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The existence of defects in perovskite films is a major obstacle that prevents perovskite solar cells (PSCs) from high efficiency and long-term stability. A variety of additives have been introduced into perovskite films for reducing the number of defects. Lewis base-based additive engineering has been considered as an effective way to eliminate defects, especially the defects caused by the uncoordinated Pb2+. In this work, for the first time, a bilateral cyano molecule (succinonitrile, SN) which is a commonly used plasticizer in solid electrolyte of solid-state lithium batteries was selected as an additive to modify organic–inorganic hybrid perovskite films in PSCs. SN is featured with two cyano groups (–C≡N) distributing at both terminals of the carbon chain, providing two cross-linking points to interact with perovskites crystals via coordinating with uncoordinated Pb2+ and forming hydrogen bonds with –NH2 groups in perovskite. It was found that the addition of SN into perovskite precursor solution could effectively reduce defects, particularly inhibit the appearance of Pb0 and thus suppress trap-assisted nonradiative charge carrier recombination. As a result, the efficiency of CH3NH3PbI3(Cl) (MAPbI3(Cl))-based PSCs was improved from 18.4% to 20.3% with enhanced long-term stability at N2 and humid air atmosphere. This work provides a facile and effective strategy to enhance the PCE and stability of PSCs simultaneously, facilitating the commercialization of PSCs.

Searching for the highly active and low cost electrocatalysts with fast-charging capability for rechargeable zinc-air batteries are paramount in terms of their commercial-scale application. Here, we propose an innovative cation/anion-codoped nickel nitrides (FC-Ni3N) along with creating 3D architecture by integrating N-doped carbon nanotubes (NCNT), which is found to be an outstanding bifunctional oxygen electrocatalyst for Zn-air batteries with ultrafast charging rate (Potential =2.02V at 50 mA cm−2 with area capacity of 4 mAh cm−2) and long cycling life (700 cycles at 20 mA cm−2). Through varying the cation/anion moiety, the optimal FC-Ni3N/NCNT shows low overpotential of 260 mV at 10 mA cm−2 and Tafel slope of 46 mV dec−1, much outperforming the RuO2 benchmark with overpotential of 337 mV and Tafel slope of 91 mV dec−1. The extraordinary oxygen evolution reaction performance (corresponding to the charge process) stems from the simultaneous regulation of charge- and mass-transport kinetics in air electrodes. The proposed strategy and results may pave the way for promoting commercial application of rechargeable zinc-air batteries or other metal-air batteries.

Electrochemical water splitting is an attractive technique to produce renewable hydrogen gas. However, considerable challenges remain before the catalytic anodic oxygen evolution reaction (OER) can...

The solid-state Li-ion battery (SSB) is regarded as one of the most promising next-generation batteries due to its intrinsic safety and high energy density. Unfortunately, its development is plagued by the poor interface compatibility between the electrode and solid-state electrolyte. Herein, flame-retardant trimethyl phosphate (TMP) solvent along with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt and fuoroethylene carbonate (FEC) additive is utilized as a smart wetting agent to improve the interface compatibility between the Li-metal anode and the Li1.5Al0.5Ge1.5(PO4)(3) (LAGP) solid electrolyte. By taking advantage of such wetting agent, highly stable anodic and cathodic interfaces with improved physical contact and chemical stability are realized. As a result, the solid-state Li/LAGP/Li symmetrical cell with such wetting agent exhibits superior cycling performance over 1000 h with small polarization voltages. When adding such wetting agent to the solid-state Li/LAGP/LiFePO4 battery, we achieved a favorable initial capacity of about 140 mAh g(-1) at 0.5 C and can retain 80% of its initial capacity even after 700 cycles. Additionally, the solid-state Li-air battery with such wetting agent also shows stable cycling performance over 100 h. The strategy demonstrated here will encourage more research works on developing functional and safe wetting agents for solid-state batteries.

Due to the low material cost, simple preparation process, and no pollution to the environment, dye-sensitized solar cells (DSSCs) have become one of the important power conversion devices. The counter electrode (CE, also called cathode), an important part of DSSCs, plays a critical role in the photovoltaic performance of DSSCs. Platinum (Pt) with high electrocatalytic activity is the most commonly used CE material in DSSCs, which suffers from the problems of high price and poor stability, highlighting the importance of developing novel low-cost, active, and stable Pt-free CEs. In this work, a series of A-site deficient (La0.8Sr0.2)1–xFeO3-δ (x = 0, 0.02, 0.05, 0.1) perovskite oxides are designed to serve as CEs in DSSCs. Through investigating the influence of the A-site deficiency on the power conversion efficiency (PCE), it is found that the introduction of an appropriate deficiency in perovskite oxides is beneficial for catalytic activity of triiodide (I3–) reduction reaction (IRR) of the CE, thus improving the photovoltaic performance of DSSCs. Consequently, the (La0.8Sr0.2)0.98FeO3−δ/multiwalled carbon nanotubes (MWCNTs) CE-based device exhibits the highest PCE of 8.22%, while the Pt-based device only yields a PCE of 7.21%. The significantly enhanced efficiency of DSSCs is mainly attributed to the synergistic effect between the high oxygen vacancy concentration and the appropriate amount of Fe4+ as well as reduced particle size, which enhances the charge transfer capability and the I3– diffusion capability simultaneously. Furthermore, the decent IRR durability of (La0.8Sr0.2)0.98FeO3−δ/MWCNTs composites confers the corresponding DSSCs an excellent long-term stability. This work provides a facile way to design active and durable Pt-free perovskite oxide-based CEs in DSSCs, which may lay the foundation for the commercialization of DSSC technology.

Solid oxide fuel cells (SOFCs) based on Ni-based cermet anodes suffer from severe sulfur poisoning when operated on H2S-containing fuels (

The cycling performance of lithium-sulfur (Li-S) batteries, which is a major parameter determining the practical application of such an advanced high-energy-density battery system (1675 mA h g(-1)), is strongly affected by the properties of the cathodic sulfur hosts. As a desirable sulfur host, it should possess high surface area, good electronic conductivity, and superior physisorption and chemisorption to polysulfides. Here, by taking advantage of the magnesiothermic denitriding technology, the graphitic carbon nitride (GCN) with a tunable nitrogen content, surface area, and pore volume has been designed as a sulfur host for high-performance Li-S batteries. With a nitrogen content of similar to 6%, a surface area of 594 m(2) g(-1), and a pore volume of about 2 cm(3) g(-1), the GCN-based host can retain sulfur and allow its reversible convention within cathodic region, thereby delivering a high capacity of 852.2 mA h g(-1) at 0.5 C with a low capacity decay of 0.12% per cycle within 300 cycles. This work provides a feasible way to design nitrogen-doped carbon materials with tunable nitrogen content and enlightens the host material design for practical Li-S batteries.

A minor amount of CO2 in air usually causes a detrimental effect on oxygen activation over a solid oxide fuel cell (SOFC) cathode because insulating surface carbonate is easily formed, which inhibi...

Cost-effective electrocatalysts with high activity and long durability for the oxygen evolution reaction (OER) are key to water splitting and rechargeable metal–air batteries. Here, we report the development of a superior OER electrocatalyst with outstanding activity, favorable durability, and stable particulate morphology based on an ex situ ultra-fast cation exchange strategy that can result in fine tuning of the atom arrangement inside the oxide lattice, thus optimizing the electrocatalytic performance. O3-phase NaCo0.8Fe0.2O2 (O-NCF) is selected as the starting material, and the sodium in the oxide lattice is rapidly exchanged (several minutes) with hydronium ions (H3O+) in an acidic solution. The as-derived structure fine-tuned sample displays excellent OER performances in alkaline media with an ultra-low overpotential of only 234 mV at 10 mA cm−2 in oxide-based electrocatalysts and an ultra-small Tafel slope of 34 mV dec−1. The exchange of H3O+ with Na+ does not affect the oxidation state of cobalt and iron cations inside the oxide lattice, while protons in the inserted H3O+ promote the formation of the hydroxyl group to improve activity. As a general strategy, such cation exchange strategy can also be applied to many other layered sodium transition metal oxides.

The photocatalytic hydrogen (H2) generation relies heavily on the properties of photocatalysts, including their light absorption, charge transport, and oxygen vacancy of photocatalysts. In this work, we have successfully synthesized Ruddlesden-Popper (RP) perovskite Sr2TiO4 as photocatalysts for H2 evolution reaction (HER). Importantly, we adopted a facile and effective strategy of Ag doping and reducing pretreatment to tailor the properties of Sr2TiO4 photocatalysts. The synergistic effect of Ag doping and moderate reducing pretreatment confers Sr2TiO4 photocatalyst with improved morphological characteristics, increased specific surface area, optimized light absorption capability and band gap, suppressed charge carrier recombination as well as increased amount of surface oxygen vacancies. Benefiting from these merits, r-Ag0.05Sr1.95TiO4 with suitable amount of Ag doping and moderate reducing pretreatment displays an excellent photocatalytic performance for H2 generation, which presents average hydrogen production rates of 1695 μmol h-1 g-1 and 541 μmol h-1 g-1 under full range light irradiation (λ ≥ 250 nm) and visible light irradiation (λ ≥ 400 nm), respectively.

Perovskite oxides have been extensively investigated as catalysts for solar water splitting to generate hydrogen (H2) due to the easily tuned band gap, distinct optical/chemical properties and superior structural/compositional flexibility. Cation doping is widely used to boost the photocatalytic activity of perovskite oxides while the anion doping into the oxygen (O)-site of perovskite oxides is less investigated. Herein, we present a non-metal fluorine (F-) doping strategy to improve the photocatalytic activity of Ruddlesden-Popper Sr2TiO4 perovskites for H2 evolution reaction (HER). By optimizing the F- doping amount in Sr2TiO4-xFx, the highest H2 generation rate of 282 μmol h-1 g-1 is achieved by Sr2TiO3.97F0.03 under full-range sunlight illumination (λ ≥ 250 nm), which is 44% larger than that of Sr2TiO4 (195 μmol h-1 g-1). Such enhancement in the photocatalytic HER activity of Sr2TiO3.97F0.03 can be assigned to the increased surface oxygen vacancy amount, suppressed charge carrier recombination, more negative conduction band position as well as well-balanced band gap energy, particle size and specific surface area induced by the F- doping. Our current study presents a facile and effective strategy for the future design of highly efficient catalysts for solar water splitting.

Lithium-sulfur batteries have attracted a lot of attention in the recent years. However, the electrochemical performance of lithium-sulfur batteries is greatly affected owing to several issues. In this paper, we designed a polyaniline@spherical ordered mesoporous carbon/sulfur nanocomposite (PANI@S-OMC/S), and S-OMC/S was wrapped by PANI via in-situ polymerization. The inherently conducting nature of PANI increased conductivity of PANI@S-OMC/S electrode to improve the free transfer of electrons, and PANI shell also provided a barrier between the lithium polysulfides and electrolyte to further prevent the occurrence of the “shuttle effect”. Moreover, mesoporous pores are wonderful hosts to contain sulfur to trap the long-chain lithium polysulfides and prevent them from dissolving in electrolyte. A high initial discharge capacity of 1626 mAh/g was achieved for the PANI@S-OMC/S electrode in first cycle at 0.1 C, and the composite maintains 1338 mAh/g after 100 cycles while the coulombic efficiency still remains ∼98%.

Both the film quality and the electronic properties of halide perovskites have significant influences on the photovoltaic performance of perovskite solar cells (PSCs) because both of them are closely related to the charge carrier transportation, separation, and recombination processes in PSCs. In this work, an additive engineering strategy using antimony acetate (Sb(Ac)3 ) is employed to enhance the photovoltaic performance of methylammonium lead iodide (MAPbI3 )-based PSCs by improving the film quality and optimizing the photoelectronic properties of halide perovskites. It is found that Ac- and Sb3+ of Sb(Ac)3 play different roles and their synergistic effect contributed to the eventual excellent photovoltaic performance of MAPbI3 -based PSCs with a power conversion efficiency of above 21%. The Ac- anions act as a crystal growth controller and are more involved in the improvement of perovskite film morphology. By comparison, Sb3+ cations are more involved in the optimization of the electronic structure of perovskites to tailor the energy levels of the perovskite film. Furthermore, with the assistance of Sb(Ac)3 , MAPbI3 -based PSCs deliver much improved moisture, air, and thermal stability. This work can provide scientific insights on the additive engineering for improving the efficiency and long-term stability of MAPbI3 -based PSCs, facilitating the further development of perovskite-based optoelectronics.

Constructing porous silicon is one of the effective ways to ease the volume change (~320%) of the silicon-based anode. Thus, the design and construction of the porous structure of silicon by the particle size of Mg, the reaction temperature, ramp rate, and time of magnesiothermic reduction (MR) have achieved increasing attention. Here, a controllable self-assembled mesoporous diatomite-derived silicon nanocrystals framework (MRHDE-Si) can be adjusted directly by employing sodium chloride (NaCl) as a “liquid” interface via a MR method. As the proportion of Mg powder and NaCl increases from 1:0 to 1:10, the pore morphology level of MRHDE-Si changes from open-pore morphology to closed pore and tends to be more regular and affects the electrochemical performance of the electrode. Among as-prepared electrodes, the MRHDE-Si-5 electrode exhibits the optimal cycle performance that shows the specific capacity remains as high as 1290.9 mAh g-1 after 50 cycles at a current density of 200 mA g–1. Due to its smallest particle size of 23 nm, a suitable pore structure, pore volume (0.69 cm−3 g−1), the most feasible pore size (12.64 nm), which can provide abundant ion channels and charge transfer channels, shorten the diffusion path of Li+, enhance charge transfer capability, and effectively adapt to the stress caused by the volume expansion of Si as a buffering region. This “liquid” interface self-assembled strategy provides a simple and easy-to-operate way to design and prepare controllable porous silicon composite materials for applications in the field of new energy.

To develop a cathode with excellent oxygen reduction reaction (ORR) activity and durability at intermediate-to-low temperatures is significant to boost the advancement of solid oxide fuel cells (SOFCs), a fascinating energy conversion technology with low emissions and high efficiency. Perovskite oxides have been extensively developed as cathodes, and doping is an important strategy to alter the lattice diffusion and surface exchange properties of perovskites, to tailor catalytic performances for various redox reactions, including ORR for SOFCs. The reported BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY) is a promising cathode for SOFCs. Herein, to further improve the performance of BCFZY at reduced temperatures, we systematically investigate the partial doping of B-sites with different metal elements, including Mn, Ni, Cu and Zn at a fixed content of 5%. Among them, it is found that Ba(Co0.4Fe0.4Zr0.1Y0.1)0.95Ni0.05O3-δ (BCFZYN) exhibits the lowest polarization impedance in both oxygen ion and proton conducting fuel cells. Based on conductivity relaxation experiments and oxygen and hydrogen permeation tests, it is found that nickel doping improves oxygen mobility, surface exchange kinetics, and bulk oxygen ion and proton conductivity. Thereby, a high ORR activity on oxygen ion and proton conducting electrolytes is achieved, reaching 0.038 and 0.607 Ω cm2 at 550 °C, respectively. The cells with the BCFZYN electrode show outstanding operational stability (200 h of operation in a symmetrical cell and 1000 h of operation in a single cell). This suggests that the BCFZYN is a promising cathode of next-generation SOFCs.

Reducing the operating temperatures of solid oxide fuel cells (SOFCs) to the intermediate-temperature range (IT, 400–650 °C) can bring about several benefits including cost effectiveness, prolonged lifetime and flexible sealing. Nevertheless, the accompanying deterioration of cathodic activity for oxygen reduction reaction (ORR) introduces a large obstacle for commercial applications of IT-SOFCs. Herein, a new perovskite SrCo0.8Ti0.1Ta0.1O3-δ (SCTT) is developed by co-doping titanium and tantalum into the B-site of parent SrCoO3 oxide, which may tackle this problem. At 400–650 °C, SCTT shows high electrical conductivities (65–142 S cm−1), appropriate oxygen vacancy concentrations (0.23–0.27) and high bulk diffusion capability due to a synergy between the two dopants in SCTT. Consequently, SCTT exhibits a favorable ORR activity with an area-specific resistance of only 0.17 Ω cm2 at 500 °C on samaria-doped ceria electrolyte, and the corresponding cell generates a high peak power density (PPD) of 0.90 W cm−2 at 500 °C with negligible performance decay for 180 h. Additionally, SCTT performs well in protonic ceramic fuel cells, achieving a PPD of 0.78 W cm−2 at 650 °C and a high durability for ~176 h at 550 °C. This work provides a new promising cathode material that may accelerate the commercialization of IT-SOFC technology.

Development of efficient and green heterogeneous catalyst is a challenging goal in peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) for wastewater remediation. Perovskite-type oxides with rich physicochemical properties and flexible structure are one of the most promising categories of heterogeneous catalysts to activate PMS, while appropriate structural tuning is key to develop highly active perovskite oxides for efficient wastewater treatment. Here, we propose a simple strategy based on facile high-temperature quenching to significantly improve activity of perovskite oxide LaCoO3-δ (LCO) for PMS activation. Such quenching process improves bivalent cobalt over the surface of LCO, enhances electron transfer rate, and increases surface oxygen defects, consequently improving the decomposition rate of PMS. Specifically, compared with LCO prepared from naturally cooling at 600 °C (LCO-600-C), directly quenched LCO sample (LCO-600-Q + C) shows more than 50% improvement in catalytic activity for phenol degradation. Sulfate radical and singlet oxygen are identified as the dominating reactive oxygen species (ROS) by in-situ electron paramagnetic resonance spectroscopy and radical scavenging experiments, but a different generating rate of SO4·- over LCO-600-Q + C and LCO-600-C. Such a strategy may be suitable for the design and development of other type of materials.

Fabricating an optical microtoroid with ultra-high quality factor is an indispensable procedure both for scientific research and engineering. Here, HF/HNO 3 wet etching is specially tailored to form silicon pillars for ultra-high quality factor microtoroids instead of xenon difluoride (Xe F 2 ) or reactive ion etching (RIE) methods. This is a low-cost, easily maintained and time-saving method. The method uses a very simple etching device and is robust to temperature variations and humidity changes at room temperature(20–25 °C). Anisotropy in isotropic HF/HNO 3 etching, which may limit the quality factor, is minimized in the experiment. Quality factor dependence on silicon orientation is experimentally investigated and theoretically explained with group theory, which shows that [111] oriented silicon wafers are superior to [100] and [110] in the wet etching method. The maximum quality factor observed at 1550 nm waveband in the experiment is 1.05 × 10 8 . We believe this technique will have great influence both on laboratory and future production use.

A cobalt-free layered oxide-Sr4Fe6O13-delta is synthesized and characterized for application as a cathode of intermediate temperature solid oxide fuel cells. High temperature powder xray diffraction, oxygen temperature programmed desorption and electrochemical impedance spectroscopy are employed to evaluate the temperature-dependent crystal structure and oxygen reduction reaction (ORR) activity of Sr4Fe6O13-delta. The oxide exhibits a single phase between room temperature and 1050 degrees C with low thermal expansion coefficient. The drawback of this oxide lies on its low ORR activity which is likely due to its layered structure which favors oxygen ionic transport two-dimensionally in the ac plane along the layered oxide layer. We show here that the original ORR activity can be improved by adjusting the phase compositions through an oxygen-deficient calcination process. An area specific resistance of 0.139 Omega cm(2) at 700 degrees C is attained by calcining Sr4Fe6O13-delta at 900 degrees C with similar to 66.2 wt% of perovskite phase in the composite material. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

The development of high performance perovskite cathode for solid oxide fuel cells (SOFCs) relies upon the knowledge and understanding of the interplay between the metal oxide components, structure, redox properties and conductivity. In this work, we partially substituted Fe on SrFeO3-delta with Nb. In particular, 3 Nb-doped compositions were prepared, e.g. SrNb0.5Fe0.95O3-delta (SNF0.05), SrNb0.1Fe0.9O3-delta (SNF0.1) and SrNb0.2Fe0.8O3-delta (SNF0.2). Mossbauer spectroscopy revealed decreasing ratio of Fe4+ to Fe3+ at the higher Nb doping content which translates to the gradual decrease of the average Fe oxidation state from 3.403 (for SNF0.05) to 3.375 (for SNF0.1) and to 3.291 (for SNF0.2). Likewise, the oxygen desorption process and the thermal expansion coefficients decreased with increasing Nb content, therefore providing evidence on their correlation with the thermal reduction of Fe4+. The temperature-dependent oxygen nonstoichiometry displayed two different regimes separated by a transition temperature of 625 degrees C, below which SNF0.2 showed the highest nonstoichiometry and above which SNF0.05 provided the highest nonstoichiometry. The analogous shifting in trends was reproduced for oxygen reduction reaction (ORR) performance which signifies oxygen nonstoichiometry as the main variable affecting ORR performance. (C) 2015 Elsevier B.V. All rights reserved.

Advanced electrical energy storage technology is a game changer for a clean, sustainable, and secure energy future because efficient utilization of newable energy hinges on cost-effect and efficient energy storage. Further, the viability of many emerging technologies depends on breakthroughs in energy storage technologies, including electric vehicles (EVs) or hybrid electric vehicles (HEVs) and smart grids. Lithium-ion batteries (LIBs), a great success in the portable electronics sector, are believed also the most promising power sources for emerging technologies such as EVs and smart grids. To date, however, the existing LIBs (with LiCoOx cathode and graphite anode) are still unable to meet the strict requirements for safety, cycling stability, and rate capability. The development of advanced anode materials, which can overcome the shortcomings of graphite anode (such as formation of dendritic lithium during charge and undesirable solid electrolyte interface), is of critical importance to enhancing the cycling stability and operational safety of LIBs. Lithium titanate (Li4Ti5O12) has recently attracted considerable attentions as a potential anode material of LIBs for high power applications due to several outstanding features, including a flat charge/discharge plateaus (around 1.55 V vs. Li/Li+) because of the two-phase lithium insertion/extraction mechanism and minimum chance for the formation of SEI and dendritic lithium, dramatically enhance the potential for high rate capability and safety. In addition, there is almost no volume change during the lithium insertion and extraction processes, ensuring a high cycling stability and long operational life. However, the electronic conductivity of Li4Ti5O12 is relatively low, resulting in large polarization lose, more so at higher cycling rates, and poor rate performance. Currently, considerable research efforts have been devoted to improving the performance of Li4Ti5O12 at fast charge/discharge rates, and some important progresses have been made. In this review, we first present a general overview of the structural features, thermodynamic properties, transport properties, and the electrochemical behavior of Li4Ti5O12 under typical battery operating conditions. We then provide a comprehensive review of the recent advancements made in characterization, modification, and applications of Li4Ti5O12 electrodes to LIBs, including nanostructuring, surface coating, morphological optimization, doping, and rational design of composite electrodes. Finally, we highlight the critical challenges facing us today and future perspectives for further development of Li4Ti5O12-based electrodes. It is hoped that this review may provide some useful guidelines for rational design of better electrodes for advanced LIBs.

Steam splitting using solid oxide electrolysis cells (SOECs) is highly attractive for mass production of high-purity hydrogen, while its economic competitiveness strongly relies on the availability of low-cost, active and stable hydrogen electrodes. Here, we report an A-site cation-deficient La0.4Sr0.55Co0.2Fe0.6Nb0.2O3-δ (LSCFN55) perovskite is such a hydrogen electrode for SOEC, exhibiting a high electrolysis current density of 0.956 A/cm2 with an applied voltage of 1.3 V at 850 °C and good stability in a high humidity and hydrogen partial pressure environment. The introduction of A-site cation deficiency into the perovskite oxide lattice of LSCFN55 promotes the exsolution of partial cobalt and iron from the oxide bulk with the formation of Co2Fe alloy nanoparticles that decorate the surface of perovskite main phase, simultaneously SrO is segregated to form nanocomposites with the alloy. The outstanding electro-catalytic activity of alloy nanoparticles, the favorable water adsorption capability of SrO, the high oxygen-ion conductivity of the perovskite main phase, and the improved electronic conductivity of the material, cooperatively contribute to the superior performance of the electrode. The strong interaction between the alloy nanoparticles and the perovskite substrate effectively suppresses the sintering of the nanoparticles while the SrO phase protects the alloy nanoparticles from oxidation, both then contribute to the high operating stability of the electrode.

Constructing catalysts with a low overpotential for the oxygen evolution reaction (OER) is critical for the increased application of rechargeable Zn-air batteries. Herein, an in-situ cobalt extraction and simultaneous coordination growth strategy is adopted to develop an active and robust interface between nanostructural Co-metal-organic framework (Co-MOF) pillars and perovskite LaCoO3-δ (LC). Moreover, the multi-active cobalt sites, including Co3+ in the LC and coordinatively unsaturated cobalt sites in the Co-MOF, could promote the deprotonation of oxygen adsorption intermediates and act as catalytic active centres. Therefore, the optimal sample exhibits excellent OER activity with a low overpotential of 330 mV. Notably, the Zn-air battery with Co-MOF/LC-0.5 as the OER catalyst exhibits a low charge potential of 2.03 V and excellent cycling stability. This work illustrates efficient electrochemical catalysts based on perovskites with low overpotentials that are prepared by an in-situ growth strategy, and have great potential in rechargeable Zn-air batteries.

Dual-ion (oxygen ion and proton) conducting electrolyte BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) is one of the most commonly used electrolyte materials for proton conducting fuel cells (PCFCs). Here, we improve conducting property and performance of BZCYYb electrolyte through simply introducing B-site cation deficiency. Dual-ion conductivities for Ba(Zr0.1Ce0.7Y0.1Yb0.1)0.95O3-δ (BZCYYb-0.95) electrolyte are improved to a large extent as 2.5 times protonic conductivity (4.6 × 10−2 S cm−1 at 700 °C) and 6.3 times oxygen ionic conductivity (1.2 × 10−2 S cm−1 at 900 °C) compared to BZCYYb electrolyte. Low-temperature (1350 °C) sinterability of BZCYYb-0.95 is achieved for the higher concentration of defect compared to the original material (BZCYYb, 1500 °C). Meanwhile, a cell with the BZCYYb-0.95 electrolyte illustrates prominent power density of 794 mW cm−2 at 650 °C, superior to the cell with BZCYYb (643 mW cm−2) at the same condition. The collaborative diffusions of dual-ion via two different conducting mechanisms enhance the cell performance with BZCYYb-0.95 electrolyte. The cell voltage and power density actually have no observable performance degradation during the course of the 300-h test. Therefore, it indicates the dual-ion diffusions of BZCYYb-0.95 electrolyte as the promising future for practical application.

Oxygen anion intercalation-type supercapacitors are promising charge storage devices. In this study, by taking advantage of the capability of selective exsolution of elements from perovskite lattice, a nanoparticles-modified perovskite composite is developed as new perovskite-based electrode for supercapacitor with further improved performance that allow the energy storage via two different mechanisms, i.e., Faradaic surface redox pseudocapacitance and oxygen anion-intercalation pseudocapacitance. The derived supercapacitor shows high power density and energy density, and no surface activation process, and stable performance. Specifically, perovskite oxides with the nominal composition of Sr2CoMo1-xNixO6-δ are designed and the strategy of controlled in-situ exsolution and re-oxidation of B-sites Ni and Co element to create Co3O4 and NiO nanoparticles on the perovskite surface and extra oxygen vacancies in perovskite bulk is applied. The Co3O4 and NiO nanoparticles on surface of electrode are found to effectively improve the surface redox pseudocapacitance, while the creation of additional oxygen vacancies enhances the oxygen anion intercalation pseudocapacitance. Consequently, the electrode displays excellent charge storage capability with a stable capacity as high as ~930 F g−1 and superior rate performance. As a universal strategy, it may also be applicable for the design and synthesis of alternative high-performance electrodes with mixed energy storage mechanisms.

Perovskite oxide has been emerging as one of the efficient heterogeneous catalysts for advanced oxidation of organic contaminants in wastewater because of their structural integrity and compositional tunability. Herein, we report a new perovskite oxide, La1.15MnO3+δ with excess La, for a lowered average oxidation state of Mn cations and abundant oxygen vacancies, which can be active sites for peroxymonosulfate (PMS) activation. The La1.15MnO3+δ did exhibit improving catalytic performance as compared to LaMnO3+δ for the degradation of Rhodamine B by activating PMS. Besides, it also demonstrated high tolerance to variant water environments such as temperature, pH and impurity anions. A major non-radical activation mechanism dominated by 1O2 was further confirmed in La1.15MnO3+δ/PMS system, accompanied by a minor radical pathway. This work provides a new effective strategy to advance catalytic PMS oxidation processes by tailoring the oxidation state of B-site metals and defects of perovskite oxide through manipulating A-site cation stoichiometry.

Hydrogen (H2)-selective membrane is an enabling technology for high purity H2 production from natural gas. Here, we demonstrate the feasibility to apply BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY), a widely studied MPEC composition with high electronic conductivity as H2 permeation membrane by sputtering thin Palladium (Pd) films on its feed and permeate surfaces as a protective layer to prevent BCFZY reduction upon long-term exposure to reducing H2. Pd thin film also acts as a catalytic layer to enhance H2 dissociation in the feed surface and H association in the permeate surface. Pd-sputtered BCFZY (Pd|BCFZY|Pd) membrane displayed exceptionally high H2 flux that varies from 0.101 rise to 0.213 mL min−1 cm−2 (450 °C–650 °C) under the 10% H2-90% N2/Argon (Ar) gradient. The attainment of significant H2 permeability below 500 °C shown here indicates the possibility to lower the operating temperature for H2 permeation using MPEC materials. Pd|BCFZY|Pd membrane also demonstrated stable, high H2 flux that fluctuates more or less 0.138 mL min−1 cm−2 during the continuous operation over 225-h duration.

Although intensive efforts have been made during the past decades, development of an anode material with high specific capacity and stable cycling performance for lithium-ion batteries (LIBs) using a cost-effective preparation method still remains challenging. Herein, we report a polyaniline (PANI)-coated mechanochemically synthesized SnO2/graphene (SG) nanocomposite via in situ polymerization. PANI-coated nanocomposites are successfully prepared with different raw material mass ratios (aniline:SG, 0.15:1, 0.2:1, 0.25:1). The nanocomposite with initial aniline:SG mass ratio of 0.2:1 (20%PANI-SG) contains an optimal structure housing genuine PANI nanofibers as conductive bridges and a relatively high surface area of 158.5 m2 g−1; furthermore, it exhibits a stable cycling performance over 100 cycles at high current density (1000 mA g−1) with a specific capacity of more than twice that of the starting SG electrode at the 100th cycle. Additionally, this material achieved an outstanding cycling rate with current densities changing stepwise from 100 to 3000 mA g−1 and back, and exhibited a specific capacity of 467 mA h g−1 even at 2000 mA g−1. In terms of the electrochemical stability, rate capability and cost-effective preparation process, the PANI-SG nanocomposite is a viable anode material for next-generation high-power and high-energy LIBs.

In this study, renewable ethylene glycol (EG) was exploited as a potential fuel for solid oxide fuel cells (SOFCs) with conventional nickel yttria-stabilized zirconia (Ni–YSZ) cermet anodes for sustainable electric power generation. Carbon deposition behaviors over Ni–YSZ anodes under different carbon-containing atmospheres such as EG, glycerol, ethanol and methane were characterized through thermodynamic prediction, oxygen-temperature programmed oxidation and SEM–EDX analysis. EG was observed to be better than acetic acid and glycerol and much better than methane and ethanol in terms of carbon deposition. A calculation of the open-circuit voltages of EG-fueled SOFCs suggested that EG is a suitable fuel for SOFCs. A maximum power output of 1200 mW cm−2 at 750 °C was obtained from a cell operating on EG-steam fuel, which is only a little lower than that from a cell based on hydrogen fuel. The cell was further operated stably on an EG-steam gas mixture for 200 h with no apparent performance degradation, carbon deposition over the anode, Ni agglomeration, or change in the morphology of the anodes. The current study confirmed the practical applicability of EG as a direct fuel for SOFCs, which may have a great effect on future energy systems.

The pyrolysis of biomass was conducted using a microwave heating system operated at 2.45 GHz. Additives, such as silica carbon, activated carbon, coke produced through microwave-assisted pyrolysis, potassium carbonate, and sodium hydrate, were investigated for their effects on the sawdust pyrolysis. It was found that additives had significant effects on the yields and properties of the final products. By employing silica carbon, the gas and liquid yields were relatively low, due to the non-uniform mixing caused by big density difference between the sawdust and silica carbon particles. However, with potassium carbonate and sodium hydrate, the pyrolysis products are mainly gases, since both additives can absorb microwave strongly, making extremely high temperature inside the sawdust. The liquid products were analyzed by electrospray FT–ICR MS. Potassium carbonate can simplify the bio-oil composition and reduce compound types, which is beneficial to its further applications. The pyrolysis is highly influenced by heating rate and a first order was found for the reaction. Additives under microwave irradiation would enhance the heating rate, while they mainly act as catalysts instead of enhanced heating.

We report a carbon-air battery for power generation based on a solid-oxide fuel cell (SOFC) integrated with a ceramic CO2-permeable membrane. An anode-supported tubular SOFC functioned as a carbon fuel container as well as an electrochemical device for power generation, while a high-temperature CO2-permeable membrane composed of a CO3(2-) mixture and an O(2-) conducting phase (Sm(0.2)Ce(0.8)O(1.9)) was integrated for in situ separation of CO2 (electrochemical product) from the anode chamber, delivering high fuel-utilization efficiency. After modifying the carbon fuel with a reverse Boudouard reaction catalyst to promote the in situ gasification of carbon to CO, an attractive peak power density of 279.3 mW cm(-2) was achieved for the battery at 850 °C, and a small stack composed of two batteries can be operated continuously for 200 min. This work provides a novel type of electrochemical energy device that has a wide range of application potentials.

Cadmium selenium (CdSe) quantum dots (QDs) were synthesized using Saccharomyces cerevisiae (ATCC9763) as a biomatrix cultured with 5 mmol L−1 Na2SeO3 and 1 mmol L−1 CdCl2. Five decisive factors in the biomanufacture of CdSe QDs in S. cerevisiae were investigated and optimized, including the time point of adding Na2SeO3, the optimal concentrations of selenite and cadmium, and the incubating duration of selenite and cadmium with yeast cells respectively. By exploiting two dependent metabolic pathways in an appropriate procedure, CdSe QDs were obtained simply with controllable particle size and tunable fluorescence emission. With the help of an effective extracting method, the maximum emission peaks of different isolated QDs had been further detected, with adjustable wavelengths ranging from 506 nm (green) to 562 nm (yellow). The following in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that the biocomposed CdSe QDs had much lower cytotoxicity compared with hydrothermally synthesized thioglycolic acid (TGA)-capped CdSe and TGA capped-CdTe. By the advantages of the operational protocol, these findings exhibited the potential of an uncomplicated biosynthetic method which is capable of producing easily detectable, environment-friendly and low toxic inorganic nanoparticles with easy access of raw materials.

Robust oxygen ion conducting membranes based on doped ceria oxides can be used as oxygen permeation membranes with a short circuit to provide the required electronic conduction. Previous methods have coated both surfaces of the ion conducting electrolyte membrane with expensive noble metals as the electronic conducting phase to allow the electron shuttling required for oxygen reduction and oxidation to take place between the two membrane surfaces. During operation of the membrane, the atmosphere on the two sides of the membrane is different. The feed side is exposed to air, whereas the permeated side may be exposed to CO2 or reducing gases such as CH4 or H2. At high operating temperatures, such exposure to different gases requires the use of different materials to prepare the membranes, giving opportunities for further optimisation and the reduction of costs. In this work, a novel Ce0.9Gd0.1O2−δ membrane coated on the surface exposed to air with a cost-effective mixed conductive layer of Ba0.5Sr0.5Co0.8Fe0.2O3−δ was developed to deliver a highly stable oxygen flux for use in clean energy applications or as a membrane reactor for chemical synthesis. The membrane coated with Ba0.5Sr0.5Co0.8Fe0.2O3−δ improved the flux of oxygen compared with membranes coated with pure Ag. A triple phase boundary theory is put forward to explain the observed improvement in the oxygen flux.

Hydroxy-aluminum pillared bentonite (Al-Bent) was prepared and characterized in this work, and its dye adsorption capacity was comparatively studied in batch experiments. Results of characterization revealed that because of the intercalation of hydroxy-aluminum polyoxycations, a significant increase of interlayer basal spacing, BET surface area and total pore volume was beneficial to dyes' adsorption. The sodium bentonite had a higher adsorption affinity for Basic Fuchsin (BF) and Basic Green (BG) than Acid Turquoise Blue A (ATBA). After pillaring, the adsorption capacity of the three dyes increased and the rise of pH changed insignificantly with solution from 2 to 8. The pseudo-second-order kinetic model provided the best correlation of the experimental data (R2 > 0.99). Henry and Freundlich models both described the adsorption isotherm data well. The adsorption capacity of Al-Bent for the three dyes, especially the basic dyes BF and BG, was high over a wide range of aqueous concentrations and followed the order of BG > BF > ATBA.

In this study, pyridine was used to suppress the coke formation in solid oxide fuel cells (SOFCs) operating on liquid fuels. Pyridine can selectively occupy acidic sites of the Ni/Al 2 O 3 catalyst layer and solves the problem of dehydration of ethanol in principle, resulting in a significant reduction in the coke formation rate for operating on ethanol fuel. At 600 °C, by adding 12.5 vol.% pyridine into the ethanol fuel, the coke formation rate over the Ni/Al 2 O 3 catalyst is reduced by 64% while a cell power output comparable to that operating on hydrogen is still achieved based on total potential hydrogen available from ethanol. The effective reduction of carbon deposition on the catalyst layer thus protects the anode layer from carbon deposition by strongly suppressing coke formation, especially near the anode-electrolyte interface. Pyridine is adsorbed onto the acidic sites of the Ni/Al 2 O 3 catalyst and the adsorbed pyridine may reduce the amount of carbonium ions formed, thereby reducing coke formation. This study suggested that the addition of pyridine could suppress the coke formation in SOFCs with Ni/Al 2 O 3 catalyst layer operated on ethanol or some other similar liquid fuels.

Increasing energy demands have stimulated intense research activities on reversible electrochemical conversion and storage systems with high efficiency, low cost, and environmental benignity. It is highly challenging but desirable to develop efficient bifunctional catalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). A universal and facile method for the development of bifunctional electrocatalysts with outstanding electrocatalytic activity for both the ORR and OER in alkaline medium is reported. A mixture of Pt/C catalyst with superior ORR activity and a perovskite oxide based catalyst with outstanding OER activity was employed in appropriate ratios, and prepared by simple ultrasonic mixing. Nanosized platinum particles with a wide range of platinum to oxide mass ratios was realized easily in this way. The as-formed Pt/C-oxide composites showed better ORR activity than a single Pt/C catalyst and better OER activity than a single oxide to bring about much improved bifunctionality (DE is only approximate to 0.8 V for Pt/C-BSCF; BSCF = Ba0.5Sr0.5Co0.8Fe0.2O3-delta), due to the synergistic effect. The electronic transfer mechanism and the rate-determining step and spillover mechanism were two possible origins of such a synergistic effect. Additionally, the phenomenon was found to be universal, although the best performance could be reached at different platinum to oxide mass ratios for different oxide catalysts. This work thus provides an innovative strategy for the development of new bifunctional electrocatalysts with wide application potentials in high-energy and efficient electrochemical energy storage and conversion.

In this study, we propose and experimentally verified that methane and formic acid mixed fuel can be employed to sustain solid oxide fuel cells (SOFCs) to deliver high power outputs at intermediate temperatures and simultaneously reduce the coke formation over the anode catalyst. In this SOFC system, methane itself was one part of the fuel, but it also played as the carrier gas to deliver the formic acid to reach the anode chamber. On the other hand, the products from the thermal decomposition of formic acid helped to reduce the carbon deposition from methane cracking. In order to clarify the reaction pathways for carbon formation and elimination occurring in the anode chamber during the SOFC operation, O2-TPO and SEM analysis were carried out together with the theoretical calculation. Electrochemical tests demonstrated that stable and high power output at an intermediate temperature range was well-maintained with a peak power density of 1061 mW cm(-2) at 750 °C. With the synergic functions provided by the mixed fuel, the SOFC was running for 3 days without any sign of cell performance decay. In sharp contrast, fuelled by pure methane and tested at similar conditions, the SOFC immediately failed after running for only 30 min due to significant carbon deposition. This work opens a new way for SOFC to conquer the annoying problem of carbon deposition just by properly selecting the fuel components to realize their synergic effects.

The potential to use ethanol as a fuel places solid oxide fuel cells (SOFCs) as a sustainable technology for clean energy delivery because of the renewable features of ethanol versus hydrogen. In this work, we developed a new class of anode catalyst exemplified by Ni+BaZr0.4Ce0.4Y0.2O3 (Ni+BZCY) with a water storage capability to overcome the persistent problem of carbon deposition. Ni+BZCY performed very well in catalytic efficiency, water storage capability and coking resistance tests. A stable and high power output was well maintained with a peak power density of 750 mW cm(-2) at 750 °C. The SOFC with the new robust anode performed for seven days without any sign of performance decay, whereas SOFCs with conventional anodes failed in less than 2 h because of significant carbon deposition. Our findings indicate the potential applications of these water storage cermets as catalysts in hydrocarbon reforming and as anodes for SOFCs that operate directly on hydrocarbons.

Amorphous carbon and graphene co-modified LiFePO4 nanocomposite has been synthesized via a facile polyol process in connection with a following thermal treatment. Various characterization techniques, including XRD, Mossbauer spectra, Raman spectra, SEM, TEM, BET, O2-TPO, galvano charge-discharge, CV and EIS were applied to investigate the phase composition, carbon content, morphological structure and electrochemical performance of the synthesized samples. The effect of introducing way of carbon sources on the properties and performance of LiFePO4/C/graphene composite was paid special attention. Under optimized synthetic conditions, highly crystalized olivine-type LiFePO4 was successfully obtained with electron conductive Fe2P and FeP as the main impurity phases. SEM and TEM analyses demonstrated the graphene sheets were randomly distributed inside the sample to create an open structured LiFePO4 with respect to graphene, while the glucose-derived carbon mainly coated over LiFePO4 particles which effectively connected the graphene sheets and LiFePO4 particles to result in a more efficient charge transfer process. As a result, favorable electrochemical performance was achieved. The performance of the amorphous carbon-graphene co-modified LiFePO4 was further progressively improved upon cycling in the first 200 cycles to reach a reversible specific capacity as high as 97 mAh·g−1 at 10 C rate.

A freestanding hierarchical SnO2 nanorod/graphene composite film electrode was designed and fabricated by a general route involving electrospinning and film casting processes. With dual adaptable strategies (hierarchical nanorod structure and graphene “overcoats”), the composite film electrode exhibited enhanced cycling stability.

Doped perovskite oxides with the general formula of AA′ BB′ O have been extensively exploited as the cathode materials of solid oxide fuel cells (SOFCs), but the performance at low-to-medium temperatures still needs improvement. BaCoFeZrYO (BCFZY) has been recently reported to show promising oxygen reduction reaction (ORR) activity under SOFCs' operating conditions. Here, it is reported that the activity of BCFZY can be further boosted via introducing a slight B-site cation deficiency into the oxide lattice, and such an improvement is assigned to an increase in oxygen mobility that brings enhancement in both surface exchange and bulk diffusion kinetics. Specifically, materials with the nominal composition of Ba(CoFeZrY)O and Ba(CoFeZrY)O show significantly improved activity for ORR at reduced temperatures with the area specific resistances of 0.011 and 0.024 Ω cm at 600 °C, as a comparison of 0.042 Ω cm for the cation stoichiometric BCFZY. Excessive B-site deficiencies, however, lead to the formation of impurity phases, which cause a block for charge transfer and, consequently, a reduction in electrode performance. Introducing a B-site cation deficiency is a promising way to optimize the activity of perovskite oxides for ORR at reduced temperatures, but the degree of deficiency shall be carefully tuned.

A hybrid nano-urchin structure consisting of spherical onion-like carbon and MnO2 nanosheets is synthesized by a facile and environmentally-friendly hydrothermal method. Lithium-ion batteries incorporating the hybrid nano-urchin anode exhibit reversible lithium storage with superior specific capacity, enhanced rate capability, stable cycling performance, and nearly 100% Coulombic efficiency. These results demonstrate the effectiveness of designing hybrid nano-architectures with uniform and isotropic structure, high loading of electrochemically-active materials, and good conductivity for the dramatic improvement of lithium storage.

Seedlings of sweet sorghum were supplied with 0.1 mmol L-1, 2 mmol L-1, 5 mmol L-1 and 10 mmol L-1 nitrogen fertilizers under 0% or 0.6% NaCl conditions. Then the growth parameters of the seedlings including photosynthetic gas exchange and leaf chlorophyll a fluorescence were determined. Results showed that the seedlings grew worse under 0.6% NaCl. Furthermore, with the increase of nitrogen level, the net photosynthetic rate (Pn), transpiration rate (Tr), the maximum photochemical efficiency of PSII (PHI(Po)) , the driving force on light absorption basis (D.F), the active reaction centers per cross section (RS/CSm), trapped energy per cross section (TRo/CSm) and PQ size of photosystem (PS) II (Sm) all increased and reached the peak at 5 mmol L-1 nitrogen level. On the other hand, heat dispassion per cross section (DIo/CSm) and the close extent of PS II reaction center (Vj and M0) all decreased with nitrogen level. The results indicated that the optimum nitrogen level for sweet sorghum is about 5 mmol L-1.

Various Ni–LaxCe1−xOy composites were synthesized and their catalytic activity, catalytic stability and carbon deposition properties for steam reforming of methane were investigated. Among the catalysts, Ni–La0.1Ce0.9Oy showed the highest catalytic performance and also the best coking resistance. The Ni–LaxCe1−xOy catalysts with a higher Ni content were further sintered at 1400 °C and investigated as anodes of solid oxide fuel cells for operating on methane fuel. The Ni–La0.1Ce0.9Oy anode presented the best catalytic activity and coking resistance in the various Ni–LaxCe1−xOy catalysts with different ceria contents. In addition, the Ni–La0.1Ce0.9Oy also showed improved coking resistance over a Ni–SDC cermet anode due to its improved surface acidity. A fuel cell with a Ni–La0.1Ce0.9Oy anode and a catalyst yielded a peak power density of 850 mW cm−2 at 650 °C while operating on a CH4–H2O gas mixture, which was only slightly lower than that obtained while operating on hydrogen fuel. No obvious carbon deposition or nickel aggregation was observed on the Ni–La0.1Ce0.9Oy anode after the operation on methane. Such remarkable performances suggest that nickel and La-doped CeO2 composites are attractive anodes for direct hydrocarbon SOFCs and might also be used as catalysts for the steam reforming of hydrocarbons.

Chemically stable BaZr 0.8 Y 0.2 O 3− δ (BZY) oxide is limited to applications as an electrolyte for solid oxide fuel cells (SOFCs) because of its poor sintering behavior. This study attempts to improve the sinterability and conductivity of BZY using the partial substitution of Zr 4+ in BZY with Nd 3+ . An oxide with the nominal composition of BaZr 0.7 Nd 0.1 Y 0.2 O 3− δ (BZNY) is specifically investigated. Results from X-ray diffraction (XRD) demonstrate Nd 3+ is successfully doped into the lattice as anticipated and transmission electron microscopy (TEM) characterizations verify the morphology and crystal structure of the BZNY powder. Dilatometric measurement and scanning electron microscopy (SEM) observations provide verification that the sinterability of the oxide is effectively improved by introducing Nd 3+ . XRD and CO 2 -TPD results demonstrate that BZNY is relatively stable with respect to the CO 2 atmosphere. The total conductivity of BZNY in wet H 2 is 2.76×10 −3 S cm −1 at 600 °C. An anode-supported thin-film BZNY electrolyte (∼30 μm) cell is fabricated, and the electrolyte layer is found to be well densified after co-sintering with the anode substrate at 1450 °C for 5 h. The cell delivers a peak power density of 142 mW cm −2 at 700 °C, higher than the reported values for a similar cell with BZY electrolyte.

Nowadays, there is a doubt about the electrochemical contribution of silver current collector on the oxygen reduction reaction (ORR) over oxide electrodes in SOFCs since many reports have demonstrated that the modification of porous oxide electrodes with nano-size silver can obviously improve the electrocatalytic activity for ORR. In this study, the electrochemical contribution of silver current collector to the performance of Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3− δ (BSCF) electrode on Sm 0.2 Ce 0.8 O 1.9 (SDC) electrolyte for ORR was specifically investigated. The active layer of BSCF electrode was found to be around 25 μm by using both silver and gold current collectors. Much better performance was demonstrated by using silver current collector, both from symmetric cell and single cell tests. However, EIS of silver on SDC electrolyte demonstrated the silver alone as electrode actually had poor performance for ORR. In addition, SEM-EDX confirmed that there was no silver diffused from the current collector layer to modify the porous BSCF electrode. Interestingly, the activation energy for oxygen reduction over BSCF electrode was reduced by applying silver current collector. We then proposed a mechanism to explain the improved electrochemical performance of BSCF electrode by considering the high activity of silver for oxygen surface diffusion.

In this review, the recent progress in the application of an important category of materials, i.e. ABO3 perovskite-type compounds in the fields of energy storage and conversion, is reviewed. Four main areas, as materials for oxygen transporting membrane toward the application in oxy-fuel combustion, as key material for solid oxide fuel cells for efficient power generation from fuels, as room-temperature electrocatalysts for oxygen reduction reaction and oxygen evolution reaction, and as material for solar cells for solar energy harvest, are referred. Our past efforts in these research areas are emphasized. Some prospects about the future development in the application of perovskite materials in energy storage and conversion is proposed. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

Co-free oxides with a nominal composition of LnBaFe2O5+δ, where Ln = La, Pr, Nd, Sm, Gd, and Y, were synthesized and phase structure, oxygen content, electronic conductivity, oxygen desorption, thermal expansion, microstructure and electrochemical performance were systematically investigated. Among the series of materials tested, LaBaFe2O5+δ oxide showed the largest electronic conductivity and YBaFe2O5+δ oxide had the smallest thermal expansion coefficient (TEC) of 14.6 × 10−6 K−1 within a temperature range of 200–900 °C. All LnBaFe2O5+δ oxides typically possess the TEC values smaller than 20 × 10−6 K−1. The oxygen content, electronic conductivity and TEC values are highly dependent on the cation size of the Ln3+ dopant. The lowest electrode polarization resistance in air under open circuit voltage condition was obtained for SmBaFe2O5+δ electrode and was approximately 0.043, 0.084, 0.196, 0.506 and 1.348 Ω cm2 at 800, 750, 700, 650 and 600 °C, respectively. The SmBaFe2O5+δ oxide also demonstrated the best performance after a cathodic polarization. A cell with a SmBaFe2O5+δ cathode delivered peak power densities of 1026, 748, 462, 276 and 148 mW cm−2 at 800, 750, 700, 650 and 600 °C, respectively. The results suggest that certain LnBaFe2O5+δ oxides have sufficient electrochemical performance to be promising candidates for cathodes in intermediate-temperature solid oxide fuel cells.