SO₂ (100–10,000 ppm). The catalyst maintains over 90% Faradaic efficiency toward CO during 8 h of electrolysis at −1.0 V vs RHE with 100 ppm of SO₂, whereas Ag foil electrodes undergo rapid deactivation. Density functional theory calculations combined with surface analyses indicate that weak SO₂ adsorption and the absence of stable sulfur accumulation on nitrogen-doped carbon strengthen its resistance to impurity-induced deactivation, in contrast to Ag catalysts that form Ag₂S. Gas-fed tests in a membrane electrode assembly (MEA) electrolyzer further confirm that nitrogen-doped carbon sustains high CO selectivity at elevated current densities, while Ag nanoparticles suffer irreversible sulfur poisoning. These results demonstrate that nitrogen-doped carbon is intrinsically resistant to SO₂-induced deactivation and highlight its potential as a robust catalyst for CO₂ electroreduction under impurity-containing conditions.

For battery architectures that need a solid ion conductor with good contacting performance and high stability against electrochemical oxidation, polymerized ionic liquids (PIL) pose a valuable class of materials. The low conductivity of the binary PIL/ lithium salt system can be increased using a ternary ionic liquid acting as plasticiser. The conductive mechanism of the ternary system is however not fully understood. This work shows the shift in conduction mechanism for the ternary Li−/[1,3]PYR-/PDADMA-FSI system by increasing the lithium salt concentration and comparing the transfer mechanism to binary ionic liquid (IL) electrolyte analogues using pulsed field gradient (PFG) nuclear magnetic resonance (NMR), NMR relaxometry, Raman spectroscopy and electrochemical techniques. Two conducting regimes were found which show a strong trade-off between conductivity and transference number. In the low lithium salt regime (≤35 wt% LiFSI), cluster diffusion of aggregated lithium is the dominating mechanism leading to low transference numbers (0.04–0.15 at room temperature (RT)). The high salt regime (≥50 wt% LiFSI) shows diffusion through free lithium ion hopping transfer, which has a stronger dependence on temperature and yields higher transference numbers (0.31 at RT). Increasing lithium salt concentration shows an inverse linear correlation with conductivity. The electrochemical characteristics of ternary IL/PIL/lithium salt are shown to be highly tuneable by varying the lithium salt fraction, while it maintains excellent characteristics like processability, stability and mechanical function.

Fluorination of electrolytes has been a widely used strategy to enable stable cycling in lithium metal batteries. However, a move toward fluorine-free electrolytes is desirable given the safety and environmental concerns surrounding fluorinated materials. Designing these electrolytes requires a comprehensive understanding of bulk electrolyte and interfacial properties in the absence of fluorine, particularly the solvation structures surrounding Li⁺ and the solid electrolyte interface (SEI) composition. Among fluorine-free Li salts, lithium nitrate (LiNO₃) is often used to obtain highly ion-conductive SEI components. However, its poor ion dissociation and rapid consumption upon freshly plated lithium currently hinder its use as the main electrolyte salt. Herein, we show that the modification of Li⁺ inner solvation structures by employing lithium bis(oxalato)borate (LiBOB) as the secondary salt in LiNO₃/diglyme electrolytes synergistically improves both bulk Li⁺ transport and SEI properties. It significantly enhances ion dissociation, which increases the ionic conductivity of the electrolyte despite an increase in its viscosity. Furthermore, the presence of LiBOB-derived outer SEI components over the LiNO₃-derived ion-conductive inner SEI layer results in low-surface-area Li deposits and lower Li⁺/anion consumption during cycling. The dual-salt fluorine-free electrolyte enables stable, long-term cycling in Li/Cu cells for >700 cycles and shows promising capacity retention in Li/LFP full cells at ambient temperature. Our work highlights the importance of tuning the Li⁺ solvation structures for optimizing bulk and interface properties in fluorine-free electrolytes and presents a viable pathway toward the development of greener electrolytes for lithium metal batteries.

We demonstrate a hybrid electrolyzer design for CO₂electrolysis to multicarbon products using a cation exchange membrane and different electrode separations. Reducing the thickness of the catholyte flow field from 5 to 2.4 mm significantly decreases the cell voltage while maintaining longer-term stability.

Recent progress in the electrochemical reduction of CO₂ (CO₂RR) has led to notable breakthroughs in generating C₂ compounds such as ethylene and ethanol. Nevertheless, the direct formation of C₃ products encounters significant limitations due to the C₂–C₁ coupling reaction, posing a considerable challenge to improving their faradaic efficiency. Here, a design for an elevated pressure cascade catalytic reactor to convert CO₂ to C₃ products in a two-step electrochemical process is presented. At 25 bar pressure, by regulating the potential of the cascade system and the electrolyte flow rate, a 40% selectivity for 2-propanol on a copper electrode placed upstream of a silver electrode that converts CO₂ to CO is reported. In cascade mode (with both silver and copper electrodes active), the C₃:C₂ oxygenate ratio significantly increases to 7 compared to the noncascade mode (copper only) with a modest ratio of about 0.6. Therefore, our elevated pressure cascade electrolysis approach demonstrates a notable step forward in CO₂ electroreduction to oxygenated C₃ products.

Synthetic fertilizers are required to sustain the increasing human population. Out of the many different types of fertilizers, ammonium nitrate is the most widely used type. Currently, both nitrate and ammonia are produced via energy-intensive processes, requiring high temperatures and pressures. Therefore, to make the production of the necessary fertilizers more sustainable, alternative production methods are required. One of those potential routes is electrochemical synthesis. While the electrochemical reduction of dinitrogen to ammonia has been investigated thoroughly, the synthesis of nitrate has not received as much attention. In this review, we review two different routes for the electrochemical synthesis of nitrate, starting from either molecular nitrogen or ammonia. We show that the reaction conditions can significantly alter the selectivity of ammonia oxidation. Consequently, this means that a catalyst currently tailored for oxidising ammonia to dinitrogen could potentially be used for ammonia oxidation to nitrate. Meanwhile, the direct electrochemical oxidation of molecular nitrogen suffers from false positives due to contaminations, similar to electrochemical nitrogen reduction. The current published results still lack proper control experiments, making the outcomes for now unreliable. In conclusion, for dinitrogen oxidation research, we suggest rigorous testing procedures to exclude false positive results.

Electrochemical CO₂ reduction in non-aqueous solvents is promising due to the increased CO₂ solubility of organic-based electrolytes compared to aqueous electrolytes. Here the effect of nine different salts in propylene carbonate (PC) on the CO₂ reduction product distribution of polycrystalline Cu is investigated. Three different cations (tetraethylammonium (TEA), tetrabutylammonium (TBA), and tetrahexylammonium (THA)) and three different anions (chloride (Cl), tetrafluoroborate (BF₄), and hexafluorophosphate (PF₆)) were used. Chronoamperometry and in-situ FTIR measurements show that the size of the cation has a crucial role in the selectivity. A more hydrophobic surface is obtained when employing a larger cation with a weaker hydration shell. This stabilizes the CO₂⁻ radical and promotes the formation of ethylene. CO₂ reduction in 0.7 M THACl/PC shows the highest hydrocarbon formation. Lastly, we hypothesize that the hydrocarbon formation pathway is not through C−C coupling, as the CO solubility in PC is very high, but through the dimerization of the COH intermediate.

In this study, the effect of halide anions on the selectivity of the CO₂ reduction reaction to CO was investigated in choline-based ethylene glycol solutions containing different halides (ChCl : EG, ChBr : EG, ChI : EG). The CO₂RR was studied using silver (Ag) and gold (Au) electrodes in a compact H-cell. Our findings reveal that chloride effectively suppresses the hydrogen evolution reaction and enhances the selectivity of carbon monoxide production on both Ag and Au electrodes, with relatively high selectivity values of 84 % and 62 %, respectively. Additionally, the effect of varying ethylene glycol content in the choline chloride-containing electrolyte (ChCl : EG 1 : X, X=2, 3, 4) was investigated to improve the current density during CO₂RR on the Ag electrode. We observed that a mole ratio of 1 : 4 exhibited the highest current density with a comparable faradaic efficiency toward CO. Notably, an evident surface reconstruction process took place on the Ag surface in the presence of Cl⁻ ions, whereas on Au, this phenomenon was less pronounced. Overall, this study provides new insights into anion-induced surface restructuring of Ag and Au electrodes during CO₂RR, and its consequences on the reduction performance on such surfaces in non-aqueous electrolytes.

In this study, we experimentally screen a promising class of intermetallic alloys for the electrochemical reduction of CO₂ toward hydrocarbon products. Based on previous DFT-based screening papers, combinations of strongly CO-binding metals such as iron, cobalt, and nickel with weakly CO-binding metals such as gallium, aluminium or zinc were selected as potentially promising catalytic materials. Despite the challenging production of these alloys, we report a general two-step synthesis method for intermetallic alloys and discuss the specific synthesis conditions that must be taken into account when synthesising these materials. After their synthesis, we use a recently developed differential electrochemical mass spectrometry (DEMS) setup to rapidly quantify the CO₂ reduction products over a range of potentials. Almost all newly developed intermetallic catalysts are shown to produce methane and ethylene, while the CoSn catalyst showed higher selectivity towards formate production. However, all tested catalysts mostly produced hydrogen and only reduce CO₂ to a small extent, despite the favourable computational screening results. We discuss possible reasons for this discrepancy and outline a more holistic approach for linking future DFT studies with experiments.

Electrochemical CO₂ reduction is a promising way of closing the carbon cycle while synthesizing useful commodity chemicals and fuels. One of the possible routes to scale up the process is CO₂ reduction at elevated pressure, as this is a way to increase the concentration of poorly soluble CO₂ in aqueous systems. Yet, not many studies focus on this route, owing to the inherent challenges with high-pressure systems, such as leaks, product quantification, and ease of operation. In this study, we use a high-pressure flow cell setup to investigate the impact of CO₂ pressure on the electrochemical performance of a copper foam electrode for CO₂ reduction within a pressure range of 1 to 25 bar. Our initial findings using a 0.5 M potassium bicarbonate (KHCO₃) electrolyte show a consistent improvement in selectivity towards CO₂ reduction products, with HCOOH being the dominant product. By conducting a systematic exploration of operating parameters including applied current density, applied CO₂ pressure, cation effect, and electrolyte concentration, the selectivity towards formate (HCOOH) is optimized, achieving a remarkable 70 % faradaic efficiency (FE) under moderate conditions of 25 bar in a 0.5 M cesium bicarbonate (CsHCO₃) electrolyte. Additionally, we report the synthesis of isopropanol with a FE of 11 % at the 25 bar in 0.5 M KHCO₃ which is the highest reported selectivity towards isopropanol on copper using a bicarbonate system.