Electrochemical Research Articles

Ion solvation free energy calculations based on first-principles molecular dynamics thermodynamic integration.

Numerous electrochemistry reactions require the precise calculation of the ion solvation energy. Despite the significant progress in the first-principles calculations for crystals and defect formation energies for solids, the liquid system free energy calculations still face many challenges. Ion solvation free energies can be calculated via different semiempirical ways, e.g., using implicit solvent models or cluster of explicit molecule models; however, systematically improving these models is difficult due to their lack of a solid theoretical base. A theoretically sound approach for calculating the free energy is to use thermodynamic integration. Nevertheless, owing to the difficulties of self-consistent convergence in first-principles calculations for unphysical atomic configurations, the computational alchemy approach has not been widely used for first-principles calculations. This study proposes a general approach to use first-principles computational alchemy for calculating the ion solvation energy. This approach is also applicable for other small molecules. The calculated ion solvation free energies for Li+, Na+, K+, Be2+, Mg2+, and Ca2+ are close to the experimental results, and the standard deviation due to molecular dynamics fluctuations is within 0.06eV.

Recent Advances in Carbon-Based Single-Atom Catalysts for Electrochemical Oxygen Reduction to Hydrogen Peroxide in Acidic Media

Electrochemical oxygen reduction reaction (ORR) via the 2e− pathway in an acidic media shows great techno-economic potential for the production of hydrogen peroxide. Currently, carbon-based single-atom catalysts (C-SACs) have attracted extensive attention due to their tunable electronic structures, low cost, and sufficient stability in acidic media. This review summarizes recent advances in metal centers and their coordination environment in C-SACs for 2e−-ORR. Firstly, the reaction mechanism of 2e−-ORR on the active sites of C-SACs is systematically presented. Secondly, the structural regulation strategies for the active sites of 2e−-ORR are further summarized, including the metal active center, its species and configurations of nitrogen coordination or heteroatom coordination, and their near functional groups or substitute groups, which would provide available and proper ideas for developing superior acidic 2e−-ORR electrocatalysts of C-SACs. Finally, we propose the current challenges and future opportunities regarding the acidic 2e−-ORR pathway on C-SACs, which will eventually accelerate the development of the distributed H2O2 electrosynthesis process.

Design and synthesis of heteroleptic Ni(II) dipyrrin complexes for electrochemical proton reduction reactions: Cyclic voltammetric and theoretical studies

The effect of nuclearity on electrochemical hydrogen generation using new heteroleptic Ni(II) complexes containing redox-active dipyrrin and dithiocarbamate ligands has been described. Complexes 1–2 have been meticulously characterized by spectroscopic studies (ESI-MS, IR, 1H, 13C NMR, UV–vis) and their structures unambiguously confirmed by X-ray single crystal analyses. Electrocatalytic properties of the complexes toward hydrogen evolution reaction have been investigated by cyclic voltammetric studies in an organic medium in the presence of acetic acid as a weak proton source. Notably, complexes 1 and 2 produce H2 via doubly reduced Ni(II) species i.e. Ni(0) in the presence of acetic acid. Further, these complexes exhibited significant electrocatalytic activity (TOF: 264 (1) and 650 s−1 (2). Controlled potential electrolysis established a minimum Faradaic efficiency of 92 (1) and 96 % (2). Complex 2 exhibited higher turnover frequency relative to 1, while 1 showed lower overpotential (0.35 V) in comparison to 2 (0.45 V). The stability of the complexes and the amount of produced H2 has been investigated by bulk electrolysis study. A tentative mechanism (ECEC; E, electrons and C, chemical steps) and involved intermediate species for the proton reduction reaction for 1 has been established by theoretical studies.

Redox-neutral electrochemical decontamination of hypersaline wastewater with high technology readiness level.

Industrial hypersaline wastewaters contain diverse pollutants that harm the environment. Recovering clean water, alkali and acid from these wastewaters can promote circular economy and environmental protection. However, current electrochemical and advanced oxidation processes, which rely on hydroxyl radicals to degrade organic compounds, are inefficient and energy intensive. Here we report a flow-through redox-neutral electrochemical reactor (FRER) that effectively removes organic contaminants from hypersaline wastewaters via the chlorination-dehalogenation-hydroxylation route involving radical-radical cross-coupling. Bench-scale experiments demonstrate that the FRER achieves over 75% removal of total organic carbon across various compounds, and it maintains decontamination performance for over 360 h and continuously treats real hypersaline wastewaters for two months without corrosion. Integrating the FRER with electrodialysis reduces operating costs by 63.3% and CO2 emissions by 82.6% when compared with traditional multi-effect evaporation-crystallization techniques, placing our system at technology readiness levels of 7-8. The desalinated water, high-purity NaOH (>95%) and acid produced offset industrial production activities and thus support global sustainable development objectives.

Enhancing stability in Acetonitrile-Based Supercapacitors: Implementation of Di-Pyrrolidinium ionic salts

One of the main strategies to enhance the energy density of electrochemical double layer capacitors (EDLCs) is to surpass the limitations of traditional electrolyte operating voltages. In our study, a novel high-purity di-pyrrolidine based electrolyte salt, 1-butyl-3-dimethylpyrrolidinium di[bis(trifluoromethanesulfonyl)imide] (C4di[mPyr].di[TFSI]) is synthesized, and high voltage electrolyte using acetonitrile (AN) as the sole solvent is prepared for EDLCs. The 0.5 M C4di[mPyr].di[TFSI]/AN electrolyte demonstrates an impressive electrochemical stability window of 6.04 V and a high operating voltage of 3.4 V, which is almost the highest stability reported so far for low concentration AN-based electrolytes. The impedance and conductivity of the 0.5 M C4di[mPyr].di[TFSI]/AN electrolyte are highly comparable to commercial 1.0 M TEA.BF4/AN electrolyte. EDLCs equipped with the electrolyte can maintain specific capacitance retentions of 94.92 % and 77.78 % after 2000 cycles at 3.4 V and 3.6 V, respectively. Besides, the GC–MS and XPS further prove its stability and confirm the possible electrochemical reactions of the C4di[mPyr].di[TFSI]/AN electrolyte on the electrode surface under the polarized voltages. Furthermore, the XPS also appears to show a relatively weak interaction between TFSI− and the electrode, which may serve as a potential factor in inhibiting the hydrolysis of TFSI− and the polymerization of AN.

Efficient preparation of metallic titanium from lower valence titanium chloride slurry by electrochemical reduction in molten salts

Short extraction of metallic titanium by the electrochemical reduction process in molten salt has attracted increasing interest due to its many advantages. The electrolysis of high-purity titanium to produce lower valence titanium chlorides has so far been industrialized as balancing agents but large-scale production is still challenging due to the high cost of raw materials and easy deterioration. Herein, metallic titanium was extracted from lower valence titanium chlorides (LTCs) slurries by electrochemical reduction in molten salts. The results of LTC slurries at 260 ºC for 48 h revealed the formation of red-violet α- and γ- TiCl3 with an Al content below 0.09 wt%, which gradually reduced to form metallic titanium in molten salt electrolytes. Porous metallic Ti powders were obtained from TiCl3 by electrochemical reduction in KCl-LiCl-MgCl2 molten salt at 400 °C. The reaction at the anode area was accompanied by TiCl4 gas overflow, and continuous electrolysis of metallic titanium was achieved by supplementing the consumed TiCl3. Overall, the proposed electrolysis process looks promising for large-scale applications due to its simple electrolysis equipment, relatively stable electrolyte components, and good product quality, thereby worth further future investigation.

Synthesis of N‐propanol from CO2 Electroreduction on Bicontinuous Cu2O/Cu Nanodomains

n‐propanol is an important pharmaceutical and pesticide intermediate. To produce n‐propanol by electrochemical reduction of CO2 is a promising way, but is largely restricted by the very low selectivity and activity. How to promote the coupling of *C1 and *C2 intermediates to form the *C3 intermediate for n‐propanol formation is challenging. Here, we propose the construction of bicontinuous structure of Cu2O/Cu electrocatalyst, which consists of ultra‐small Cu2O nanodomains, Cu nanodomains and large amounts of grain boundaries between Cu2O and Cu nanodomains. The n‐propanol current density is as high as 101.6 mA cm−2 at the applied potential of −1.1 V vs. reversible hydrogen electrode in flow cell, with the Faradaic efficiency up to 12.1%. Moreover, the catalyst keeps relatively stable during electrochemical CO2 reduction process. Experimental studies and theoretical calculations reveal that the bicontinuous structure of Cu2O/Cu can facilitate the *CO formation, *CO‐*CO coupling and *CO‐*OCCO coupling for the final generation of n‐propanol.

Synthesis of N-propanol from CO2 Electroreduction on Bicontinuous Cu2O/Cu Nanodomains.

n-propanol is an important pharmaceutical and pesticide intermediate. To produce n-propanol by electrochemical reduction of CO2 is a promising way, but is largely restricted by the very low selectivity and activity. How to promote the coupling of *C1 and *C2 intermediates to form the *C3 intermediate for n-propanol formation is challenging. Here, we propose the construction of bicontinuous structure of Cu2O/Cu electrocatalyst, which consists of ultra-small Cu2O nanodomains, Cu nanodomains and large amounts of grain boundaries between Cu2O and Cu nanodomains. The n-propanol current density is as high as 101.6 mA cm-2 at the applied potential of -1.1 V vs. reversible hydrogen electrode in flow cell, with the Faradaic efficiency up to 12.1%. Moreover, the catalyst keeps relatively stable during electrochemical CO2 reduction process. Experimental studies and theoretical calculations reveal that the bicontinuous structure of Cu2O/Cu can facilitate the *CO formation, *CO-*CO coupling and *CO-*OCCO coupling for the final generation of n-propanol.

A sustainable electrochemical strategy utilizing pulsed alternating current and dual carbon felt electrodes for enhanced degradation of organic pollutants: Oxidation performance and mechanisms

In this work, a novel electrochemical (EC) oxidation system utilizing pulsed alternating current (PAC) and dual carbon felt (CF) electrodes has been established for sustainable degradation of sulfamethoxazole (SMX) with no addition of extra oxidant. The EC/PAC system showed high degradation efficiency and energy efficiency compared to the pulsed direct current (PDC) and direct current (DC) systems. The EC/PAC process was effective across a wide pH range of 3–11 for SMX removal. The results showed that the 1O2 confined to the CF electrode surface was the dominant oxidative specie that was generated from dissolved oxygen in the system. Under PAC conditions, the cathode and anode were rapidly switched on the same CF electrode, increasing the generation of 1O2 for enhanced SMX oxidation. Furthermore, the EC/PAC system demonstrated resistance to interference from various anions of different concentration levels found in natural environment. In contrast to the EC/PDC system, the EC/PAC system emerged as a promising option for more efficient H2O2 production. High-resolution mass spectrometry results revealed the SMX degradation pathways and byproducts, which were then evaluated for toxicity removal. Overall, the EC/PAC system offers a green and sustainable solution to future wastewater treatment, with high degradation rates, energy efficiency, and sustainability.

Efficient electro-Fenton degradation of organic pollutants via the synergistic effect of 1O2 and •OH generated on single Fe[sbnd]N4 sites

The electro-Fenton with in situ generated 1O2 and •OH is a promising method for the degradation of micropollutants. However, its application is hindered by the lack of catalysts that can efficiently generate 1O2 and •OH from electrochemical oxygen reduction. Herein, N-doped stacked carbon nanosheets supported Fe single atoms (Fe-NSC) with FeN4 sites were designed for simultaneous generation of 1O2 and •OH to enhance electro-Fenton degradation. Due to the synergistic effect of 1O2 and •OH, a variety of contaminants (phenol, 2,4-dichlorophenol, sulfamethoxazole, atrazine and bisphenol A) were efficiently degraded with high kinetic constants of 0.037–0.071 min−1 by the electro-Fenton with Fe-NSC as cathode (−0.6 V vs Ag/AgCl, pH 6). Moreover, the superior performance for electro-Fenton degradation was well maintained in a wide pH range from 3 to 10 even with interference of various inorganic salt ions. It was found that FeN4 sites with pyridinic N coordination were responsible for its good performance for electro-Fenton degradation. Its 1O2 yield was higher than •OH yield, and the contribution of 1O2 was more significant than •OH for pollutant degradation.

Electrochemical Nitro Reduction to Amines Using Pinacolborane as Reducing Agents

Nitroaromatic compounds, as hazardous industrial pollutants, have long been extensively studied for their conversion into high-value aromatic amines. However, most of these transformation reactions are confined to the use of transition metal catalysts or high-temperature conditions. Therefore, we report an electrochemical approach utilizing Pinacolborane as the reducing agent for the efficient reduction of nitroaromatic compounds. The reaction is characterized by its mild conditions, simplicity in operation, and demonstrates excellent substrate adaptability and functional group compatibility.

Electrocatalytic Glycerol Conversion: A Low-Voltage Pathway to Efficient Carbon-Negative Green Hydrogen and Value-Added Chemical Production.

Electrochemical glycerol oxidation reaction (GLYOR) could be a promising way to use the abundantly available glycerol for production of value-added chemicals and fuels. Completely avoiding the oxygen evolution reaction (OER) with GLYOR is an evolving strategy to reduce the overall cell potential and generate value-added chemicals and fuels on both the anode and cathode. We demonstrate the morphology-controlled palladium nanocrystals, afforded by colloidal chemistry, and their established morphology-dependent GLYOR performance. Although it is known that controlling the morphology of an electrocatalyst can modulate the activity and selectivity of the products, still it is a relatively underexplored area for many reactions, including GLYOR. Among nanocube (Pd-NC), truncated octahedron (Pd-TO), spherical and polycrystalline (Pd-PC) morphologies, the Pd-NC electrocatalyst deposited on a Ni foam exhibits the highest glycerol conversion (85%) along with 42% glyceric acid selectivity at a low applied potential of 0.6 V (vs reversible hydrogen electrode (RHE)) in 0.1 M glycerol and 1 M KOH at ambient temperature. Owing to the much favorable thermodynamics of GLYOR on the Pd-NC surface, the assembled electrolyzer requires an electricity input of only ∼3.7 kWh/m3 of H2 at a current density of 100 mA/cm2, in contrast to the requirement of ≥5 kWh/m3 of H2 with an alkaline/PEM electrolyzer. Sustainability has been successfully demonstrated at 10 and 50 mA/cm2 and up to 120 h with GLYOR in water and simulated seawater.

Electrochemical Restructuring Driven Catalytic Cycle of Bi-Based Heterojunctions for High-Performance Lithium-Sulfur Batteries.

Restructuring is an important phenomenon in catalytic reactions. Conversion-type materials with suitable redox potential may undergo in situ electrochemically driven restructurings and induce highly active catalytic sites in a working lithium-sulfur battery. Herein, driven by the electrochemical conversion reaction of BiVO4, a reversible catalytic cycle of Bi/amorphous Li3VO4 (a-Li3VO4) and Bi2S3/a-Li3VO4 heterojunctions is constructed, which targets the oxidation of Li2S and the conversion of polysulfide, respectively. The heterostructures and electrochemically driven size confinement provide abundant sites for shuttle restraining and sulfur conversion. Especially, the p-block Bi and Bi2S3 could dramatically reduce the conversion energy barriers of Li2S and polysulfide by virtue of the p-p orbital hybridization, promoting bidirectional reactions of the sulfur cathode. As a result, the corresponding sulfur cathode possesses a high reversible capacity of 7.5 mAh cm-2 after 120 cycles under a high sulfur loading of 10.3 mg cm-2 with a current density of 0.38 mA cm-2. This study furnishes a feasible scheme to obtain highly effective catalysts for bidirectional sulfur redox by utilizing the electrochemically induced restructuring.

The Simultaneous Efficient Recovery of Ammonia Nitrogen and Phosphate Resources in the Form of Struvite: Optimization and Potential Applications for the Electrochemical Reduction of NO3−

In response to the need for improvement in the utilization of ammonium-rich solutions after the electrochemical reduction of nitrate (NO3−–RR), this study combined phosphorus-containing wastewater and adopted the electrochemical precipitation method for the preparation of struvite (MAP) to simultaneously recover nitrogen and phosphorus resources. At a current density of 5 mA·cm−2 and an initial solution pH of 7.0, the recovery efficiencies for nitrogen and phosphorus can reach 47.15% and 88.66%, respectively. Under various experimental conditions, the generated struvite (MgNH4PO4·6H2O) exhibits a typical long prismatic structure. In solutions containing nitrate and nitrite, the coexisting ions have no significant effect on the final product, struvite. Finally, the characterization of the precipitate product by X-ray diffraction (XRD) revealed that its main component is struvite, with a high purity reaching 93.24%. Overall, this system can effectively recover ammonium nitrogen from the NO3−–RR solution system after nitrate reduction, with certain application prospects for the recovery of ammonium nitrogen and phosphate.

Ru-Doped NiFe-MIL-53 with Facilitated Reconstruction and Active Hydrogen Supplement for Enhanced Nitrate Reduction.

The Electrochemical reduction of nitrate to ammonia (NH3) is a process of great significance to energy utilization and environmental protection. However, it suffers from sluggish multielectron/proton-involved steps involving coupling reactions between different reaction intermediates and active hydrogen species (Hads) produced by water decomposition. In this study, a Ru-doped NiFe-MIL-53 (NiFeRu-MIL-53) supported on Ni foam (NF) has been designed for the nitrate reduction reaction (NO3RR). The NiFeRu-MIL-53 exhibits excellent NO3RR activity with a maximum Faradaic efficiency (FE) of 100% at -0.4 V vs. RHE for NH3 and a maximum NH3 yield of 62.39 mg h-1 cm-2 at -0.7 V vs. RHE in alkaline media. This excellent performance for the NO3RR is attributed to a strong synergistic effect between Ru and reconstructed NiFe(OH)2. Additionally, the doped Ru facilitates water dissociation, leading to an appropriate supply of Hads required for N species hydrogenation during NO3RR, thereby further enhancing its performance. Furthermore, in situ Raman analysis reveals that incorporating Ru facilitates the reconstruction of MOFs and promotes the formation of hydroxide active species during the NO3RR process. This work provides a valuable strategy for designing electrocatalysts to improve the efficiency of the reduction of electrochemical nitrate to ammonia.

Continuous Flow‐By Electrochemical Reactor Design for Direct Lithium Extraction from Brines

AbstractThe demand for lithium is expected to increase significantly in the next few years, mainly due to the energy transition in the mobility sector. To electrify the entire global transportation system, it is necessary to have access to a wide variety of lithium deposits to ensure resource sovereignty and sufficient supply to meet demand. For this reason, much effort has recently been invested in developing technologies for direct lithium extraction (DLE) from brines. In this work, a membrane‐based continuous flow‐by reactor for the electrochemical extraction of lithium from brine with a LiMn2O4/λ‐MnO2 system has been studied. A zoned reactor was proposed in which the current density and electrode mass loading gradually decrease along with the depletion of lithium in the brine, obtaining an average electrode capacity of 80 mAh/g throughout three different reactor sections. The limiting Reynolds number was determined for the dilute lithium segment of the reactor to avoid mass transport limitations, with brine concentration equal to Li 3 mM and Na 1.3 M. A homogeneous cycle time was achieved for the three reactor zones and their associated average energy consumption was determined, ranging from 3.9 Wh/mol Li to 9.5 Wh/mol Li.

Analysis of discharge performance and thermo-electric conversion efficiency in thermally regenerative ammonia-based flow battery with foam copper electrode

This paper established a numerical model of mass transport and electrochemical reaction coupling in porous media of thermally regenerative ammonia-based flow battery with foam copper electrode (TRAFB-FCE) for the first time. The effects of the structural parameters of the foam copper electrode on the power density, energy density, discharge capacity, and active species distribution of the battery were comprehensively studied based on the coupled numerical model. Special attention was paid to the selection strategy of the initial reactant concentration for the battery under different discharge conditions. The results suggest that increasing the porosity or thickness of the foam copper electrode causes the voltage and power density of the battery to first increase and then decrease, while the discharge capacity and energy density monotonically increase. Moreover, the battery should avoid discharging at current densities exceeding 720 A·m−2. When the discharge current density is less than 200 A·m−2, it is preferable to set the initial concentration of Cu2+ to 0.4 mol/L, while the discharge current density is in the range of 200–720 A·m−2, the initial concentration of Cu2+ is preferable to be 0.3 mol/L. When it discharges at about 5 % of its maximum power density, the Carnot-relative efficiency of this battery is comparable to the highest value currently reported in the field of liquid-based thermo-electric conversion achieved by the Thermal Regenerative Electrochemical Cycle (TREC) technology, and the power density of the former is 8.87 times that of the latter.

A combined density functional theory and microkinetics simulations study of electrochemical CO2 reduction on Cu8/SnO2(110): The crucial role of hydrogen coverage

The electrochemical reduction of CO2 (eCO2R) is a promising approach for converting CO2 into valuable chemicals and fuels using renewable energy sources. We investigated the mechanism of eCO2R for a small Cu8 cluster placed on SnO2 containing O vacancies using density functional theory and predicted current density and selectivity by microkinetics simulations within the computational hydrogen electrode model. Low and high H coverages were modeled by Cu8/SnO2-x and Cu8H6/SnO2-x models, using statistical methods to identify their most stable structures. Different CO2 adsorption modes on Cu8/SnO2-x and Cu8H6/SnO2-x surface models, all containing an O vacancy, resulted in distinct reaction pathways, leading to either HCOOH or CO. The preferred formation of HCOOH occurred upon CO2 adsorption on an O vacancy on the Cu8H6/SnO2-x surface, followed by sequential hydrogenation to HCOO and HCOOH. Adsorption of CO2 on Cu8/SnO2-x opened a facile pathway to CO. Electronic structure analysis revealed that differences in charge donation of Cu to the antibonding orbitals of CO2 can explain the predicted selectivity differences. The preferred adsorption mode of CO2 is bidentate at the Cu-SnO2-x interface. Our findings emphasize the role of H coverage on Cu on the selectivity of eCO2R for Cu/SnOx catalysts.

Using Sandwiched Silicon/Reduced Graphene Oxide Composites with Dual Hybridization for Their Stable Lithium Storage Properties

Using silicon/reduced graphene oxide (Si/rGO) composites as lithium-ion battery (LIB) anodes can effectively buffer the volumetric expansion and shrinkage of Si. Herein, we designed and prepared Si/rGO-b with a sandwiched structure, formed by a duple combination of ammonia-modified silicon (m-Si) nanoparticles (NP) with graphene oxide (GO). In the first composite process of m-Si and GO, a core–shell structure of primal Si/rGO-b (p-Si/rGO-b) was formed. The amino groups on the m-Si surface can not only hybridize with the GO surface to fix the Si particles, but also form covalent chemical bonds with the remaining carboxyl groups of rGO to enhance the stability of the composite. During the electrochemical reaction, the oxygen on the m-Si surface reacts with lithium ions (Li+) to form Li2O, which is a component of the solid–electrolyte interphase (SEI) and is beneficial to buffering the volume expansion of Si. Then, the p-Si/rGO-b recombines with GO again to finally form a sandwiched structure of Si/rGO-b. Covalent chemical bonds are formed between the rGO layers to tightly fix the p-Si/rGO-b, and the conductive network formed by the reintroduced rGO improves the conductivity of the Si/rGO-b composite. When used as an electrode, the Si/rGO-b composite exhibits excellent cycling performance (operated stably for more than 800 cycles at a high-capacity retention rate of 82.4%) and a superior rate capability (300 mA h/g at 5 A/g). After cycling, tiny cracks formed in some areas of the electrode surface, with an expansion rate of only 27.4%. The duple combination of rGO and the unique sandwiched structure presented here demonstrate great effectiveness in improving the electrochemical performance of alloy-type anodes.

Switching CO2 Electroreduction toward Ethanol by Delocalization State-Tuned Bond Cleavage.

The electrochemical CO2 reduction reaction by copper-based catalysts features a promising approach to generate value-added multicarbon (C2+) products. However, due to the unfavored formation of oxygenate intermediates on the catalyst surface, the selectivity of C2+ alcohols like ethanol remains unsatisfactory compared to that of ethylene. The bifurcation point (i.e., the CH2═CHO* intermediate adsorbed on Cu via a Cu-O-C linkage) is critical to the C2+ product selectivity, whereas the subsequent cleavage of the Cu-O or the O-C bond determines the ethanol or ethylene pathway. Inspired by the hard-soft acid-base theory, in this work, we demonstrate an electron delocalization tuning strategy of the Cu catalyst by a nitrene surface functionalization approach, which allows weakening and cleaving of the Cu-O bond of the adsorbed CH2═CHO*, as well as accelerating hydrogenation of the C═C bond along the ethanol pathway. As a result, the nitrene-functionalized Cu catalyst exhibited a much-enhanced ethanol Faradaic efficiency of 45% with a peak partial current density of 406 mA·cm-2, substantially exceeding that of unmodified Cu or amide-functionalized Cu. When assembled in a membrane electrode assembly electrolyzer, the catalyst presented a stable CO2-to-ethanol conversion for >300 h at an industrial current density of 400 mA·cm-2.