Solid oxide fuel cells (SOFCs) are a promising energy conversion technology with high efficiency and environmental compatibility. Applied as anode materials, perovskite oxides govern the electrochemical performance, with an exsolution strategy for enhancing catalytic activity. In this work, Sr2Fe1.5Mo0.5O6-delta exhibits an A-site deficient surface enriched with Sr and O vacancies via the acid etching method, thereby exposing B-site cations and facilitating the nucleation process during exsolution. The optimized Fe nanoparticles distribution enhances the H2 adsorption and H2O desorption, resulting in a 25 % increase of the peak power density to 1.04 W cm-2 from 0.83 W cm- 2 at 800 degrees C. The ingenious design of surface reconstruction demonstrates significant potential in advancing perovskite-based electrocatalysts for SOFCs.

Reversible solid oxide cells (RSOCs) are capable of converting various energy resources, between electricity and chemical fuels, with high efficiency and flexibility, making them suitable for grid balancing and renewable energy consumption. However, the practical application of RSOCs is still limited by the insufficient activity and stability of the electrodes in different operating modes. Herein, a highly efficient symmetrical electrode composed of La0.3Sr0.6Ti0.1Co0.2Fe0.7O3−δ (LSTCF) nanofibers and in situ exsolved Co3Fe7 nanoparticles is developed for boosting the performance of RSOCs. The reversible phase transition, high activity and stability of the electrode have been confirmed by a combination of experimental (e.g., transmission electron microscopy and X-ray absorption fine structure) and computational studies. Electrolyte-supported RSOCs with the symmetrical electrode demonstrate excellent catalytic activity and stability, achieving a high peak power density of 0.98 W cm−2 in the fuel cell mode using H2 as the fuel (or 0.53 W cm−2 using CH4 as the fuel) and a high current density of 1.09 A cm−2 at 1.4 V in the CO2 electrolysis mode (or 1.03 A cm−2 at 1.3 V for H2O electrolysis) at 800 °C while maintaining excellent durability for over 100 h.

Solid oxide electrochemical cells exhibit high efficiency in energy storage and utilization under various operational modes. However, sluggish kinetics on the fuel side impede both the hydrogen oxidation reaction and carbon dioxide reduction reaction. A-site deficiency strategy can enhance the exsolution of highly active nanoparticles, thereby accelerating electrochemical reactions at the fuel electrode. Herein, acid treatment selectively etches surface cations of the Sr 2 Fe 1.5 Mo 0.5 O 6-δ -based fuel electrode, reconstructing an A-site deficient surface that promotes the exsolution of CoFe nanoparticles. The etched sample demonstrates a significant enhancement under both fuel cell mode and CO 2 electrolysis mode.

Solid oxide cells (SOCs) are dual-functional electrochemical devices for energy storage and conversion, offering flexibility and high efficiency. It is important to improve the catalytic activity of electrodes and to increase the redox stability of interfaces for their application. Herein, hemp rope-like nanofibers with exsolved medium-entropy-alloy (MEA) are fabricated by in situ growth of an anchored MEA/oxide interface on La0.4Sr0.4Ti0.9(Fe0.25Co0.25Cu0.25Ni0.25)0.1O3-delta (LSTFCCN) perovskite electrodes, delivering remarkably enhanced electrochemical activity under a variety of complex fuels both in fuel cell (FC) mode and electrolysis cell (EC) mode. The cell has a high peak power density of 1.01 W cm-2 in FC mode using H2 as the fuel and a high current density of 1.52 A cm-2 at 1.60 V in the CO2-H2O co-electrolysis mode at 800 degrees C. In particular, theoretical calculations reveal that the exsolved metal cluster significantly decreases the reaction energy barrier of the CO2RR and Methane Oxidation Reaction (MOR) by promoting the charge transfer between the adsorbed molecule and bulk, thereby markedly improving the electrochemical properties of the cell. We demonstrated a novel and effective approach for enhancing the catalytic performance of electrodes in SOCs, with the aim of inspiring further advancements in the development of multifunctional SOCs.

Bimetallic alloy nanoparticles (NPs) exsolved on the surface of perovskite oxides (ABO3) alter the structural and electronic properties of the primarily monometallic counterparts. These synergistic effects make the whole material present superior electrolytic and catalytic performances. The strong bonding interaction between alloy NPs and perovskite substrate enables the stability and durability of the catalysis. However, traditional thermal exsolution requires a long-time treatment at a high temperature. Researchers have been pursuing more time-saving and energy-efficient alternative routes. Herein, a low-temperature and fast pathway based on the dielectric barrier discharge (DBD) reactor is provided to in-situ exsolve alloy NPs. A favorable activity of the catalyst for photothermal catalysis is demonstrated. Additionally, we conclude that the factor that restricts metallic agglomeration is the morphology of the substrate. Even after an overtime plasma treatment, the exsolved alloy NPs are still embedded in the porous structure of perovskite oxides.

The energy system transition is widely regarded as an important strategy to achieve carbon reduction and is aligned with China's commitment to reach peak carbon emissions by 2030. Unfortunately, most modelling approaches in the existing literature do not pay sufficient attention to inter-sectoral dynamics. By using a modelcoupling approach, this paper aims to study inter-sectoral energy consumption flows from 2000 to 2021 and to explore energy system transition pathways at the national and city levels. The results show that historically heavy industries have consistently maintained a high share of energy consumption and emissions accounting for 49.9 % and 60.7 % respectively by 2021, mainly caused by direct energy-resource inputs rather than postprocessing inputs. In the scenario analyses, compared to the baseline scenario, the national EES scenario can reduce energy consumption by 6.7 % and emissions by 24.6 % in 2030, while the EES_CCS scenario can further reduce emissions by 48.4%. Furthermore, the energy consumption and CO2 emissions across cities are influenced by the industrial structure, the degree of electrification, and the amount of new energy installed.

Bimetallic alloy nanoparticles (NPs) exsolved on the surface of perovskite oxides (ABO 3 ) alter the structural and electronic properties of the primarily monometallic counterparts. These synergistic effects make the whole material present superior electrolytic and catalytic performances. The strong bonding interaction between alloy NPs and perovskite substrate enables the stability and durability of the catalysis. However, traditional thermal exsolution requires a long-time treatment at a high temperature. Researchers have been pursuing more time-saving and energy-efficient alternative routes. Herein, a low-temperature and fast pathway based on the dielectric barrier discharge (DBD) reactor is provided to in-situ exsolve alloy NPs. A favorable activity of the catalyst for CO oxidation is demonstrated. Additionally, we conclude that the factor restricts metallic agglomeration is the morphology of the substrate. Even after an overtime plasma treatment, the exsolved alloy NPs are still embedded in the porous structure of perovskite oxides.

Perovskite oxides are promising electrodes for protonic ceramic fuel cells (PCFCs) due to their good electrochemical performance and stability. However, the lower operating tem-perature results in a large polarization resistance and sluggish oxygen reduction reaction (ORR) in cathodes. Herein, Ruddlesden-Popper (R-P) type perovskite Sr3Fe2-xZnxO7-$ (SFZx, x = 0, 0.1, 0.5) were successfully synthesized and the partial replacement of Fe by Zn in SFZx demonstrates a superior ORR activity. At 750 degrees C, the polarization resistance of SFZ05 is 0.072 U cm -2, which is 47% lower than that of the undoped Sr3Fe2O7-$ (SFO), and the peak power density of the single-cell with an SFZ05 cathode reaches 523.56 mW cm -2. The distribution of relaxation time (DRT) results manifest that the rate-limiting steps of ORR are charge transfer and ionic migration processes. Furthermore, SFZ05 also presented better CO2 tolerance. These results show that SFZ05 is a promising cathode candidate with high activity and stability for PCFCs.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

AbstractSolid oxide cells (SOCs) are promising energy‐conversion devices due to their high efficiency under flexible operational modes. Yet, the sluggish kinetics of fuel electrodes remain a major obstacle to their practical applications. Since the electrochemically active region only extends a few micrometers, manipulating surface architecture is vital to endow highly efficient and stable fuel electrodes for SOCs. Herein, a simple selective etching method of nanosurface reconstruction is reported to achieve catalytically optimized hierarchical morphology for boosting the SOCs under different operational modes simultaneously. The selective etching can create many corrosion pits and exposure of more B‐site active atoms in Sr2Co0.4Fe1.2Mo0.4O6‐δ fuel electrode, as well as promote the exsolution of CoFe alloy nanoparticles. An outstanding electrochemical performance of the fabricated cell with the power density increased by 1.47 times to 1.31 W cm−2 at fuel cell mode is demonstrated, while the current density reaches 1.85 A cm−2 under 1.6 V at CO2 electrolysis mode (800 °C). This novel selective etching method in perovskite oxides provides an appealing strategy to fabricate hierarchical electrocatalysts for highly efficient and stable SOCs with broad implications for clean energy systems and CO2 utilization.

The traditional oxygen electrode in solid oxide electrolysis cells (SOECs), (La,Sr)(Co,Fe)O-3 (LSCF), suffers from high cost, evaporation at high temperatures, and societal aspects of the use of Co. In this work, a Co-free B-site multielement (so-called high-entropy) perovskite oxide, La0.6Sr0.4Cu0.2Fe0.2Ti0.2Mn0.2Ni0.2O3-delta (LSCuFTMN), has been synthesized and successfully applied as a novel oxygen electrode. X-ray photoelectron spectroscopy (XPS) data indicate that the multiple transition elements in the B-site exist in various valence states, leading to a spatially variable electron structure. Electrochemical measurements of LSCuFTMN suggest that the material exhibits extraordinary catalytic activity and stability under the studied working atmospheres and a decrease in polarization resistance by 24% compared to LSCF. By distribution of relaxation time (DRT) analysis, LSCuFTMN possesses better mass and charge transfer performance than traditional LSCF. An SOEC with LSCuFTMN as the oxygen electrode has been assembled and tested, and a current density of 1.2 A cm(-2) is obtained at 2.0 V and 800 degrees C in electrolysis of pure CO2, higher by nearly 50% compared to LSCF. The faradaic efficiency is over 95%. No clear recession is observed in the long term stability test. It is evident that multication - so-called high-entropy - oxides could be promising materials for improving the working performance of SOECs.

Efficient catalysts for the oxygen evolution reaction (OER) are critical to the progress of electrochemical devices for clean energy conversion and storage. Although heterogeneous electrocatalysts have superior activity, it is a great challenge to elucidate electron transfer at surface catalytic sites and intrinsic mechanisms. Herein, we demonstrate a new type of heterostructure electrocatalyst in which Sr0.9Ce0.05Fe0.95Ru0.05O3 fibers are hybridized with in situ grown RuO2 nanoparticles (SCFR-RuO2). We investigate its unique structure, electron transfer mechanisms related to the highly OER activity by combining experimental and theoretical calculations. Remarkably, SCFR-RuO2 shows an optimized OER overpotential of 295 mV at 10 mA cm-2. The promoted electron transfer and OER kinetics are ascribed to the coupling of electronic effects at the SCFR-RuO2 heterostructure. A strong triangular relationship among overpotential-Tafel slope-work function is proposed to be a potential descriptor of OER activity in SCFR-RuO2. These insights provide guidelines for tuning the OER performance via modified work functions in perovskite electrocatalysts.

Perovskite oxides have attracted intensive attention for their good electrochemical performance and stability as electrodes for protonic ceramic fuel cells (PCFCs). However, operating under high temperatures and various atmospheres results in a large polarization resistance and sluggish oxygen reduction reaction (ORR) in cathodes. Here, Zn was successfully doped into Sr 3 Fe 2 O 7-δ (SFO) Ruddlesden-Popper (RP) perovskite cathode and the Sr 3 Fe 1.5 Zn 0.5 O 7-δ (SFZ05) shows a superior ORR activity. The polarization resistance of SFZ05 is 0.072 Ω·cm -2 , which is 47% lower than that of the undoped SFO, and the maximum peak power density of the single-cell of NiO-BaZr 0.1 Ce 0.7 Y 0.2 O 3-δ (BZCY)|BZCY|SFZ05 reaches 523.56 mW·cm -2 at 750℃, increased by 22% than SFO. The improvement is attributed to the formation of oxygen vacancies and the increase of proton conductivity. These results display that SFZ05 is a promising candidate for a highly active and stable cathode for PCFCs.

Reversible solid oxide cells (RSOCs) as new energy converting devices with superior conversion efficiency can operate in both fuel cell (FC) mode and electrolysis cell (EC) mode. However, the main challenges for fuel electrode materials are poor electrochemical performance and limited durability due to the sluggish hydrogen catalysis kinetics. Here, we demonstrate an advanced fiber-structured La x Sr x Ti 0.9 Ni 0.1 O 3-δ (LSTNx) architecture with a series of A-site deficiency (x=0.5, 0.45, and 0.4), which can be applied to reversible solid cells as a promising candidate of fuel electrode materials. LSTNx fibers decorated with Ni nanoparticles (NPs) were fabricated via electrospinning technique and in-situ exsolution method. A-site deficiency played a critical role in Ni exsolution and the morphology of LSTNx nanofibers. La 0.4 Sr 0.4 Ti 0.9 Ni 0.1 O 3-δ fibers with moderate A-site deficiency displayed homogeneous Ni NPs on the surface and excellent stability at 800℃ in pure H 2 . A single cell with LSTN0.4 fuel electrode (~40 μm) | GDC barrier layer (~0.5 μm) | SSZ electrolyte (~250 μm) | GDC barrier layer (~0.5 μm) | composite LSCF-GDC air electrode (~40 μm) exhibits maximum power density of 547.44 mW·cm -2 at 800℃ in wet H 2 and the current density of -1.351 A·cm -2 under the potential of 1.5 V in 50% H 2 O/H 2 atmosphere. The 5-cyclic long-term reversible tests of FC and EC modes were carried out under the potential of 0.5/1.5 V for 60 h, respectively. The current density degradation was approximately 0.67% in EC mode and 2.73% in FC mode after 5-cyclic reversible tests in LSTN0.4 single cells, suggesting a reliable fiber-structured architecture for RSOCs. Figure 1

Solid oxide electrolysis cell(SOEC) could be a potential technology to afford chemical storage of renewable electricity by converting water and carbon dioxide.In this work,we present the Ni-doped layered perovskite oxides,(La 4 Sr n-4 ) 0.9 Ti 0.9n Ni 0.1n O 3n+2 with n=5,8,and 12(LSTNn) for application as catalysts of CO 2 electrolysis with the exsolution of Ni nanoparticles through a simple in-situ growth method.It is found that the density,size,and distribution of exsolved Ni nanoparticles are determined by the number of n in LSTNn due to the different stack structures of TiO 6 octahedra along the c axis.The Ni doping in LSTNn significantly improved the electrochemical activity by increasing oxygen vacancies,and the Ni metallic nanoparticles afford much more active sites.The results show that LSTNn cathodes can successfully be manipulated the activity by controlling both the n number and Ni exsolution.Among these LSTNn(n=5,8,and 12),LSTN8 renders a higher activity for electrolysis of CO 2 with a current density of 1.50A cm -2 @2.0 V at 800℃ It is clear from these results that the number of n in(La 4 Sr n-4 ) 0.9 Ti 0.9n Ni 0.1n O 3n+2 with Ni-doping is a key factor in controlling the electrochemical performance and catalytic activity in SOEC.

The development of high-performance cathodes with low polarization resistance and good tolerance to CO2 are important issues for solid oxide fuel cells (SOFC). In this work, we synthesized LaSrCoO4-Ce0.9Mn0.1O2 (LSCO4CMO) composite cathode materials by the citric acid-nitrate method. The composite cathode sintered at 950 degrees C for 4 h shows large porous morphology and superior electrochemical activity of oxygen reduction reaction (ORR). Electrochemical properties analysis suggests that LSCO4-35 wt% CMO (L-35C) exhibits the lowest polarization resistance (R-p) at 800 degrees C and the value of R-p is 0.14 Omega cm(2) which is far lower than that of pure LSCO4 (0.77 Omega cm(2)). It is found that the LSCO4-CMO has unique microstructure and more active sites for ORR. Moreover, the doping of CMO offers more oxygen ions transport channels as the concentration of oxygen vacancies increases. The study of the effect of oxygen partial pressure on Rp reveals that as the temperature rises, the rate of dissociation of oxygen molecules is significantly accelerated, indicating that the charge transfer of oxygen atoms becomes the main rate-limiting step. A high oxygen reduction catalytic activity and excellent CO2 tolerance were demonstrated in L-35C by O-2-TPD and CO2-TPD tests, making LSCO4-CMO a potential candidate for SOFC cathode.

In-situ exsolution technique, as an efficient and controllable strategy of surface modification, has been extensively applied in reversible solid oxide cells (RSOCs). Here, we demonstrate LaxSrxTi0.9Ni0.1O3-delta fiber decorated by exsolved Ni nanoparticles and highlight the impacts of A-site deficiency on Ni exsolution and electrochemical performance of RSOCs. The La0.4Sr0.4Ti0.9Ni0.1O3 (A/B = 0.8) fibrous fuel electrode decorated by Ni nano-particles with moderate Ni exsolution displays optimum electrochemical performance at 800 degrees C, achieving similar to 540 mW cm(-2) in SOFC mode and-0.742/0.385 A cm(-2) under 1.3/0.7 V in RSOC mode. In contrast, high A-site deficiency (A/B < 0.8) allows heterogeneous phases (NiTiO3) and excessive Ni exsolution along with alterations of fibrous morphology, leading to slow gas diffusion, sluggish catalysis, and Ni agglomeration. The distribution of relaxation time (DRT) results show that the rate-limiting steps in symmetrical cells are gas diffusion, hydrogen adsorption, and dissociation, accounting for over 89% of the total RP. Ni-equilibrium model based on X-ray Rietveld refinement calculates the degree of exsolution with various A-site deficiency, revealing NiTiO3 is the key factor of excessive exsolution. Our work of high A-site deficiency exemplified here may serve in the design and nanoengineering of fibrous ABO(3) perovskite oxides for RSOCs.

Solid oxide cell (SOC) is the energy conversion device with a series of advantages such as high efficiency, environmental friendliness and durability, making it a promising way to deal with environmental pollution and energy crisis appearing with the development of human society. Perovskite oxides with hetero-phases which were prepared by in-situ exsolution are widely used as fuel electrode in SOC. In this work, Ni-doped perovskites Ruddlesden–Popper oxides, (La, Sr)nTinO3n-2 with n = 5, 8, and 12 (LSTNn), were synthesized to design novel exsolution materials as solid oxide fuel cell anodes and for electrochemical catalysis applications. Compared with pure LSTNn without Ni, a small A-site deficiency (10%) promoted the exsolution of Ni from the perovskite oxides of Ni-doped LSTNn. It is found that the morphology as well as electrochemical activity of LSTNn anodes can be successfully manipulated by the exsolution of Ni. Since more Ni nanoparticles are exsolved from the parent oxides, LSTN8 displays better electrochemical performance by providing more active sides during the hydrogen oxidation reaction and significantly lowering electrode polarization resistance. DRT analysis is conducted to study substeps of the whole electrode reaction, finding that in-situ precipitation improves rate-limiting steps much. The CO2 reduction reaction performance of LSTN materials is also studied, finding that in-situ grown nanoparticles on surface of LSTN significantly increases the density of surface active sites and three phase boundaries (TPBs), which are beneficial for CO2 adsorption and subsequent conversion. It is clear from these results that varying Ni-doping in Ruddlesden–Popper oxides is a key factor in controlling the electrochemical performance and catalytic activity for hydrogen oxidation reaction in solid oxide fuel cells.

A hybrid metal-semiconductor can be utilized as an attractive photocatalyst which demonstrates unique synergistic properties stemming from the materials combination. One of the essential advancements is precisely controllable for each geometrical factor in metal and its semiconductive support. Herein, we synthesized Sr0.9Ti0.9Ru0.1O3-δ (STRO) fibers by the electrospinning method and tailored the morphology by in-situ exsolved Ru nanoparticles (NPs). Thus, a metal-semiconductor heterostructure is formed. The hierarchical Ru-STRO catalyst manifested a remarkable enhancement of solar-assisted photocatalytic activity with a 5-fold increase in hydrogen evolution rate, attributed to enhanced charge separation, reaction sites, and light absorption. Theoretical simulations and Kelvin probe force microscopy (KPFM) explained the reaction pathways of photogenerated carriers and how their partitioning and transportation are tuned by Ru NPs. Our work provides a novel method to easily fabricate metal-semiconductor heterostructure via an in-situ growth method for the development of high-performance photocatalysts.

可逆固体氧化物电池(RSOC)因具备高效可逆的发电和电解产氢性能,被认为是一种具有良好发展前景的能源转化设备.然而,缺乏高活性和稳定性的电极材料是限制RSOC广泛应用的主要因素之一.传统的燃料电极一般采用浸镍的氧化钇稳定氧化锆(Ni?YSZ)材料,而氧电极则以钙钛矿型的氧化物居多.目前使用的燃料电极和氧电极的电化学性能都存在一定的不足.近期,诸多研究报道SrTiO3基钙钛矿材料具有良好的稳定性和电化学性能,有望成为RSOC电极的热门候选材料.近年来,虽然对RSOC电极的研究较多,但是缺乏对该类材料系统的归纳和总结.因此,本文综述了SrTiO3基钙钛矿材料在RSOC电极方面的应用进展.首先,系统分析了SrTiO3基钙钛矿材料在RSOC燃料电极和氧电极的研究现状,介绍了目前常用的SrTiO3改性的手段和策略,如掺杂其他元素、构建非ABO3化学计量比氧化物、构建复合材料以及利用原位纳米颗粒出溶技术等;其次,探讨了SrTiO3基钙钛矿材料应用于对称结构RSOC电极的可行性;最后,结合构建未来新一代RSOC高性能能源互联器件,展望了SrTiO3基钙钛矿材料在RSOC中的应用前景,并提出了亟需解决的问题.

Solid oxide fuel cells (SOFCs) are ideal devices for converting energy since they combine fuel flexibility with high efficiency. Understanding oxygen reduction reaction (ORR) is vital to developing and designing novel cathode materials for low-temperature operation in SOFCs. In this work, the first-principle theory has been applied to explore the interaction of oxygen molecules on YFe0.5Co0.5O3 (YFC) which could be used as a novel perovskite cathode. The oxygen species are investigated by the analyses of electronic structure and differential charge density. It is found that a strong hybridization between transition metals (Co/Fe) and O when oxygen molecular adsorbed on YFC surface. Cobalt dopant is demonstrated to play a critical role in decreasing the reaction barrier by comparing the minimum energy paths (MEPs) of ORR. Furthermore, the increase in the O 2p band center also proves that YFC with the partial substitution of Fe by Co could improve the catalytic activity of ORR. The minimum energy paths (MEPs) of the ORR on the surfaces of YFC (1 1 0).