Abstract
Interest in low-temperature operation of solid oxide fuel cells is growing. Recent advances in perovskite phases have resulted in an efficient H
+
/O
2-
/e
-
triple-conducting electrode BaCo
...0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
for low-temperature fuel cells. Here, we further develop BaCo
0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
for electrolyte applications by taking advantage of its high ionic conduction while suppressing its electronic conduction through constructing a BaCo
0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
-ZnO p-n heterostructure. With this approach, it has been demonstrated that BaCo
0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
can be applied in a fuel cell with good electrolyte functionality, achieving attractive ionic conductivity and cell performance. Further investigation confirms the hybrid H
+
/O
2-
conducting capability of BaCo
0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
-ZnO. An energy band alignment mechanism based on a p-n heterojunction is proposed to explain the suppression of electronic conductivity and promotion of ionic conductivity in the heterostructure. Our findings demonstrate that BaCo
0.4
Fe
0.4
Zr
0.1
Y
0.1
O
3-δ
is not only a good electrode but also a highly promising electrolyte. The approach reveals insight for developing advanced low-temperature solid oxide fuel cell electrolytes.
A
bstract
We propose a method to compute the scattering angle for classical black hole scattering directly from two massive particle irreducible diagrams in a heavy-mass effective field theory ...approach to general relativity, without the need of subtracting iteration terms. The amplitudes in this effective theory are constructed using a recently proposed novel colour-kinematic/double copy for tree-level two-scalar, multi-graviton amplitudes, where the BCJ numerators are gauge invariant and local with respect to the massless gravitons. These tree amplitudes, together with graviton tree amplitudes, enter the construction of the required
D
-dimensional loop integrands and allow for a direct extraction of contributions relevant for classical physics. In particular the soft/heavy-mass expansions of full integrands is circumvented, and all iterating contributions can be dropped from the get go. We use this method to compute the scattering angle up to third post-Minkowskian order in four dimensions, including radiation reaction contributions, also providing the expression of the corresponding integrand in
D
dimensions.
The coupling nature of thermoelectric properties determines that optimizing the Fermi level is the priority to achieve a net increase in thermoelectric performance. Conventionally, the carrier ...concentration is used as the reflection of the Fermi level in the band structure. However, carrier concentration strongly depends upon the material’s effective mass, leading to that the optimal carrier concentration varies over a large scale for different materials. Herein, inspired by the big data survey, we develop a golden Seebeck coefficient range of 202–230 μV K–1 for thermoelectric semiconductors with lattice thermal conductivity of 0.4–1.5 W m–1 K–1. When the measured Seebeck coefficient reaches this range, the corresponding figure of merit is maximized. Using this approach, we exemplarily analyze the characteristics of n-type Pb1–x Bi x Se thermoelectric materials. With detailed electron microscopy and property characterizations, the high densities of dislocations and pores are found to be responsible for a low lattice thermal conductivity. Moreover, Bi substitution significantly tunes the Seebeck coefficient in a wide range. As a result, the Seebeck coefficient of ∼ –230 μV K–1 in Pb0.98Bi0.02Se is close to the golden range, leading to a figure of merit beyond 1.5. This finding provides an intuitive metric to determine the optimization extent of thermoelectric performance.
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With the ever-growing development of multifunctional and miniature electronics, the exploring of high-power microwatt-milliwatt self-charging technology is highly essential. Flexible ...thermoelectric materials and devices, utilizing small temperature difference to generate electricity, exhibit great potentials to provide the continuous power supply for wearable and implantable electronics. In this review, we summarize the recent progress of flexible thermoelectric materials, including conducting polymers, organic/inorganic hybrid composites, and fully inorganic materials. The strategies and approaches for enhancing the thermoelectric properties of different flexible materials are detailed overviewed. Besides, we highlight the advanced strategies for the design of mechanical robust flexible thermoelectric devices. In the end, we point out the challenges and outlook for the future development of flexible thermoelectric materials and devices.
We investigate silicon nanohole arrays as light absorbing structures for solar photovoltaics via simulation. To obtain the same ultimate efficiency as a standard 300 μm crystalline silicon wafer, we ...find that nanohole arrays require twelve times less silicon by mass. Moreover, our calculations show that nanohole arrays have an efficiency superior to nanorod arrays for practical thicknesses. With well-established fabrication techniques, nanohole arrays have great potential for efficient solar photovoltaics.
Due to its similar elastic modulus of human bones, polyetheretherketone (PEEK) has been considered as an excellent cytocompatible material. However, the bioinertness, poor osteoconduction, and weak ...antibacterial activity of PEEK limit its wide applications in clinics. In this study, a facile strategy is developed to prepare graphene oxide (GO) modified sulfonated polyetheretherketone (SPEEK) (GO‐SPEEK) through a simple dip‐coating method. After detailed characterization, it is found that the GO closely deposits on the surface of PEEK, which is attributed to the π–π stacking interaction between PEEK and GO. Antibacterial tests reveal that the GO‐SPEEK exhibits excellent suppression toward Escherichia coli. In vitro cell attachment, growth, differentiation, alkaline phosphatase activity, quantitative real‐time polymerase chain reaction analyses, and calcium mineral deposition all illustrate that the GO‐SPEEK substrate can significantly accelerate the proliferation and osteogenic differentiation of osteoblast‐like MG‐63 cells compared with those on PEEK and SPEEK groups. These results suggest that the GO‐SPEEK has an improved antibacterial activity and cytocompatibility in vitro, showing that the developed GO‐SPEEK has a great potential as the bioactive implant material in bone tissue engineering.
A facile strategy is used to produce a novel graphene oxide (GO) decorated sulfonated polyetheretherketone (SPEEK) biomaterial through dip‐coating approach. The results demonstrate that the GO is successfully absorbed on the SPEEK surface through π–π stacking interaction, and the biomaterial exhibits superior antibacterial ability, cytocompatibility, and osteogenic activity.
Liquid vinyl monomers were converted into solid crystals via halogen bonding. They underwent solid‐phase radical polymerizations through heating at 40 °C or ultraviolet photo‐irradiation (365 nm). ...The X‐ray crystallography analysis showed the high degree of monomer alignment in the crystals. The polymerizations of the solid monomer crystals yielded polymers with high molecular weights and relatively low dispersities because of the high degree of the monomer alignment in the crystal. As a unique application of this system, the crystalized monomers were assembled to pre‐determined structures, followed by solid‐phase polymerization, to obtain a two‐layer polymer sheet and a three‐dimensional house‐shaped polymer material. The two‐layer sheet contained a unique asymmetric pore structure and exhibited a solvent‐responsive shape memory property and may find applications to asymmetric membranes and polymer actuators.
Liquid vinyl monomers were converted into solid crystals via halogen bonding. They underwent solid‐phase radical polymerization, yielding polymers with high molecular weights and relatively low dispersities. The monomer crystals were assembled to pre‐determined structures, followed by solid‐phase polymerization, to yield polymer materials with complex structures.
The perovskite SrNb0.1Co0.7Fe0.2O3−δ (SNCF) is a promising OER electrocatalyst for the oxygen evolution reaction (OER), with remarkable activity and stability in alkaline solutions. This catalyst ...exhibits a higher intrinsic OER activity, a smaller Tafel slope and better stability than the state‐of‐the‐art precious‐metal IrO2 catalyst and the well‐known BSCF perovskite. The mass activity and stability are further improved by ball milling. Several factors including the optimized eg orbital filling, good ionic and charge transfer abilities, as well as high OH− adsorption and O2 desorption capabilities possibly contribute to the excellent OER activity.
The perovskite SrNb0.1Co0.7Fe0.2O3−δ shows remarkable activity and stability as an electrocatalyst for the oxygen evolution reaction in alkaline solutions. This catalyst has a smaller Tafel slope and better stability than the state‐of‐the‐art precious‐metal IrO2 catalyst and the well‐known BSCF perovskite. The mass activity and stability are further improved by ball milling. Sr purple, Co(Fe,Nb) red/yellow, O green/pale and dark blue.
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