Generating C4 Alkenes in Solid Oxide Fuel Cells via Cofeeding H2 and n-Butane Using a Selective Anode Electrocatalyst

A self-assembled composited cathode coated with dual-exsolved core-shell FeNi@FeOx nanoparticles as efficient CO2 reduction electrocatalysts

Solid oxide electrolytic cells (SOECs) enable efficient electrochemical reduction of CO2 into CO, providing a sustainable solution for greenhouse gas mitigation. Nevertheless, the scarcity of stable and highly active cathode materials for the real application of SOECs is a serious challenge. Herein, a novel self-assembled composed cathode of Ni co-doped (Pr0.5Sr0.5)0.95Fe0.9Nb0.1O3-δ-Gd0.1Ce0.9O2-δ (PSFNNb-GDC) is proposed as an efficient CO2 electrolysis. The NiFe/FeOx nanoparticles with a core-shell structure are uniformly deposited onto the surface of the PSFNNb-GDC cathode. La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM)-based single cell with NiFe/FeOx@PSFNNb-GDC cathode achieve excellent performance (1.33 A cm-2 at 850 °C@1.6 V) and stability (800 °C@1.2 V) in long-term operation. The performance enhancement original from increased surface oxygen vacancies and in situ formed FeNi@FeOx core-shell nanoparticles. This research highlights the potential of rational structural design of SOECs cathode materials in advancing the field of CO2 utilization.

Status and outlook of solid electrolyte membrane reactors for energy, chemical, and environmental applications

Solid electrolyte membrane reactors (SEMRs) can be operated at high temperatures with distinct reaction kinetics, or at lower temperatures (300-500 °C) for industrially relevant energy applications (such as solid oxide fuel/electrolysis cells, direct carbon fuel cells, and metal-air batteries), chemical (such as alkane dehydrogenation, C-C coupling, and NH3 synthesis), environmental (De-NO x , CO2 utilization, and separation), as well as their combined (one-step coupled CO2/H2O co-electrolysis and methanation reaction, power and chemical cogeneration) applications. SEMRs can efficiently integrate electrical, chemical, and thermal energy sectors, thereby circumventing thermodynamic constraints and production separation issues. They offer a promising way to achieve carbon neutrality and improve chemical manufacturing processes. This review thoroughly examines SEMRs utilizing various ionic conductors, namely O2-, H+, and hybrid types, with operations in different reactor/cell architectures (such as panel, tubular, single chamber, and porous electrolytes). The reactors operate in various modes including pumping, extraction, reversible, or electrical promoting modes, providing multiple functionalities. The discussion extends to examining critical materials for solid-state cells and catalysts essential for specific technologically important reactions, focusing on electrochemical performance, conversion efficiency, and selectivity. The review also serves as a first attempt to address the potential of process-intensified SEMRs through the integration of photo/solar, thermoelectric, and plasma energy and explores the unique phenomenon of electrochemical promotion of catalysis (EPOC) in membrane reactors. The ultimate goal is to offer insight into ongoing critical scientific and technical challenges like durability and operational cost hindering the widespread industrial implementation of SEMRs while exploring the opportunities in this rapidly growing research domain. Although still in an early stage with limited demonstrations and applications, advances in materials, catalysis science, solid-state ionics, and reactor design, as well as process intensification and/or system integration will fill the gaps in current high temperature operation of SEMRs and industrially relevant applications like sustainable clean chemical production, efficient energy conversion/storage, as well as environmental enhancement.

Performance of Solid Oxide Fuel Cells Based on Liquid Hydrocarbon Fuel Reforming Gas: Effect of Cell Structure and Gas Composition

This work comprehensively analyzed how the thickness of the anode and the fuel gas compositions can alter the durability and electrochemical performance of solid oxide fuel cells (SOFCs) when they are operated on steam-reformed gas of hydrocarbons. The electrochemical tests and surface characterizations on the tested cells indicate that cell performance degradation is primarily associated with anode carbon deposition, which increases with a higher C2 gas content in the reforming gas. Additionally, the gas flow field simulation verified that reducing the anode thickness can effectively increase the surface steam content, thereby reducing carbon deposition and improving the stability of the fuel cell. The electrochemical performance of the cell is improved by the C1 composition in the reformed gas. The presence of CO and CO2 gases promotes the adsorption of H2 on the Ni metal surface, thereby reducing the polarization resistance of the anode. Meanwhile, CH4 can release more energy during electrochemical oxidation, reducing the concentration of polarization. These results underscore the potential of utilizing reformed gases consisting of 70 vol % H2, nearly 30 vol % CO, CO2, and trace alkanes to function SOFCs. This approach may enhance power density, broaden fuel options, and provide practical solutions for the advancement and commercialization of SOFC technology.

Revolutionizing Methane Transformation with the Dual Production of Aromatics and Electricity in a Protonic Ceramic Electrocatalytic Membrane Reactor

Reducing the energy and carbon intensity of the conventional chemical processing industry can be achieved by electrochemically transforming natural gases into higher-value chemicals with higher efficiency and near-zero emissions. In this work, the direct conversion of methane to aromatics and electricity has been achieved in a protonic ceramic electrocatalytic membrane reactor through the integration of a proton-conducting membrane assembly and a trimetallic Pt-Cu/Mo/ZSM-5 catalyst for the nonoxidative methane dehydro-aromatization reaction. In this integrated system, a remarkable 15.6% single-pass methane conversion with an 11.4% benzene yield has been demonstrated, while a peak power density of 276 mW cm-2 is obtained at 700 °C. The enhanced 15.7% increase in conversion and 16.0% improvement in the yield are observed when compared with the thermochemical process, which is attributed to the shift of reaction equilibrium by the removal of hydrogen through the protonic membrane. Concurrently, the faster H2 removal at a higher electrical current gave rise to a higher methane conversion and benzene yield. Furthermore, the catalyst can be efficiently regenerated by eliminating carbon deposition. A stable cell potential is maintained for 45 h under a constant current load of 0.13 A cm-2. The dual production of aromatics and electricity in the electrocatalytic membrane reactor has been demonstrated to be an attractive approach for decarbonizing chemical processing.

A High-Entropy Layered Perovskite Coated with In Situ Exsolved Core-Shell CuFe@FeOx Nanoparticles for Efficient CO2 Electrolysis

Solid oxide electrolysis cells (SOECs) are promising energy conversion devices capable of efficiently transforming CO2 into CO, reducing CO2 emissions, and alleviating the greenhouse effect. However, the development of a suitable cathode material remains a critical challenge. Here a new SOEC cathode is reported for CO2 electrolysis consisting of high-entropy Pr0.8 Sr1.2 (CuFe)0.4 Mo0.2 Mn0.2 Nb0.2 O4-δ (HE-PSCFMMN) layered perovskite uniformly coated with in situ exsolved core-shell structured CuFe alloy@FeOx (CFA@FeO) nanoparticles. Single cells with the HE-PSCFMMN-CFA@FeO cathode exhibit a consistently high current density of 1.95 A cm-2 for CO2 reduction at 1.5 V while maintaining excellent stability for up to 200 h under 0.75 A cm-2 at 800 °C in pure CO2 . In situ X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations confirm that the exsolution of CFA@FeO nanoparticles introduces additional oxygen vacancies within HE-PSCFMMN substrate, acting as active reaction sites. More importantly, the abundant oxygen vacancies in FeOx shell, in contrast to conventional in situ exsolved nanoparticles, enable the extension of the triple-phase boundary (TPB), thereby enhancing the kinetics of CO2 adsorption, dissociation, and reduction.

High-Performance Co-production of Electricity and Light Olefins Enabled by Exsolved NiFe Alloy Nanoparticles from a Double-Perovskite Oxide Anode in Solid Oxide-Ion-Conducting Fuel Cells

Light olefins (LOs) such as ethylene and propylene are critical feedstocks for many vital chemicals that support our economy and daily life. LOs are currently mass produced via steam cracking of hydrocarbons, which is highly energy intensive and carbon polluting. Efficient, low-emission, and LO-selective conversion technologies are highly desirable. Electrochemical oxidative dehydrogenation of alkanes in oxide-ion-conducting solid oxide fuel cell (SOFC) reactors has been reported in recent years as a promising approach to produce LOs with high efficiency and yield while generating electricity. We report here an electrocatalyst that excels in the co-production. The efficient catalyst is NiFe alloy nanoparticles (NPs) exsolved from a Pr- and Ni-doped double perovskite Sr2Fe1.5Mo0.5O6 (Pr0.8Sr1.2Ni0.2Fe1.3Mo0.5O6-δ, PSNFM) matrix during SOFC operation. We show evidence that Ni is first exsolved, which triggers the following Fe-exsolution, forming the NiFe NP alloy. At the same time as the NiFe exsolution, abundant oxygen vacancies are created at the NiFe/PSNFM interface, which promotes the oxygen mobility for oxidative dehydrogenation of propane (ODHP), coking resistance, and power generation. At 750 °C, the SOFC reactor with the PSNFM catalyst reaches a propane conversion of 71.40% and LO yield of 70.91% under a current density of 0.3 A cm-2 without coking. This level of performance is unmatchable by the current thermal catalytic reactors, demonstrating the great potential of electrochemical reactors for direct hydrocarbon conversion into value-added products.

Pr-Doped SrTi0.5Mn0.5O3-δ as an Electrode Material for a Quasi-Symmetrical Solid Oxide Fuel Cell Using Methane and Propane Fuel

The use of identical electrodes for both the cathode and the anode in a symmetrical solid oxide fuel cell (SSOFC) can simplify the preparation process and increase the durability of the cell, but it is also demanding on the properties of the electrode including stability, electric conductivity, and electrocatalysis. The doping of variable-valence Mn^4+/3+2+ on the B site of stable SrTiO₃ is explored in this study as both the cathode and the anode for an SSOFC. Though the limit of Mn doping in SrTiO₃ is generally low, the additional Pr^3+/4+ donor on the Sr site of SrTi_0.5Mn_0.5O₃ was found to enhance the structure stability, electric conductivity, and electrocatalysis. The cell with Pr_0.5Sr_0.5Ti_0.5Mn_0.5O₃ electrodes excels under H₂, propane, or CH₄/H₂ fuel, providing the cocatalyst was infiltrated on the anode side. The polarization resistance value of Pr_0.5Sr_0.5Ti_0.5Mn_0.5O₃ was 0.27 Ω·cm² as the cathode and 0.33 Ω·cm² for the SSOFC using H₂ fuel. The performance under CH₄/H₂ fuel can be boosted to above 0.9 W cm^-2 if Ni/ceria was loaded onto the anode to enhance the methane reforming. This work contributes to a perovskite anode with high Mn doping in SrTiO₃ for application in SSOFC for natural gas with renewable H₂ injection.

Tuning the Catalytic Performance of Cobalt Nanoparticles by Tungsten Doping for Efficient and Selective Hydrogenation of Quinolines under Mild Conditions

Non-noble bimetallic CoW nanoparticles (NPs) partially embedded in a carbon matrix (CoW@C) have been prepared by a facile hydrothermal carbon-coating methodology followed by pyrolysis under an inert atmosphere. The bimetallic NPs, constituted by a multishell core-shell structure with a metallic Co core, a W-enriched shell involving Co7W6 alloyed structures, and small WO3 patches partially covering the surface of these NPs, have been established as excellent catalysts for the selective hydrogenation of quinolines to their corresponding 1,2,3,4-tetrahydroquinolines under mild conditions of pressure and temperature. It has been found that this bimetallic catalyst displays superior catalytic performance toward the formation of the target products than the monometallic Co@C, which can be attributed to the presence of the CoW alloyed structures.

Proton-Assisted Reconstruction of Perovskite Oxides: Toward Improved Electrocatalytic Activity

Electrocatalysis is indispensable to various emerging energy conversion and storage devices such as fuel cells and water electrolyzers. Owing to their unique physicochemical properties, perovskite oxide materials are one of the most promising water oxidation (OER) catalysts solely comprising earth-abundant elements. Nonetheless, many perovskite oxide catalysts suffer from a number of inherent problems such as the A-site cation segregation on the surface, coarse particles due to agglomeration/sintering, and surface decomposition during catalytic reactions. Besides, the catalytic activity is often incomparable with those of the state-of-the-art catalysts. In this work, we developed a proton-assisted approach to mitigate these common challenges. The protonation via the interaction of oxygen vacancies and water molecules induced the formation of protonic defects and the lattice expansion of the perovskite, leading to the fracture of big particles to yield small nanoparticles. This hydration in an acidic solution also selectively removed the A-site cation segregates and generated a spinel/perovskite heterostructure on the surface. We verified this approach using three typical perovskite OER catalysts including Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF), La_0.6Sr_0.4Co_0.8Fe_0.2O₃ (LSCF), and La_0.75Sr_0.25MnO₃ (LSM). The processed catalysts showed much improved activity while maintaining their excellent stability, surpassing most of today's OER catalysts based on complex oxides.

A Direct n-Butane Solid Oxide Fuel Cell Using Ba(Zr0.1Ce0.7Y0.1Yb0.1)0.9Ni0.05Ru0.05O3-δ Perovskite as the Reforming Layer

Hydrocarbon-fueled solid oxide fuel cells (SOFCs) that can operate in the intermediate temperature range of 500-700 °C represent an attractive SOFC device for combined heat and power applications in the industrial market. One of the ways to realize such a device relies upon exploiting an in situ steam reforming process in the anode catalyzed by an anti-carbon coking catalyst. Here, we report a new Ni and Ru bimetal-doped perovskite catalyst, Ba(Zr_0.1Ce_0.7Y_0.1Yb_0.1)_0.9Ni_0.05Ru_0.05O_3-δ (BZCYYbNRu), with enhanced catalytic hydrogen production activity on n-butane (C₄H₁₀), which can resist carbon coking over extended operation durations. Ru in the perovskite lattice inhibits Ni precipitation from perovskite, and the high water adsorption capacity of proton conducting perovskite improves the coking resistance of BZCYYbNRu. When BZCYYbNRu is used as a steam reforming catalyst layer on a Ni-YSZ-supported anode, the single fuel cell not only achieves a higher power density of 1113 mW cm^-2 at 700 °C under a 10 mL min^-1 C₄H₁₀ continuous feed stream at a steam to carbon (H₂O/C) ratio of 0.5 but also shows a much better operational stability for 100 h at 600 °C compared with those reported in the literature.