Search

Due to the high energy density, mature production technology, ease of storage and transportation, and the no carbon/sulfur nature of ammonia fuel, direct-ammonia solid oxide fuel cells (DA-SOFCs) have received rapidly increasing attention, showing distinct advantages over H2-fueled SOFCs and low-temperature fuel cells. However, DA-SOFCs with conventional Ni-based cermet anodes still suffer from several drawbacks, including serious sintering and inferior activity for ammonia decomposition, strongly limiting the large-scale applications. To tackle the above-mentioned issues, exsolved NiCo nanoparticles decorated double perovskite oxides are fabricated and employed as high-performance anodes for DA-SOFCs in this work. By optimizing the Ni doping amount in Sr2CoMo1−xNixO6−δ (x = 0.1, 0.2 and 0.3), the reduced Sr2CoMo0.8Ni0.2O6−δ (r-SCMN2) anode exhibits superb catalytic activity for ammonia cracking reaction and high anti-sintering capability. More specifically, the electrolyte-supported single cell with r-SCMN2 nanocomposite anode delivers superior power outputs and operational durability in ammonia fuel as compared with other r-SCMN anodes owing to the significantly promoted nanoparticle exsolution and stronger interaction between alloy nanoparticles and the support. In summary, this study presents an effective strategy for the design of efficient and stable nanocomposite anodes for DA-SOFCs.

Polysaccharides and polyphenols coexist in many plant-based food products. Polyphenol–polysaccharide interactions may affect the physicochemical, functional, and physiological properties, such as digestibility, bioavailability, and stability, of plant-based foods. In this review, the interactions (physically or covalently linked) between the selected polysaccharides and polyphenols are summarized. The preparation and structural characterization of the polyphenol–polysaccharide conjugates, their structural–interaction relationships, and the effects of the interactions on functional and physiological properties of the polyphenol and polysaccharide molecules are reviewed. Moreover, potential applications of polyphenol–polysaccharide conjugates are discussed. This review aids in a comprehensive understanding of the synthetic strategy, beneficial bioactivity, and potential application of polyphenol–polysaccharide complexes.

Protonic ceramic fuel cells (PCFCs), as an efficient energy storage and conversion device, have great potential to solve the serious problems of energy shortage and environmental pollution. Improving the proton conductivity of the promising cathode materials is an effective solution to promote the widespread application of PCFCs at low temperatures (450-650 °C). Herein, considering the high oxygen reduction reaction (ORR) activity of BaCoO

In this study, the oxygen reduction activity of PrBaCo2O5+δ (PBC) double perovskite is remarkably enhanced by rationally tuning the calcination temperatures of the cathode precursor for solid oxide fuel cells (SOFCs). Effects of the calcination temperatures on the phase structure, microstructure, surface area and oxygen reduction reaction (ORR) activity of PBC cathode is systematically investigated. The cathode with optimized calcination temperature (900 °C, PBC-900) shows excellent activity and stability for ORR at 600 °C in terms of area specific resistances (ASRs). A distinctive low ASR of 0.068 Ω cm2 is obtained at 600 °C for PBC-900, which is 92.6%, 34.6% and 15.0% lower than PBC-800, PBC-1000 and PBC-1100, respectively. After operating for 250 h in air at 600 °C, the ASR value of PBC-900 is not significantly reduced. Furthermore, a single cell with PBC-900 cathode delivers attractive peak power density of 1.60 W cm−2 at 600 °C. The present study suggests that the ORR activity of PBC cathode can be greatly boosted by rationally tailoring the calcination temperatures, which may bring new avenue for the design of highly active cathodes for SOFCs.

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

Solid oxide fuel cells (SOFCs) as one of the clean electrochemical energy conversion devices have acquired increasing attention recently due to the high efficiency, low emission, and excellent fuel...

The requirement for a sustainable and renewable energy has inspired substantial interests in designing and developing earth-abundant and high-effectiveness electrocatalysts/electrodes for fuel cells and metal-air batteries, in which oxygen reduction reaction (ORR) plays a crucial role. Perovskite oxides have acquired rapid attention as ORR electrocatalysts to replace noble-metal-based catalysts owing to their intrinsic electrocatalytic activity, compositional and structural flexibility. Herein, we report a new Sc and P co-doped perovskite oxide (La0.8Sr0.2Mn0.95Sc0.025P0.025O3-δ, LSMSP) as an active and robust electrocatalyst for the ORR in an alkaline solution. LSMSP electrocatalyst shows superior ORR activity and stability than those of pristine La0.8Sr0.2MnO3-δ (LSM), Sc-doped LSM and P-doped LSM due to the optimized average valence of Mn ions, the large surface area, the smaller particle size and the synergetic effect introduced by the co-doping. Moreover, compared to the benchmark Pt/C electrocatalyst, LSMSP electrocatalyst displays comparable ORR activity and superior durability. These above results suggest that the co-doping strategy of Sc and P into perovskites is a useful method to design high-performance electrocatalysts for the ORR, which can be used in other electrocatalysis-based applications.

Triiodide/iodide (I3-/I-) redox couple-mediated solar cells, batteries, and electrochromic devices require highly efficient and stable electrocatalysts for I3- reduction reaction (IRR) to overcome performance limitations, whereas the widely used platinum (Pt) cathode for IRR has limitations of high price and unfavorable durability. In this work, we present a halogen element (chlorine) doping strategy to design low-cost perovskite-type electrocatalysts with enhanced IRR activity and stability. The dye-sensitized solar cell (DSSC) assembled by the LaFeO2.965-δCl0.035 cathode delivers an attractive power conversion efficiency (PCE) of 11.4% with a remarkable PCE enhancement factor of 23% compared with Pt, which is higher than most of the reported non-Pt DSSC cathodes. Attractively, LaFeO2.965-δCl0.035 displays superior IRR activity/stability and structural stability in the I3-/I--based electrolyte compared to pristine LaFeO3 because chlorine doping facilitates the creation of oxygen vacancies (active sites) and enhances surface acidity simultaneously. This study provides a new way for designing outstanding IRR electrocatalysts, which could be applied to many redox couple-mediated photo/electrochemical devices.

Research on the efficient synthesis and application of nanostructured perovskite oxides is attracting intensive attention nowadays. Herein, a silver (Ag) nanoparticle decorated A-site deficient perovskite is prepared using a facile exsolution method and used as a cathode in dye-sensitized solar cells (DSSCs). The Ag nanoparticle modified (La0.8Sr0.2)0.95MnO3−δ composite (e-LSAM) prepared by the exsolution method displays exceptional activity for the electrocatalytic triiodide (I3−) reduction reaction (IRR) in DSSCs, which is much superior to that of the Ag/perovskite hybrids synthesized by physical mixing and impregnation methods due to the strong interfacial interaction and small Ag particle size. DSSC with this newly developed heteroelectrocatalyst shows a high photovoltaic efficiency of 12.4%, surpassing that of the expensive platinum (Pt)-based control cell (9.93%) with an enhancement factor of 25%, which is among the highest performances of Pt-free cathodes reported to date. Moreover, this new composite cathode shows a much superior IRR durability to Pt, indicating its great potential for replacing Pt. This study paves the way for the rational design of active and durable perovskite electrocatalysts for various energy conversion and storage systems.

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

Anode-supported protonic ceramic fuel cells (PCFCs) are highly promising and efficient energy conversion systems. However, several challenges need to be overcome before these systems are used more widely, including the poor sintering of recently developed proton-conducting oxides and the decreased proton conductivity due to detrimental reactions between the nickel from anode and the electrolyte occurring during high-temperature co-sintering. Herein, a Ni doping strategy to increase the electrolyte sintering, suppress the detrimental phase reactions, and generate stable Ni nanoparticles for enhanced performance is proposed. A nickel-doped perovskite oxide is developed with the nominal composition of Ba(Zr

One challenge for the commercial development of solid oxide fuel cells as efficient energy-conversion devices is thermo-mechanical instability. Large internal-strain gradients caused by the mismatch in thermal expansion behaviour between different fuel cell components are the main cause of this instability, which can lead to cell degradation, delamination or fracture1-4. Here we demonstrate an approach to realizing full thermo-mechanical compatibility between the cathode and other cell components by introducing a thermal-expansion offset. We use reactive sintering to combine a cobalt-based perovskite with high electrochemical activity and large thermal-expansion coefficient with a negative-thermal-expansion material, thus forming a composite electrode with a thermal-expansion behaviour that is well matched to that of the electrolyte. A new interphase is formed because of the limited reaction between the two materials in the composite during the calcination process, which also creates A-site deficiencies in the perovskite. As a result, the composite shows both high activity and excellent stability. The introduction of reactive negative-thermal-expansion components may provide a general strategy for the development of fully compatible and highly active electrodes for solid oxide fuel cells.

Direct ammonia solid oxide fuel cell (DA-SOFC) is superior to low-temperature direct ammonia fuel cell using anion exchange membrane because of much improved anode reaction kinetics at elevated temperature. However, significant performance degradation due to severe sintering of conventional nickel cermet anode under operating conditions is a big challenge for realizing its practical use. Herein, a high-performance anode based on LaSrTiO (LST) perovskite substrate with its surface decorated with in situ exsolved and strongly coupled NiCo alloy nanoparticles (NPs) is designed and fabricated for DA-SOFCs, exhibiting superior catalytic activity for NH decomposition reaction due to balanced NH adsorption and N desorption processes. An electrolyte-supported single cell with infiltrated NiCo/LST on SmCeO scaffold anode delivers a maximum power density of 361 mW cm at 800 °C in NH fuel, superior to similar SOFCs with Ni or Co NP-decorated LST based anodes (161 and 98 mW cm). Furthermore, the SOFC with this newly developed anode displays favorable operational stability without obvious performance degradation at 700 °C for a test period of ≈120 h, attributed to its high antisintering capability. This study provides some strategies to develop highly active, stable, and antisintering perovskite-based nanocomposite for DA-SOFCs, facilitating the practical use of this technology.

Photoelectrochemical (PEC) water splitting is an attractive strategy for the large-scale production of renewable hydrogen from water. Developing cost-effective, active and stable semiconducting photoelectrodes is extremely important for achieving PEC water splitting with high solar-to-hydrogen efficiency. Perovskite oxides as a large family of semiconducting metal oxides are extensively investigated as electrodes in PEC water splitting owing to their abundance, high (photo)electrochemical stability, compositional and structural flexibility allowing the achievement of high electrocatalytic activity, superior sunlight absorption capability and precise control and tuning of band gaps and band edges. In this review, the research progress in the design, development, and application of perovskite oxides in PEC water splitting is summarized, with a special emphasis placed on understanding the relationship between the composition/structure and (photo)electrochemical activity.

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.

An ideal solid oxide fuel cell (SOFC) cathode should meet multiple requirements, i.e., high activity for oxygen reduction reaction (ORR), good conductivity, favorable stability, and sound thermo-mechanical/chemical compatibility with electrolyte, while it is very challenging to achieve all these requirements based on a single-phase material. Herein, a cost-effective multi-phase nanocomposite, facilely synthesized through smart self-assembly at high temperature, is developed as a near-ideal cathode of intermediate-temperature SOFCs, showing high ORR activity (an area-specific resistance of ≈0.028 Ω cm2 and a power output of 1208 mW cm-2 at 650 °C), affordable conductivity (21.5 S cm-1 at 650 °C), favorable stability (560 h operation in single cell), excellent chemical compatibility with Sm0.2 Ce0.8 O1.9 electrolyte, and reduced thermal expansion coefficient (≈16.8 × 10-6 K-1 ). Such a nanocomposite (Sr0.9 Ce0.1 Fe0.8 Ni0.2 O3-δ ) is composed of a single perovskite main phase (77.2 wt%), a Ruddlesden-Popper (RP) second phase (13.3 wt%), and surface-decorated NiO (5.8 wt%) and CeO2 (3.7 wt%) minor phases. The RP phase promotes the oxygen bulk diffusion while NiO and CeO2 nanoparticles facilitate the oxygen surface process and O2- migration from the surface to the main phase, respectively. The strong interaction between four phases in nanodomain creates a synergistic effect, leading to the superior ORR activity.

A favorable micro-nanostructure is crucial for obtaining superior properties. However, the synthetic techniques for synthesizing the complex morphology still remain a challenge. In this work, we synthesized core–shell-structured submicrometer-sized mesoporous TiO2 microspheres (MTMs) constructed with mesoporous TiO2 polyhedrons through a novel anisotropic etching route. The outer shell of the obtained TiO2 microsphere is constructed by a mesoporous TiO2 single-crystal nanopolyhedron with exposed (101) facets. Hydrogen peroxide was used as the bubble generator, which simultaneously acted as gas templates for the formation of TiO2 microspheres. Fluorine ions facilitate the formation of anatase (001) facets at the beginning of the reaction. The anisotropic etching accrued along the [101] direction with an increase in fluorine ions, leaving mesoporous structures and highly exposed (101) facets. Dye-sensitized solar cells (DSSCs), using the as-prepared product as a light-scatting layer, showed a 29.4% increase...

State-of-the-art dye-sensitized solar cells (DSSCs) usually use the noble and scarce platinum (Pt) cathode, which strongly limits the practical applications of DSSCs. Accordingly, low-cost, highly active, and stable alternatives to Pt are highly desired. Herein, an intrinsically conductive perovskite oxide is reported as a new cathode for DSSCs using a simple nonmetal element doping strategy. The phosphorus-doped perovskite oxide (SrCoPO [SCP]) shows superior activity/durability for the triiodide (I ) reduction reaction (IRR) and structural stability relative to the parent compound (SrCoO [SC]) due to the greatly enhanced electrical conductivity and the stabilization of the perovskite structure. The internal conducting pathways are demonstrated to be very important to obtain high IRR activity of the perovskite cathode, even when the cathode is incorporated with conductive multiwalled carbon nanotubes (MWCNTs). The DSSC with the N719 dye and SCP/MWCNTs cathode displays a superior power conversion efficiency (PCE) of 10.1% to those with Pt (8.11%) and SC/MWCNTs (6.80%) cathodes. In addition, the DSSC with the C101 dye and SCP/MWCNTs cathode shows an attractive PCE of 12.2% with an enhancement of 23%, as compared with the Pt cathode, suggesting that the SCP/MWCNTs composite can be one of the best substitutions to the Pt cathode, which can benefit the future industrialization of DSSCs.

The development of cost-effective and high-performance electrocatalysts for the hydrogen evolution reaction (HER) is one critical step toward successful transition into a sustainable green energy era. Different from previous design strategies based on single parameter, here the necessary and sufficient conditions are proposed to develop bulk non-noble metal oxides which are generally considered inactive toward HER in alkaline solutions: i) multiple active sites for different reaction intermediates and ii) a short reaction path created by ordered distribution and appropriate numbers of these active sites. Computational studies predict that a synergistic interplay between the ordered oxygen vacancies (at pyramidal high-spin Co sites) and the O 2p ligand holes (OLH; at metallic octahedral intermediate-spin Co sites) in RBaCo O (δ = 1/4; R = lanthanides) can produce a near-ideal HER reaction path to adsorb H O and release H , respectively. Experimentally, the as-synthesized (Gd La )BaCo O outperforms the state-of-the-art Pt/C catalyst in many aspects. The proof-of-concept results reveal that the simultaneous possession of ordered oxygen vacancies and an appropriate number of OLH can realize a near-optimal synergistic catalytic effect, which is pivotal for rational design of oxygen-containing materials.

Titanium dioxide mesoporous microspheres with high surface area was successfully prepared by a facile one-step hydrothermal approach using polyethylene glycol (PEG, MW 200) as the soft template. Study shows that ∼15 nm TiO2 nanoparticles was assembled into ∼1.1 μm mesoporous microspheres. The Brunauer-Emmett-Teller surface area of TiO2 microsphere is up to 137 m2/g. TiO2 mesoporous microspheres were fabricated onto the surface of fluorine-doped tin oxide glass and used as the photoanode of dye-sensitized solar cells, which exhibits an open circuit photovoltage of 0.80 V and an overall conversion efficiency of 6.6%. Owing to the enhanced dye loading and light-harvesting efficiency, a 26% improvement in the overall conversion efficiency was achieved when compared with the commercial Degussa P25 nanoparticles.

Preparation of micro-lotus constructed by hierarchically porous Fe-doped ZnO nanosheets via a facile hydrothermal method is reported here. The products have been analyzed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and high resolution transmission electron microscope (HRTEM). Results showed that the morphology of the sample did not change with the Fe doping amount. The photoluminescence (PL) spectra revealed the existence of oxygen vacancies in the Fe-doped ZnO porous nanosheets, which is beneficial to the adsorption of oxygen and gas response, resulting in the improved performances in the later gas sensing experiments towards several reductive gases. The effect of Fe doping percentage on the gas response has also been investigated. We found that ZnO sample with Fe doping atomic percentage of 1% showed the highest gas sensing performance, while excessive Fe doping in ZnO suppressed the gas sensing response. A possible mechanism of how Fe-doped ZnO-based sensor responses to the target gas is also proposed.

Novel microsphere assembly of multi-sized TiO 2 branched nanorods were successfully fabricated via a hydrothermal method. We demonstrate the direct formation of CdS QDs on TiO 2 microspheres films by sequential chemical bath deposition. The as-prepared film was characterized by X-ray diffractmeter (XRD), scanning electron microscopy (SEM), Field-emission scanning electron microscopy (FE-SEM) and UV–vis absorption spectroscopy. Study show CdS sensitized branched TiO 2 multisized nanorods film electrode have a better solar cell performance with a high open-circuit photovoltage of 0.68 V, a short-circuit current of 2.53 mA/cm 2 and a conversion efficiency of 0.71%.

In this study, TiO 2 wedgy nanotubes with rectangular cross-sections were fabricated on transparent conductive substrates by using TiO 2 nanorods as the precursor via the anisotropic etching route. TiO2 nanotubes with V-shaped hollow structure and the special crystal plane exposed on the tube wall possess nature of high surface area for more dye molecules absorption, and the strong light scattering effects and dual-channel for effective electron transport of the TiO 2 V-shaped nanotubes based dye-sensitized solar cell exhibit a remarkable photovoltaic enhancement compared with the TiO 2 nanorods. The photoanode based on our V-shaped TiO 2 nanotubes with a length of 1.5 μm show a 123% increase of the dye loading and a 182% improvement in the overall conversion efficiency when compared with 4 μm rutile TiO 2 nanorods photoanode.