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Perovskite oxides show great promise as an alternative catalyst to the conventional nickel cermets for CO2 reduction reactions (CO2RR) in solid oxide electrolysis cells (SOECs) owing to their advantages of redox stability and coking resistance. Nevertheless, practical applications of these oxides are prevented largely by their poor CO2RR activities. Herein, a novel donor and acceptor co‐doped nonstoichiometric double perovskite, La0.3Sr1.55Fe1.5Ni0.1Mo0.4O6−δ (LSFNM), is developed with in situ exsolved FeNi3 nanoparticles to efficiently catalyze CO2RR in SOECs. Pure CO2 electrolysis over the impregnated FeNi3@LSFNM catalysts is evaluated on two types of SOECs—one with thin (ZrO2)0.89(Sc2O3)0.1(CeO2)0.01 (SSZ) electrolytes supported on 430L alloys and the other with thin La0.9Sr0.1Ga0.8Mg0.2O3−δ (LSGM) electrolytes supported on impregnated SmBa0.5Sr0.5Co2O5+δ (SBSCO)@LSGM anodes, producing unprecedently high current densities of 2.84 A cm−2 for the former and 3.07 A cm−2 for the latter at 1.5 V and 800 °C. Experimental analysis and density‐functional theory (DFT) calculations reveal collective synergistic catalysis of oxygen vacancies (VO..${V}_{\mathrm{O}}^{..}$), the doping Ni2+ ions and FeNi3 nanoparticles via the cooperative VO..${V}_{\mathrm{O}}^{..}$‐O(CO2), and Ni(II)–C(sp) and Ni(0)–O(CO2) interactions in LSFNM, not only facilitating CO2 chemisorption on oxygen vacancies but also destabilizing and dissociating surface carbonates in the vicinity of FeNi3 spontaneously into CO. [ABSTRACT FROM AUTHOR]

Recent progresses have highlighted the enormous potentials of renewable electricities driven carbon dioxide (CO2) electrolysis in achieving carbon neutrality. However, its further industrial application is limited by low liquid product concentrations, which requires energy‐intensive downstream separation processing. Herein we report a CO2 and methanol co‐electrolysis strategy to produce formate at both electrodes and collect highly concentrated formate in zero‐gap CO2 electrolyzers. An anion exchange membrane was employed to enable formate product crossover from cathode to anode. A bismuth silicate derived nanofiber electrocatalyst with rich grain boundaries was synthesized and exhibited excellent formate selectivity (Faradaic efficiency >95%), high activity (partial current density >500 mA cm−2), as well as good stability (>120 h). Coupled with NiOX anode catalyst for methanol selective oxidation to formate in a zero‐gap electrolyzer, we demonstrate a ~180% of formate Faradaic efficiency and a full‐cell voltage of 2.43 V at an industrially relevant current density of 0.2 A cm−2. By decoupling product generation and collection, our electrolyzer produced a highly concentrated formate of 3.24 M, which could be directly used as anode fuel for fuel cells. [ABSTRACT FROM AUTHOR]

The in situ exsolution technique of nanoparticles has brought new opportunities for the utilization of perovskite‐based catalysts in solid oxide cells. However, the lack of control over the structural evolution of host perovskites during the promotion of exsolution has restricted the architectural exploitation of exsolution‐facilitated perovskites. In this study, we strategically broke the long‐standing trade‐off phenomenon between promoted exsolution and suppressed phase transition via B‐site supplement, thus broadening the scope of exsolution‐facilitated perovskite materials. Using carbon dioxide electrolysis as an illustrative case study, we demonstrate that the catalytic activity and stability of perovskites with exsolved nanoparticles (P‐eNs) can be selectively enhanced by regulating the explicit phase of host perovskites, accentuating the critical role of the architectures of perovskite scaffold in catalytic reactions occurring on P‐eNs. The concept demonstrated could potentially pave the way for designing the advanced exsolution‐facilitated P‐eNs materials and unveiling a wide range of catalytic chemistry taking place on P‐eNs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon dioxide electrolysis was utilized to enhance hydrogen production performance. • A techno-economic analysis was conducted and compared with the conventional process. • Energy efficiency, economic viability, and environmental impact were all improved. • Flexibility of production is enhanced to adapt to fluctuating market conditions. • Methane leakage and carbon tax have relatively minor impact on proposed process. Conventional blue hydrogen production still leads to direct carbon emissions, as well as significant energy consumption and costs for carbon dioxide (CO 2) capture. CO 2 electrolysis, which is one of the promising carbon utilization technologies, faces challenges beyond cell performance, including downstream separation. To address these issues, this study proposes a novel hydrogen production process integrated with CO 2 electrolysis. Four integrated processes were developed based on two types of CO 2 electrolysis in which cathode separation was either included or excluded. These integrated processes eliminate atmospheric carbon emissions from fossil-fuel-based hydrogen production without requiring a carbon capture unit; furthermore, the hydrogen yield increases. These processes were evaluated in terms of energy efficiency (EE), levelized cost of hydrogen (LCOH), and process carbon emission (PCE). Among the developed processes, the high temperature CO 2 electrolysis without cathode separation (HT-CO 2 EL(w/oSep)) process exhibited the lowest LCOH and PCE. These findings demonstrate that proposed process effectively addresses the challenges associated with downstream separation and upstream heating inherent in standalone CO 2 electrolysis systems. Compared with conventional blue hydrogen production, the HT-CO 2 EL(w/oSep) process achieved 22.2% improvement in EE, 12.0% reduction in LCOH, and 82.0% decrease in PCE. Sensitivity analysis shows that the proposed process remains economically viable compared to conventional blue and green hydrogen and is more adaptable to market fluctuations. The improvement in cell performance is expected to contribute to cost savings. Even accounting for methane leakage and carbon taxes, the process shows only a modest increase in total carbon emissions and LCOH. [ABSTRACT FROM AUTHOR]

One way to avoid CO2 pollution is changing it into CO by solid oxide electrolyzers, in which doped SrTiO3 can be used as cathode materials. It is found that in situ exsolved Ni nanoparticles in doped SrTiO3 cathode can further improve the electrolysis performance. In this work, (La0.2Sr0.8)0.85Ti0.8Cr0.1Ni0.1O3−δ cathode with in situ exsolved Ni particles is investigated. A new model proposed explains the influence of exsolution process on crystal structure. Based on thermogravimetric analysis, it is estimated that about 13.6% to 37.4% Ni atoms exsolve out of original cathode. With the new cathode containing Ni nanoparticles, the yield of CO from electrolysis is improved at about 50% and the current efficiency is increased at about 10%. [ABSTRACT FROM AUTHOR]

This study describes a world of new carbon “fullerene” allotropes that may be synthesized by molten carbonate electrolysis using greenhouse CO2 as the reactant. Beyond the world of conventional diamond, graphite and buckyballs, a vast array of unique nanocarbon structures exist. Until recently, CO2 was thought to be unreactive. Here, we show that CO2 can be transformed into distinct nano-bamboo, nano-pearl, nano-dragon, solid and hollow nano-onion, nano-tree, nano-rod, nano-belt and nano-flower morphologies of carbon. The capability to produce these allotropes at high purity by a straightforward electrolysis, analogous to aluminum production splitting of aluminum oxide, but instead nanocarbon production by splitting CO2, opens an array of inexpensive unique materials with exciting new high strength, electrical and thermal conductivity, flexibility, charge storage, lubricant and robustness properties. Commercial production technology of nanocarbons had been chemical vapor deposition, which is ten-fold more expensive, generally requires metallo-organics reactants and has a highly carbon-positive rather than carbon-negative footprint. Different nanocarbon structures were prepared electrochemically by variation of anode and cathode composition and architecture, electrolyte composition, pre-electrolysis processing and current ramping and current density. Individual allotrope structures and initial growth mechanisms are explored by SEM, TEM, HAADF EDX, XRD and Raman spectroscopy.

The electrolysis of CO2 in molten carbonate has been introduced as an alternative mechanism to synthesize carbon nanomaterials inexpensively at high yield. Until recently, CO2 was thought to be unreactive, making its removal a challenge. CO2 is the main cause of anthropogenic global warming and its utilization and transformation into a stable, valuable material provides an incentivized pathway to mitigate climate change. This study focuses on controlled electrochemical conditions in molten lithium carbonate to split CO2 absorbed from the atmosphere into carbon nanotubes (CNTs), and into various macroscopic assemblies of CNTs, which may be useful for nano-filtration. Different CNT morphologies were prepared electrochemically by variation of the anode and cathode composition and architecture, variation of the electrolyte composition pre-electrolysis processing, and variation of the current application and current density. Individual CNT morphologies’ structures and the CNT molten carbonate growth mechanisms are explored using SEM (scanning electron microscopy), TEM (transmission electron micrsocopy), HAADF (high angle annular dark field), EDX (energy dispersive xray), X-ray diffraction), and Raman methods. The principle commercial technology for CNT production had been chemical vapor deposition, which is an order of magnitude more expensive, generally requires metallo-organics, rather than CO2 as reactants, and can be highly energy and CO2 emission intensive (carries a high carbon positive, rather than negative, footprint).

Electroreduction of carbon dioxide (CO2) to carbon monoxide (CO) via a solid oxide electrolysis cell, simplified as CO2RR, is now attracting more and more attention because it can effectively utilize greenhouse gas and efficiently convert surplus electrical energy into chemical energy. In this work, a stable cathode material Pr0.4Sr0.6Fe0.875Mo0.125O3-δ (PSFM), which can be transferred to metallic Fe nanoparticles--structured PSFM (Fe@PSFM) cathode through the in situ exsolution method, has been successfully prepared for CO2RR application, and exhibits a considerable electrolysis current density of 0.71 A cm-2 with good stability when operated at 800 °C and 1.5 V. It is demonstrated that a critical applied voltage is needed for initiating the in situ exsolution of metallic Fe nanoparticles, which can effectively accelerate the CO2 adsorption, dissociation ionization, and surface diffusion to three phase boundaries (TPBs) processes. These results indicate that PSFM is a promising cathode candidate for CO2RR application because of its good electrochemical performance and stability. The findings can guide the development of other ceramic nanostructured electrode decorated with in situ exsolved metallic nanoparticles for energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

Controlled catalytic synthesis of technologically valuable carbon nanomaterials by the electrochemical capture and conversion of CO 2 is bottlenecked by limited understanding of combined electrochemical and catalytic mechanisms at play during conversion. Here, our findings provide new insight that a key factor for the electrochemical two-electrode catalytic growth of carbon nanotubes (CNTs) on the cathode surface is the oxygen evolution activity (OEA) occurring at the anode. Poor OEA can inhibit catalytic CNT formation altogether, while increased anode OEA is correlated to changes in diameter and crystallinity of CNTs with otherwise identical cathode catalyst layers and synthesis conditions. Specifically, comparing Cu, Ni/Al 2 O 3 , and Pt anodes with Fe/stainless steel cathodes we observe over 6x smaller CNT diameter distribution and over 2x lower D/G ratio when using Pt anodes with the highest OEA. This is attributed to the role of transport between the cathode and anode during synthesis; in the case of poor anode OEA, a build-up of oxide species near the cathode surface influences the surface tension at the catalyst-carbonate interface to modify CNT diameter and properties. This mechanistic insight opens the door to routes to controllably produce high quality carbon nanomaterials from the electrochemical capture and conversion of carbon dioxide. Image 1 [ABSTRACT FROM AUTHOR]

In situ exsolution of metal nanoparticles in perovskite under reducing atmosphere is employed to generate a highly active metal–oxide interface for CO2 electrolysis in a solid oxide electrolysis cell. Atomic‐scale insight is provided into the exsolution of CoFe alloy nanoparticles in La0.4Sr0.6Co0.2Fe0.7Mo0.1O3−δ (LSCFM) by in situ scanning transmission electron microscopy (STEM) with energy‐dispersive X‐ray spectroscopy and DFT calculations. The doped Mo atoms occupy B sites of LSCFM, which increases the segregation energy of Co and Fe ions at B sites and improves the structural stability of LSCFM under a reducing atmosphere. In situ STEM measurements visualized sequential exsolution of Co and Fe ions, formation of CoFe alloy nanoparticles, and reversible exsolution and dissolution of CoFe alloy nanoparticles in LSCFM. The metal–oxide interface improves CO2 adsorption and activation, showing a higher CO2 electrolysis performance than the LSCFM counterparts. [ABSTRACT FROM AUTHOR]

• CO 2 is transformed to valuable graphene incentivizing use of this greenhouse gas by a two-step process. • CO 2 is 1st transformed by molten carbonate electrolysis to carbon nanoplatelets, either directly from the air, or smokestack or pure CO 2. • Carbon nanoplatelets are produced at high yield by control of transition metals and applied electrolysis current • In the 2nd step, the carbon nanoplatelet electrodes is cooled and used "as is" as an electrochemical exfoliation electrode producing graphene • In addition to graphene, a secondary product of the CO 2 electrolysis is O 2 The deployment of graphene has been slow due to its high cost and high carbon footprint. A low carbon footprint, inexpensive synthesis of graphene, consuming rather than emitting CO 2 , is introduced to overcome these obstacles. This is accomplished here by direct molten carbonate electrolytic splitting of the greenhouse gas CO 2 to a nano-thin carbon product (carbon nanoplatelets) comprised of 25–125 graphene layers, and subsequent electrochemical exfoliation of the nanoplatelets to graphene in a carbonate soluble aqueous solution. The sole products of the carbon dioxide electrolysis are straightforward: high yield carbon nanoplatelets and oxygen. The carbon nano platelets provides a thinner starting point than a conventional graphite reactant to facilitate electrochemical exfoliation. The resultant valuable product (graphene) incentivizes utilization of the greenhouse gas carbon dioxide. [ABSTRACT FROM AUTHOR]

Highlights • SOEC with reduced LSFN as cathode and LSFN as anode for pure CO 2 electrolysis. • Cell with R-LSFN cathode shows current density of 1.42 A/cm2 at 2.0 V under 850 °C. • Synergistic effect of the in-situ exsolved Ni-Fe and oxygen vacancies is beneficial. Abstract Symmetrical solid oxide electrolysis cells have attracted increasingly attention because of their structural advantages as well as low cost. Herein, we demonstrate a novel quasi-symmetrical solid oxide electrolysis cell with reduced La 0.6 Sr 0.4 Fe 0.8 Ni 0.2 O 3- δ as cathode and La 0.6 Sr 0.4 Fe 0.8 Ni 0.2 O 3- δ as anode for pure CO 2 electrolysis. After reduction, alloy nanoparticles are in-situ exsolved and oxygen vacancies are formed in La 0.6 Sr 0.4 Fe 0.8 Ni 0.2 O 3- δ lattices. The cell with reduced La 0.6 Sr 0.4 Fe 0.8 Ni 0.2 O 3- δ cathode shows current density of 1.42 A/cm2 at 2.0 V under 850 °C for CO 2 electrolysis, with lower polarization resistance (0.06 Ω·cm2), higher Faraday efficiency (98%) and better long-term stability compared to the cell with La 0.6 Sr 0.4 Fe 0.8 Ni 0.2 O 3- δ cathode at 850 °C. The enhancement mechanism can be ascribed to the synergistic effect of the in-situ exsolved Ni-Fe nanoparticles and oxygen vacancies. The results illustrate that the quasi-symmetrical solid oxide electrolysis cells with reduced La 0.6 Sr 0.4 Fe 0.8 Ni 0.2 O 3- δ cathode demonstrate promising application for CO 2 electrolysis. [ABSTRACT FROM AUTHOR]

• The ECSA using metal UPD or bilayer capacitance was evaluated. • The ECSA area does not always correlate with particle size and cell performance. • Graphitization decreased the ECSA and affected larger than the hydrophilization. Synthesizing useful chemicals by electrolysis of carbon dioxide (CO 2) is considered a crucial strategy for recycling CO 2 in a carbon–neutral and green manner. However, generally, the catalysts used for CO 2 electrolysis have low activity, stability, and product selectivity. Herein, we evaluated the effect of the surface area, determined by electrochemical methods, on the performance of a CO 2 electrolysis cell using an anionic electrolyte membrane electrode assembly (MEA). The electrochemical surface area (ECSA) of the active metals supported on the carbon of the cathode side catalyst layer was analyzed via copper underpotential deposition (Cu-UPD) and cyclic voltammetry (CV). The ECSA was multiplied by a factor of approximately 0.6 when the particle size was increased from 2 nm to 4 nm. However, it increased by a factor of approximately 2 for Cu-UPD and no change for CV when particle size changed from 4 nm to 12 nm. The performance was evaluated using a CO 2 electrolysis zero-gap cell with an anionic electrolyte MEA. The ECSA was correlated to Faraday's efficiency in CO and H 2 production during CO 2 electrolysis. However, the ECSA measured by the electrical double-layer capability showed a lower correlation with Faraday efficiency when particle size changed from 4 nm to 12 nm. The findings obtained in this study provide guidelines for improving the catalytic performance of CO2 electrolysis cells using anionic electrolyte MEAs, and these results will promote efforts toward achieving carbon neutrality. [ABSTRACT FROM AUTHOR]

Composite cathode based on La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3− δ (LSCM) can be used for direct carbon dioxide electrolysis without a flow of reducing gas over it in an oxide-ion-conducting solid oxide electrolyzer; however, the insufficient electro-catalytic activity of LSCM electrode still restricts electrode performance and Faraday current efficiency. In this work, catalytic-active copper nanoparticles are grown on the surface of LSCM cathode via in-situ exsolution of copper metal from A-site deficient and B-site excess (La 0.75 Sr 0.25 ) 0.9 (Cr 0.5 Mn 0.5 ) 0.9 Cu 0.1 O 3− δ (LSCMC) after reduction. XRD, SEM, EDS and XPS results together confirm the reversible exsolution of copper nanocatalyst on the surface of LSCM. Carbon dioxide adsorption/desorption of LSCM is investigated. The electrical properties of reduced LSCMC are investigated and correlated to the electrochemical performance of the composite electrodes. The current efficiencies of approximately 85% are obtained with LSCM cathode decorated with copper nanocatalyst for direct carbon dioxide electrolysis in an oxide-ion-conducting solid oxide electrolyzer. [ABSTRACT FROM AUTHOR]

Zn−CO 2 batteries hold great promise for carbon-neutral and electricity generation simultaneously, whereas the main obstacle is the development of electrocatalysts with high activity and durability towards CO 2 reduction reaction (CRR). Herein, we design atomically dispersed Bi clusters supported on hollow carbon spheres (BiC/HCS) for effectively reducing CO 2 to formate, which shows the highest faradaic efficiency of 97 ± 2% at − 0.6 V vs RHE, being comparable to the previously best reported values of Bi-based materials. Experimental and theoretical analyses reveal that the atomic-level Bi x clusters not only enable high CO 2 adsorption but also stabilize the key *HCOO intermediate with a low free energy barrier. Further, an assembled rechargeable Zn−CO 2 battery with BiC/HCS as the cathode achieves a peak power density of 7.2 ± 0.5 mW cm−2 as well as an impressive rechargeability of 200 cycles. This work provides a promising alternative for CO 2 utilization and energy storage by Zn−CO 2 batteries. Graphical Abstract Bi clusters anchored on hollow carbon spheres have developed as an excellent cathode for Zn−CO 2 battery. The catalyst presents a maximal formate faradaic efficiency of 97 ± 2% at − 0.6 V vs RHE as well as good durability. The assembled Zn−CO 2 battery achieves a peak power density of 7.2 ± 0.5 mW cm−2 and energy efficiency of 68.9% (@ 3 mA cm−2), and a more than 200 cycle rechargeability. [Display omitted] • Efficient and selective electrocatalytic reduction of CO 2 to CO is achieved on Bi x clusters. • The Bi x clusters achieve a maximal CO Faradaic efficiency of 96% at − 0.6 V vs RHE and remain stable for 60 h. • The as-assembled Zn-CO 2 battery shows a peak power density of 7.0 mW cm−2 and a good cycling durability. • DFT results reveal that Bi x clusters can stabilize the key *HCOO intermediate and supress the hydrogen evolution as well. [ABSTRACT FROM AUTHOR]

This work details an in-house 2D electrochemical and thermal model of solid oxide electrolysis cell (SOEC) dedicated to the simultaneous electrolysis of steam and carbon dioxide. The apparent exchange current densities for both H2O and CO2 electrochemical reductions have been fitted on single electrolysis polarization curves obtained on a standard cathode supported cell (CSC). By using these values, predictive simulations have been performed in a co-electrolysis mode. The results have been compared to experimental data obtained in the same conditions. A good agreement is found between the simulated points and the experimental polarization curves, meaning that the model stands to predict accurately the SOEC response in co-electrolysis mode. Simulations have been performed to investigate co-electrolysis mechanisms in terms of partial pressures, current densities, and overpotentials distributions along the cell. The relative influence of both water gas shift (WGS) reaction and CO2 electrolysis on the global CO production is also discussed. [ABSTRACT FROM AUTHOR]

The electrolysis of CO2 in molten carbonate has been introduced as an alternative mechanism to synthesize carbon nanomaterials inexpensively at high yield. Until recently, CO2 was thought to be unreactive, making its removal a challenge. CO2 is the main cause of anthropogenic global warming and its utilization and transformation into a stable, valuable material provides an incentivized pathway to mitigate climate change. This study focuses on controlled electrochemical conditions in molten lithium carbonate to split CO2 absorbed from the atmosphere into carbon nanotubes (CNTs), and into various macroscopic assemblies of CNTs, which may be useful for nano-filtration. Different CNT morphologies were prepared electrochemically by variation of the anode and cathode composition and architecture, variation of the electrolyte composition pre-electrolysis processing, and variation of the current application and current density. Individual CNT morphologies' structures and the CNT molten carbonate growth mechanisms are explored using SEM (scanning electron microscopy), TEM (transmission electron micrsocopy), HAADF (high angle annular dark field), EDX (energy dispersive xray), X-ray diffraction), and Raman methods. The principle commercial technology for CNT production had been chemical vapor deposition, which is an order of magnitude more expensive, generally requires metallo-organics, rather than CO2 as reactants, and can be highly energy and CO2 emission intensive (carries a high carbon positive, rather than negative, footprint). [ABSTRACT FROM AUTHOR]

This study describes a world of new carbon "fullerene" allotropes that may be synthesized by molten carbonate electrolysis using greenhouse CO2 as the reactant. Beyond the world of conventional diamond, graphite and buckyballs, a vast array of unique nanocarbon structures exist. Until recently, CO2 was thought to be unreactive. Here, we show that CO2 can be transformed into distinct nano-bamboo, nano-pearl, nano-dragon, solid and hollow nano-onion, nano-tree, nano-rod, nano-belt and nano-flower morphologies of carbon. The capability to produce these allotropes at high purity by a straightforward electrolysis, analogous to aluminum production splitting of aluminum oxide, but instead nanocarbon production by splitting CO2, opens an array of inexpensive unique materials with exciting new high strength, electrical and thermal conductivity, flexibility, charge storage, lubricant and robustness properties. Commercial production technology of nanocarbons had been chemical vapor deposition, which is ten-fold more expensive, generally requires metallo-organics reactants and has a highly carbon-positive rather than carbon-negative footprint. Different nanocarbon structures were prepared electrochemically by variation of anode and cathode composition and architecture, electrolyte composition, pre-electrolysis processing and current ramping and current density. Individual allotrope structures and initial growth mechanisms are explored by SEM, TEM, HAADF EDX, XRD and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

• Economic analysis was conducted for methanol synthesis through various pathways. • The economy of scale was confirmed for all pathways considered. • Lowest production cost was obtained through carbon dioxide electrolysis. • Environmental assessment was performed to identify carbon dioxide emission. • Economic and environmental feasibility of methanol synthesis was demonstrated. Methanol is emerging as the carbon dioxide utilization technology and hydrogen carrier that can produce methanol using captured carbon dioxide and hydrogen. In this study, four cases were classified as methanol production according to which pathway was used to produce hydrogen: case 1 (steam methane reforming), case 2 (coal gasification), case 3 (water electrolysis), and case 4 (direct methanol production by carbon dioxide electrolysis). To figure out the best pathway in terms of economic and environmental perspectives, itemized cost estimation, sensitivity analysis, uncertainty analysis, and carbon footprint analysis were performed for four cases of methanol production with methanol production capacities of 1, 10, 20, and 50 ton d−1. From itemized cost estimation reflecting carbon footprint analysis results, respective unit methanol production costs of 3.66, 2.99, 3.69, and 0.55 $ kg−1 were obtained for methanol production capacity of 50 ton d−1. Compared to the unit methanol production cost (0.396 $ kg−1) from fossil fuel-based production, direct methanol production has become feasible than other cases. And, from sensitivity and uncertainty analysis, the cost of reactant and electricity were major economic parameters for cases 1–3 and case 4, respectively, and the possible unit methanol production cost ranges due to the cost fluctuations in future were investigated. [ABSTRACT FROM AUTHOR]

Abstract: Solid oxide electrolyzers have attracted a great deal of interest in recent years because they can convert electrical energy into chemical energy with high efficiency. Ni/YSZ cathodes are generally utilized for high temperature electrolysis of H2O and CO2 in oxygen-ion conducting solid oxide electrolyzers; however, such electrodes can only operate under reducing conditions. In an atmosphere without a flow of reducing gas, cathodes based on La0.2Sr0.8TiO3+δ (LST) are a promising alternative. Solid Oxide Electrolyzers with LST cathodes without pre-reduction were used at 700 °C for the electrolysis of 3%H2O/97%N2 and 100%CO2, and promising polarization impedance data were obtained in both atmospheres. The electrochemical results indicated that the electrochemical reduction of the La0.2Sr0.8TiO3+δ cathode was the main process at low electrical voltages, while the electrolysis was the main process at high voltages because ion transportation in the electrolyte limited the overall efficiency. The electrolysis of H2O was determined to be more efficient than the electrolysis of CO2 under the same conditions. The Faraday efficiencies of H2O and CO2 were 85.0% and 24.7%, respectively, at 700 °C and a 2 V applied potential. [Copyright &y& Elsevier]

Abstract: The SOEC electrodes during steam (H2O) electrolysis, carbon dioxide (CO2) electrolysis, and the coelectrolysis of H2O/CO2 are investigated. The electrochemical performance of nickel–yttria stabilised zirconia (Ni–YSZ), Ni–Gd0.1Ce0.9O1.95 (Ni–GDC), and Ni/Ruthenium–GDC (Ni/Ru–GDC) hydrogen electrodes and La0.8Sr0.2MnO3−δ –YSZ (LSM–YSZ), La0.6Sr0.4Co0.8Fe0.2O3−δ (LSCF), and La0.8Sr0.2FeO3−δ (LSF) oxygen electrodes are studied to assess the losses of each electrode relative to a reference electrode. The study is performed over a range of operating conditions, including varying the ratio of H2O/H2 and CO2/CO (50/50 to 90/10), the operating temperature (550–800°C), and the applied voltage. The activity of Ni–YSZ electrodes during H2O electrolysis is significantly lower than that for H2 oxidation. Comparable activity for operating between the SOEC and solid oxide fuel cell (SOFC) modes is observed for the Ni–GDC and Ni/Ru–GDC. The overpotential of H2 electrodes during CO2 reduction increases as the CO2/CO ratio is increased from 50/50 to 90/10 and further increases when the electrode is exposed to a 100% CO2 (800°C), corresponding to the increase in the area specific resistance. The electrodes exhibit comparable performance during H2O electrolysis and coelectrolysis, while the electrode performance is lower in the CO2-electrolysis mode. The activity of all the O2 electrodes as an SOFC cathode is higher than that as SOEC anodes. Among these O2 electrodes, LSM–YSZ exhibits the nearest to symmetrical behaviour. [Copyright &y& Elsevier]

Abstract: AC impedance spectroscopy has been performed on 40 mol% gadolinia-doped ceria electrodes on yttria stabilized zirconia (YSZ) at 700–950 °C in reducing CO/CO2 atmospheres. Area-specific-resistance (ASR) values for this electrode were in the range of 0.8–37 Ω-cm2, about two orders of magnitude lower than measurements on Pt electrodes and slightly lower than data on Ni-YSZ electrodes in the literature under similar temperature and partial pressure of oxygen (P O2 ) conditions. A continuum-based model of this electrode is described and an analysis performed to extract the vacancy diffusion coefficient (D v ) and surface exchange rate coefficient () as a function of temperature and P O2 , from the impedance results. The Dv data agree reasonably well with published measurements of the tracer diffusion coefficient (D ⁎) based on isotope profiling by secondary ion mass spectroscopy (SIMS) and conductivity measurements on 40 mol% GDC. The values are a factor of 3 lower than the published measurements of the surface reaction rate (k) obtained from isothermal thermogravimetric relaxation, and decrease with increasing P O2 . Values of the thermodynamic factor (A) calculated from the fitted model parameters matched well with those calculated from oxygen non-stoichiometry data in the literature. [Copyright &y& Elsevier]

Emerging Fe bonded with heteroatom P in carbon matrix (FePC) holds great promise for electrochemical catalysis, but the design of highly active and cost-efficient FePC structure for the electrocatalytic CO 2 reduction reaction (CO 2 RR) and aqueous ZnCO 2 batteries (ZCBs) is still challenging. Herein, polyhedron-shaped bifunctional electrocatalysts, FeP nanocrystals anchored in N-doped carbon polyhedrons (Fe-P@NCPs), toward a reversible aqueous ZnCO 2 battery, are reported. The Fe-P@NCPs are synthesized through a facile strategy by using self-templated zeolitic imidazolate frameworks (ZIFs), followed by an in situ high-temperature calcination. The resultant catalysts exhibit aqueous CO 2 RR activity with a CO Faradaic efficiency up to 95% at -0.55 V versus reversible hydrogen electrode (RHE), comparable to the previously best-reported values of FeNC structure. The as-constructed ZCBs with designed Fe-P@NCPs cathode, show the peak power density of 0.85 mW cm -2 and energy density of 231.8 Wh kg -1 with a cycling durability over 500 cycles, and outstanding stability in terms of discharge voltage for 7 days. The high selectivity and efficiency of the battery are attributed to the presence of highly catalytic FeP nanocrystals in N-doped carbon matrix, which can effectively increase the number of catalytically active sites and interfacial charge-transfer conductivity, thereby improving the CO 2 RR activity., (© 2022 Wiley-VCH GmbH.)

• CO 2 is transformed to valuable magnetic carbon nanotubes incentivizing use of this greenhouse gas. • The first carbide nucleated electrolytic CO 2 splitting mechanism is introduced. • CO 2 splitting and magnetic carbon nanotube growth is facilitated by iron and nickel carbide molten carbonate electrolysis. • Magnetic carbon nanotubes have a wide range of applications in medicine and catalysis. • In addition to magnetic carbon nanotubes, a secondary product of the CO 2 electrolysis is O 2. This study demonstrates that CO 2 can be split by molten carbonate electrolysis (1) to grow magnetic carbon nanotubes (CNTs) and (2) that the process can be initiated by carbide nucleation points acting as growth catalysts. This opens the path to other similar electrochemically prepared magnetic carbon nanomaterials. Magnetic carbon nanomaterials have a variety of applications, such as in directing medical therapy to localized regions and recoverable catalysts. In the presence of an iron or nickel containing case to house the molten carbonate electrolysis, or the presence of Fe or Ni in the electrochemical components, ferromagnetic CNTs can grow at the cathode. For example, EDS elemental analysis confirms the presence of iron in the CNTs, and XRD confirms the presence of iron carbide at the CNT nucleation site. The observed interlattice spacing of 0.20 nm of the iron carbide is distinct from the observed 0.36 nm graphene lattice spacing of the CNT walls. An excess iron release can be facilitated into the electrolyte using an iron rich alloy anode, such as Incoloy. The excess iron results in graphene layer coated iron carbide nodules on the exterior of the carbon nanotube product formed at the cathode, as well as iron carbide within these CNTs as observed by SEM and TEM. [ABSTRACT FROM AUTHOR]

Pd single site-anchored La 0.5 Sr 0.5 FeO 3-δ -Ce 0.8 Sm 0.2 O 2-x (Pd-LSF(SDC)) cathode is constructed for CO 2 electrolysis in solid oxide electrolysis cells. The decoration of Pd species on LSF greatly improves CO 2 electrolysis performance with 65.7% enhancement in current density at 1.6 V compared with the LSF counterpart. Electrochemical and density functional theory calculation results suggest that the Pd species are atomically anchored on the LSF phase. The coordinatively unsaturated Pd with oxygen vacancies facilitates the CO 2 dissociative adsorption, electron transfer and mass transport, thus greatly decreases the polarization resistance of the cathode and promotes the CO 2 electrolysis performance. This work provides an effective strategy to design the supported single site catalyst for high-temperature CO 2 electrolysis. Image 1 • Pd decorated La 0.5 Sr 0.5 FeO 3-δ cathode is constructed for CO 2 electrolysis in solid oxide electrolysis cells. • The decoration of Pd species on La 0.5 Sr 0.5 FeO 3-δ cathode greatly promoted the CO 2 electrolysis performance. • Pd species are atomically anchored on La 0.5 Sr 0.5 FeO 3-δ cathode. • The coordinatively unsaturated Pd facilitates the CO 2 dissociation, electron transfer and mass transport. [ABSTRACT FROM AUTHOR]

• CO 2 electrolysis in a new solid oxide electrolysis cell was conducted. • 47.4% conversion rate of CO 2 was achieved at 1.305 V and −400 mA/cm2. • Energy conversation efficiency reached 91.4% at −400 mA/cm2 and 1.305 V. • 1910 h of CO 2 electrolysis has been operated under −300 mA/cm2. Solid oxide electrolysis cell is a highly promising technology for CO 2 electrolysis and has attracted wide attention. But the durability is insufficient by known designed structure of solid oxide electrolysis cell due to structure damage. In this work, a new flat-tube solid oxide electrolysis cell (SOEC) based on double-sided air electrodes with mechanically-strong redox properties and larger active area was proposed and applied to electrolysis of CO 2 , and its electrochemical performance and long-term durability were investigated. The results showed that the charging current density reaches −600 mA/cm2 at 1.5 V and 750 °C under H 2 /CO 2 atmosphere. The CO 2 conversion rate achieves 47.4% with energy conversation efficiency of 91.4% at the electrolysis voltage of 1.305 V under the charging current density of −400 mA/cm2, corresponding to 210 mL/min of CO production rate. This new cell architecture for CO 2 electrolysis was stable at the current density of −300 mA/cm2 for 1910 h at 750 °C with a degradation rate of 4.89%/kh. The new flat-tube solid oxide electrolysis cell is capable to conduct CO 2 electrolysis with high efficiency and long-term stability. [ABSTRACT FROM AUTHOR]

A high yield, low energy synthesis of carbon nano‐onions (CNOs) by electrolysis of CO2 in molten carbonate is presented. Carbon nano‐onions are a recently recognized, less studied morphology of carbon nanomaterials consisting of nested concentric carbon spheroids. Previously, a high yield growth of carbon nanotubes by CO2 electrolysis in molten carbonate was achieved through transition metal nucleation points on the electrolysis cathode. Here, effective low energy CNO synthesis from CO2 is achieved instead by excluding those nucleating agents from the molten carbonate growth medium resulting in a profusion of uniform CNOs, with an increasing diameter correlated to increasing growth time. CO2 transformation to valuable materials, such as CNOs, adds value to CO2 to incentivize consumption of this greenhouse pollutant. For example, CNOs are currently valued 20 000 times higher than coal. [ABSTRACT FROM AUTHOR]

In situ exsolution of metal nanoparticles in perovskite under reducing atmosphere is employed to generate a highly active metal-oxide interface for CO 2 electrolysis in a solid oxide electrolysis cell. Atomic-scale insight is provided into the exsolution of CoFe alloy nanoparticles in La 0.4 Sr 0.6 Co 0.2 Fe 0.7 Mo 0.1 O 3-δ (LSCFM) by in situ scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy and DFT calculations. The doped Mo atoms occupy B sites of LSCFM, which increases the segregation energy of Co and Fe ions at B sites and improves the structural stability of LSCFM under a reducing atmosphere. In situ STEM measurements visualized sequential exsolution of Co and Fe ions, formation of CoFe alloy nanoparticles, and reversible exsolution and dissolution of CoFe alloy nanoparticles in LSCFM. The metal-oxide interface improves CO 2 adsorption and activation, showing a higher CO 2 electrolysis performance than the LSCFM counterparts., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Reversible exsolution and dissolution of metal nanoparticles in perovskite has been investigated as an efficient strategy to improve CO 2 electrolysis performance. However, fundamental understanding with regard to the reversible exsolution and dissolution of metal nanoparticles in perovskite is still scarce. Herein, in situ exsolution and dissolution of CoFe alloy nanoparticles in Co-doped Sr 2 Fe 1.5 Mo 0.5 O 6-δ (SFMC) revealed by in situ X-ray diffraction, scanning transmission electron microscopy, environmental scanning electron microscopy, and density functional theory calculations are reported. Under a reducing atmosphere, facile exsolution of Co promotes reduction of the Fe cation to generate CoFe alloy nanoparticles in SFMC, accompanied by structure transformation from double perovskite to layered perovskite at 800 °C. Under an oxidizing atmosphere, spherical CoFe alloy nanoparticles are first oxidized to flat CoFeO x nanosheets, and then dissolved into the bulk with structure evolution from layered perovskite back to double perovskite. Electrochemically, CO 2 electrolysis performance can be retrieved during 12 redox cycles due to the regenerative ability of the CoFe alloy nanoparticles. The anchoring of the CoFe alloy nanoparticles in SFMC perovskite via reduction shows enhanced CO 2 electrolysis performance and stability compared with the parent SFMC perovskite., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)