bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficient Ni-NC Gas Diffusion Electrodes for CO2 Electrolyzer with High Utilization Efficiencies and Single Pass Conversions Towards CO
Authors: Brueckner Sven , Ju Wen , Strasser Peter 
Published: August 2024

The electrochemical CO2 reduction in membrane electrolyzer devices can become a key technology to close the anthropologic carbon cycle. For industrialisation of CO2 electrolyzers, however, performance shortcomings of today’s state-of-art electrolyzer designs and cathodes have to be addressed. Alkaline Membrane CO2 electrolyzers suffer from low utilization efficiency of CO2 due to an acid-base CO2 loss to carbonates, which limits the CO2 utilization efficiency and single pass conversion to 50% in AEM CO2-to-CO electrolyzer. Bipolar Membrane CO2 electrolyzers suffer from high cell voltage and lower Faradic efficiencies due to the acidic environment. All thoses designs suffer from layer flooding or salting events which limit the durability of the cells. New cell designs and new diagnostic tools are needed to predict, diagnose, and eliminate detrimental operating regimes of CO2 electrolyzers.
In this work, we report on NiNC catalyst-based cathode GDEs for CO2 reduction to CO in a zero-gap membrane electrolyzer cell. We compare AEM and BPM cell designs. We propose the carbon crossover coefficient, CCC, as a new diagnostic analysis tool to monitor and understand through- or in-plane mass transport limitations in AEM and BPM cells. We also demonstrate how N2 bleeds can be used as diagnostic tools to recognize salting inside the electrolyzer cell.
In our AEM studies, we show that sufficient CO2 access to the catalyst surface sites is important to achieve a high performance. Under near neutral conditions on the anode we report 85% FE towards CO at 300 mA cm-2 at 3.6 V with single pass conversion of 40% which is very close to the theoretical maximum. In addition, we can report high energy efficiency but only a utilization efficiency of around 50%.
In our BPM studies, we show that NiNC GDEs are active and stable cathodes in zero-gap membrane electrolyzer. Protons raise the utilization efficiency as the carbonate will decompose into CO2 and water. To handle the changed electro osmotic water drag we replaced the ionomer with PTFE and could achieve 82% FE and 69% single pass conversion at 500 mA cm-2 with close to 100% CO2 utilization efficiency towards CO.
We show that using a either an AEM or BPM electrolyzer design we can reach over 100h stable performance at 100 mA cm-2.
Figure caption: CO2 singel pass conversion and lambda comparison of AEM and BPM CO2 reduction electrolyzer cells.

Figure 1
Electrochemical Conversion of CO2 to Fuels and Useful Chemicals over Metal Supported Solid Oxide Electrolyzers
Authors: Hu Boxun , Tucker Mike C , Park Ka-Young , Lee Taehee , Wang Wanhua , Chen Fanglin (Frank) (Frank) 
Published: August 2024

Electrochemical conversion of CO2 and H2O to fuels and chemicals provides a promising approach to simultaneously mitigate greenhouse emission and store surplus energy, which reduces electricity network variation due to increased intermittent renewable energy (such as solar and wind) utilization. Metal supported solid oxide electrolyzers (MS-SOEs) developed at Lawrence Berkeley National Laboratory provide advantages of rapid start-up, mechanical ruggedness, redox tolerance, dynamic operation, and low-cost materials. A relatively high operating temperature range of 600 to 750°C promotes energy efficiency and allows utilization of thermal energy such as steam.
In this work, efficient and stable catalysts developed at the University of South Carolina have been infiltrated in the symmetrical and porous MS-SOE architecture. The phase purity has been analyzed by X-day diffraction. The morphologies of these infiltrated and posttest catalysts have been examined by scanning electron microscopy. Optimization of cell structure, processing temperature, cell voltage, and catalyst infiltration cycles for better cell performance will be presented. The stability of MS-SOEs has been evaluated during continuous operation for >200 hours. The cell degradation mechanisms revealed by electrochemical impedance spectroscopy and high-resolution scanning electron microscopy techniques will be presented.
In addition to pure CO2 electrochemical conversion, effects of additional water and hydrogen in CO2 feedstock will be analyzed. Faradic efficiency and chemical selectivity calculated from gas chromatograph and electrochemical analyses will be presented.
Direct Non-Oxidative Methane Conversion and Hydrogen Co-Production in a Proton Conducting Membrane Reactor
Authors: Tang Qiming , Saqib Muhammad , Anjum Aniqa , Duncan Keith , Wachsman Eric D 
Published: August 2024

Direct Non-oxidation Methane Conversion (DMNC) has been recognized a promising technology for the upgrading of cheap and abundant methane to higher hydrocarbons (C2+) and H2, but this technology has not been commercialized yet because of the low methane equilibrium conversion and severe carbon deposition.1-3 Here, we present our effort to develop a proton conducting membrane reactor (SrCe0.7Zr0.2Eu0.1O3-
ⴃ) combined with the catalysts (Fe©SiO2) to circumvent the equilibrium limitations of the DMNC reaction and solve the coking (i.e., solid carbon deposition) problem. By coupling the Fe©SiO2 catalysts with H2 permeable membrane reactor, part of produced H2 during the catalytic conversion can be extracted from the effluent gas, which not only provides a one-step hydrogen production without additional separation process, but also shifts the equilibrium of the reaction to the product side and achieves an improved methane conversion and higher C2+ yield when compared to the traditional fixed-bed reactor. In addition, an air sweep outside the reactor results in O-permeation into catalyst to oxidize any deposited carbon to CO thus preventing coking.
The membranes were fabricated using tape casting of the support layer followed by dip coating process to form the dense membrane layer. Using this method, we obtained 25 µm for the thickness of the dense layer and around 700 µm for the thickness of the support layer (see Fig. 1a and 1b). The catalyst was synthesized by a simple sol-gel method followed by fusing process, and then was crushed into 40-80 mesh and loaded inside of membrane reactor to test.
The performance metrics include methane conversion, selectivity, and product yield. Our membrane reactor achieved single-pass methane conversion of 17.5%, and a C2+ yield of 15% (see Fig. 1c) at 1323K.
Finally, our membrane reactors were stable for over 350 hours, which, along with the aforementioned performance metrics, constitutes a major advance in the development of commercial DMNC technology.

References

Guo, X.; Fang, G.; Li, G.; Ma, H.; Fan, H.; Yu, L.; Ma, C.; Wu, X.; Deng, D.; Wei, M.; Tan, D.; Si, R.; Zhang, S.; Li, J.; Sun, L.; Tang, Z.; Pan, X.; Bao, X., Direct Nonoxidative Conversion of Methane to Ethylene, Aromatics, and Hydrogen. Science
2014,
344 (6184), 616-619.

Thyssen, V. V.; Vilela, V. B.; de Florio, D. Z.; Ferlauto, A. S.; Fonseca, F. C., Direct Conversion of Methane to C2 Hydrocarbons in Solid-State Membrane Reactors at High Temperatures. Chemical Reviews
2022,
122 (3), 3966-3995.

Sakbodin, M.; Schulman, E.; Cheng, S.; Huang, Y.-L.; Pan, Y.; Albertus, P.; Wachsman, E. D.; Liu, D., Direct Nonoxidative Methane Conversion in an Autothermal Hydrogen-Permeable Membrane Reactor. Advanced Energy Materials
2021,
11 (46), 2102782.

Figure 1
Integrated Experiment-Theory Framework for Studying Mass Transport Effects in Electrochemical CO2 Reduction on Copper
Authors: Matthews Jesse E , Govindarajan Nitish , Varley Joel , Guo Jack , Ehlinger Victoria Marie , Roy Thomas , Chu An , Cho Ara , Pedersen Frank Abild , Bajdich Michal , Lee Dong Un (Daniel) , Lin Tiras Y , Hahn Christopher , Jaramillo Thomas F. 
Published: August 2024

Electrochemical carbon dioxide reduction (eCO2R) has emerged as a promising approach to produce high-value fuels and chemicals using renewable energy sources. In particular, Cu catalysts can convert CO2 to a wide range of hydrocarbon and oxygenate products, including CO, formate, ethanol and ethylene. However, the activity and selectivity of eCO2R is highly dependent on mass transport and the corresponding reaction microenvironment present under operating conditions. In this talk, we present an integrated framework that combines experiments with computational fluid dynamics (CFD) and density functional theory (DFT) based microkinetic modeling to predict the effect of varying mass transport on eCO2R in a custom-designed flow cell. The flow cell is designed with multiple electrolyte jets impinging onto the electrocatalyst surface for rapid and homogeneous reactant transport. We first demonstrate the effect of mass transport in a flow cell architecture by controlling the flow rate of CO2-saturated 0.1 M KHCO3 to a Cu electrocatalyst. Significant increases in the production rates of formate and CO are observed with increasing flow rate, as well as an enhancement in multi-carbon products at high overpotentials. Increasing flow rate promotes hydrogen evolution at low overpotentials but has little effect at large overpotentials, suggesting a transition from HCO3
- to water as the dominant proton donor with increasing overpotential. CFD simulations are employed to model the distribution of boundary layer thicknesses within the flow cell, which subsequently set the boundary conditions for the coupled 1D transport-microkinetic model. The calculated boundary layer thickness values are corroborated by experimentally measured transport-limited currents. Our model successfully predicts experimentally observed trends in selectivity with mass transport, such as an increase in the production of ethylene and ethanol at high flow rates due to enhanced CO2 transport. The slight suppression of hydrogen reduction at higher flow rates due to an increase in *CO coverage is also predicted and supported by experimental results. This work demonstrates the importance of incorporating transport processes in the CFD-DFT coupled modeling of device performance for electrochemical CO2 reduction.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL release number: LLNL-ABS-857566.
How Mechanical Challenges Affect the Performance of Industrial Scale Carbon Dioxide Electrolyzer Cells?
Authors: Kecsenovity Egon , Hursán Dorottya , Janáky Csaba 
Published: August 2024

One of the most important challenge of humanity in the mid-21st century is to maintain economic growth in an environmentally sustainable way. The European Green Deal addresses this issue, and it aims at making Europe climate neutral by 2050. To reach this aim, a promising technology is to convert a greenhouse gas, carbon dioxide into valuable chemicals (produce e.g., energy carriers, fine chemicals, pharmaceuticals) in an environmentally and economically sustainable manner, such as the utilization of renewable energy sources.
The direct electrochemical reduction of carbon dioxide into carbon-monoxide (a high-value product which can be readily used in the chemical value chain) is a promising waste-to-wealth approach among the developed technologies and it can be easily coupled with carbon-free electricity sources to make the process completely sustainable. Novel catalysts, electrode assemblies, and cell configurations are all necessary to achieve economically appealing performance, as well as finding technological solutions that enable scale-up to reach industrially relevant dimensions.
Zero-gap electrolyzer cell technology operates with high reaction rates and good efficiencies under ambient and near ambient conditions. In addition, its operation is simpler compared to other types of carbon-dioxide electrolyzer cell technologies (just one example: there is no need very precisely pressure control because no flowing catholyte inside the cell), and this allows the scale up of such architectures. Exploring the fundamentals and understanding of the chemistry in zero-gap electrochemical cells is carried out by many research groups, usually with small experimental test cells. These results provide a good scientific basis (e.g., to select the right catalysts, components, or to study long-term degradation, etc.), however, compared to the size of an industrial-scale electrolyzer, these experimental cells only measure a "one point" chemistry. The results cannot be transferred without careful consideration during scale-up, due to several additional challenges. These challenges are mainly of mechanical origin, and all of these create uneven conditions that can significantly affect the chemistry of the on given sections of the cells.
Over the past several years, we have gone through the steps of scaling up electrochemical cells (for CO2-to-CO conversion) from a small experimental test cell (8 cm2) to an industrial-sized cell stack (2500 cm2 / cell). During the development journey we encountered many of the challenges outlined above. In this talk, I am going to present some of these challenges, their origins, what affects them and by them, and what principles can be used to find solutions.
Electrodes Modified with Overlayers for Enhanced CO2 Reduction Selectivity
Authors: Barile Christopher J. 
Published: August 2024

Like many electrocatalytic reactions involving the transfer of multiple protons and electrons, the CO2 reduction reaction frequently exhibits poor selectivity among many possible products. In this presentation, I will describe our laboratory’s efforts to design electrochemical platforms that enable the control over proton transfer dynamics to electrocatalysts using molecular and polymeric overlayers with the goal of increasing product selectivity and understanding reaction mechanism. This platform is generally applicable to both molecular and metallic systems, and we demonstrate how it can be used to improve the selectivity of nonprecious metal O2 reduction and NO3
- reduction catalysts.
For the CO2 reduction reaction, this strategy as applied to metal electrodes is also broadly germane and is used to modulate catalyst reactivity such that it results in the selective production of ethylene, ethanol, methanol, carbon monoxide, and methane, with examples for each with Faradaic efficiencies in excess of 70%. A common theme is that the hydrophobicity of the metal-overlayer interface frequently controls product selectivity and can steer the site of protonation events at intermediates. In this manner, for example, the selectivity of catalysts between the C2 products ethanol and ethylene can be dictated. To aid in mechanistic understanding and catalyst characterization, the majority of these studies are conducted on nominally flat metal electrodes. However, we will also describe ongoing efforts to nanostructure these CO2 reduction systems to develop selective catalysts that operate at high current densities.
Impact of Pulsed Currents on Zero-Gap Cu-Reduction of CO2 to Ethylene
Authors: Marufu Michell , Goldman Maxwell , Prajapati Aditya , Baker Sarah , Clemens Auston L. , Krall Eric , Hahn Christopher , Duoss Eric B 
Published: August 2024

The electrochemical reduction of CO2 provides a sustainable route to produce key building blocks in the petrochemical and manufacturing industries, thereby reducing carbon emissions and dependence on non-renewable sources. Zero gap electrolyzers are more energy efficient compared to traditional electrolyzers due to significant reduction in ohmic losses. However, the challenge of salting out limits the lifetimes of high performance zero gap electrolyzers to a few hours, hindering their adoption into industry.
Pulsed currents have been shown to increase the electrochemical stability of copper-based electrodes during the electrochemical CO2 reduction reaction (CO2RR). High operating current provides favorable CO2RR product efficiencies, but also increases the salt crossover from the anolyte to the cathode where the salt precipitation may lead to blocking the CO2 flow fields causing the electrolyzer to fail. We demonstrate an operating protocol that incorporates a short period of lower current which reduces CO2 consumption and allows for dissolution of carbonate salt on the cathode surface by reducing cation crossover. This is followed by a higher current to maximize CO2RR products. Intermittent pulsing reverses some of the carbonate salt production at the cathode, which allows the electrolyzer cell to restore itself, thereby increasing lifetime. The method is demonstrated in a 5cm2 zero-gap cell, with KOH, CsOH and CsHCO3 to establish the extent of this method’s utility with different cations and the effect of solubility limits on this salting behavior. By employing this pulsing protocol, we observe significantly increased cell lifetimes at a high current density of 200mA/cm2.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore
National Laboratory under Contract DE-AC52-07NA27344.
LLNL-ABS-847304
Electrochemical Conversion of Bicarbonate Using Proton Exchange Membrane-Based Electrolyzer
Authors: Jeong Hui-Yun , Hahn Christopher 
Published: August 2024

Direct electrochemical conversion of captured carbon dioxide (CO2) is gaining interest as an efficient method for capturing and utilizing CO2, eliminating the need for energy-intensive CO2 separation process.[1] The integrated electrolyzer with bicarbonate feed operates on the principle of spontaneous reduction of CO2 released from bicarbonate within the electrolyzer. The key to the on-site decomposition of bicarbonate into CO2 is to acidify the bicarbonate within the electrolyzer through the deliberately generated pH gradient. Bipolar membrane has been extensively used to generate pH gradient and acidify the bicarbonate feed.[2] However, the high ionic resistivity of bipolar membrane and slow kinetic of water dissociation reaction can result in a high operation cell voltage.
In this study, we demonstrate proton exchange membrane based-bicarbonate electrolyzer which produces carbon monoxide from bicarbonate feedstock with high CO production selectivity and low cell voltage that are comparable to the conventional gas fed CO2 electrolyzer. To achieve highly selective CO production selectivity, a nickel single atom catalyst (Ni SAC) where the atomically dispersed nickel active sites decorated on the nitrogen doped carbon was prepared and utilized. Ni-SAC showed high CO production selectivity even in bicarbonate feed electrolyzer. To further improve the performance of this integrated electrolyzer, significant attention was given to the optimization of electrode structures. Due to the complexity of the reaction environment within the integrated electrolzyer, the performance of the electrolyzer is heavily dependent on the porosity of electrodes and distribution of catalyst on the electrodes. By optimizing the fabrication of electrodes with Ni-SACs, the optimal catalyst coated electrode showed high CO production selectivity over 90% with current density of 100 mA/cm2 at low operating cell potential of 3 V.
References
[1] M. C. Freyman, Z. Huang, D. Ravikumar, E. B. Duoss, Y. Li, S. E. Baker, S. H. Pang and J. A. Schaidle, Joule, 2023, 7, 631-651.
[2] T. Li, E. W. Lees, M. Goldman, D. A. Salvatore, D. M. Weekes and C. P. Berlinguette, Joule, 2019, 3, 1487-1497.
Thin Film Based Membrane Electrode Assemblies for Solid-State Ammonia Synthesis
Authors: Wallis Jan , Ravkina Olga , Surkus Annette-Enrica , von Mallinckrodt Robin , Mewafy Basma , Wartmann Jens , Kruth Angela 
Published: August 2024

Ammonia is the of the most crucial chemicals and currently primarily produced through the Haber-Bosch process causing the industrial ammonia production to emit more CO2 than any other chemical-making reaction. While the current primary function of ammonia lies within the fertilizer production, it can also be directly used as a fuel for power generation or in the maritime industry. Compared to hydrogen, ammonia has superior storage and transportation capabilities due to its greater volumetric energy density and mild conditions for liquefication. Given the need of reducing global carbon emissions, ammonia could be synthesized electrochemically using air, water and electricity by the Solid-State Ammonia Synthesis (SSAS). Protonic ceramic cells operate within an intermediate temperature regime of around 450 - 550 °C which is well suited for this process. Within our work, we present a tubular membrane electrode unit entirely made of ceramic components based on a barium zirconate thin film electrolyte. An ammonia production rate of 9.06 × 10-10 mol s-1 cm-2 and a Faradaicefficiency of 6.58% were achieved using a NiO-BaZr0.7Ce0.2Y0.1O3-
δ
| BaZr0.8Y0.2O3-
δ
| Ru@Ba0.5Sr0.5TiO3-δ cell.
A key innovation lies in the production of dense BaZr0.8Y0.2O3-δ electrolyte layers, ranging from 1 to 5 µm in thickness, utilizing a Closed-Field Unbalanced Magnetron Sputtering (CFUMS) process. This technique allows precise adjustments of stoichiometric ratios within the perovskite structure, offering improved sputtering yields compared to conventional methods. Furthermore, the crystallinity, phase purity, and microstructure of sputter-deposited thin films are enhanced through selective laser annealing (SLA), resulting in high-density films composed of single-phase BaZr0.8Y0.2O3-δ with average crystallite sizes of 200 nm while avoiding substrate damage from thermal stress. Electrochemical performance was evaluated through impedance spectroscopy, half-cell tests and full cell tests providing insights into the efficacy of the developed tubular membrane reactor for the electrochemical synthesis of ammonia. The results demonstrate the feasibility of utilizing ceramic proton conductors in SSAS, particularly highlighting the potential of high-pressure operation up to 80 bars in tubular cells at relatively low temperatures around 450 °C, thereby achieving attractive NH3 production rates.
This research contributes to the evolving landscape of sustainable ammonia synthesis by presenting a novel approach that integrates advanced materials and manufacturing techniques. Electrification and decentralization of the ammonia supply chain will expand the market by supporting its current use as fertilizer source and enable a new route as green energy carrier paving the way for an ammonia-based economy.

Figure 1