Search

Abstract The lack of desirable diffusion barrier layers currently prohibits the long-term stable service of bismuth telluride thermoelectric devices in low-grade waste heat recovery. Here we propose a new design principle of barrier layers beyond the thermal expansion matching criterion. A titanium barrier layer with loose structure is optimized, in which the low Young’s modulus and particle sliding synergistically alleviates interfacial stress, while the TiTe2 reactant enables metallurgical bonding and ohmic contact between the barrier layer and the thermoelectric material, leading to a desirable interface characterized by high-thermostability, high-strength, and low-resistivity. Highly competitive conversion efficiency of 6.2% and power density of 0.51 W cm−2 are achieved for a module with leg length of 2 mm at the hot-side temperature of 523 K, and no degradation is observed following operation for 360 h, a record for stable service at this temperature, paving the way for its application in low-grade waste heat recovery.

In recent years, the advancement of photovoltaic power generation technology has led to a surge in the construction of photovoltaic power stations in desert gravel areas. However, traditional equal cross-section photovoltaic bracket pile foundations require improvements to adapt to the unique challenges of these environments. This paper introduces a new type of photovoltaic bracket pile foundation named the “serpentine pile foundation” based on the principle of biomimicry. Utilizing experimental data, numerical simulation technology was employed to comprehensively investigate the pullout resistance, compressive resistance, and horizontal bearing performance of the serpentine pile foundation. Comparative analysis with traditional square and circular pile foundations revealed the serpentine pile foundation’s significant advantages in all performance indexes. The serpentine pile exhibits a significantly higher ultimate uplift bearing capacity of 70.25 kN, which is 8.56 times that of the square pile and 10.94 times that of the circular pile. This study not only offers valuable technical support for the construction of photovoltaic power plants in desert gravel areas but also holds great significance in advancing the sustainable development of the global photovoltaic industry.

IntroductionSystemic Lupus Erythematosus (SLE) impacts the central nervous system (CNS), leading to severe neurological and psychiatric manifestations known as neuropsychiatric lupus (NPSLE). The complexity and heterogeneity of clinical presentations of NPSLE impede direct investigation of disease etiology in patients. The limitations of existing mouse models developed for NPSLE obstruct a comprehensive understanding of this disease. Hence, the identification of a robust mouse model of NPSLE is desirable.MethodsC57BL/6 mice transgenic for human MeCP2 (B6.Mecp2Tg1) were phenotyped, including autoantibody profiling through antigen array, analysis of cellularity and activation of splenic immune cells through flow cytometry, and measurement of proteinuria. Behavioral tests were conducted to explore their neuropsychiatric functions. Immunofluorescence analyses were used to reveal altered neurogenesis and brain inflammation. Various signaling molecules implicated in lupus pathogenesis were examined using western blotting.ResultsB6.Mecp2Tg1 exhibits elevated proteinuria and an overall increase in autoantibodies, particularly in female B6.Mecp2Tg1 mice. An increase in CD3+CD4+ T cells in the transgenic mice was observed, along with activated germinal center cells and activated CD11b+F4/80+ macrophages. Moreover, the transgenic mice displayed reduced locomotor activity, heightened anxiety and depression, and impaired short-term memory. Immunofluorescence analysis revealed IgG deposition and immune cell infiltration in the kidneys and brains of transgenic mice, as well as altered neurogenesis, activated microglia, and compromised blood-brain barrier (BBB). Additionally, protein levels of various key signaling molecules were found to be differentially modulated upon MeCP2 overexpression, including GFAP, BDNF, Albumin, NCoR1, mTOR, and NLRP3.DiscussionCollectively, this work demonstrates that B6.Mecp2Tg1 mice exhibit lupus-like phenotypes as well as robust CNS dysfunctions, suggesting its utility as a new animal model for NPSLE.

Abstract Studies of vacancy-mediated anomalous transport properties have flourished in diverse fields since these properties endow solid materials with fascinating photoelectric, ferroelectric, and spin-electric behaviors. Although phononic and electronic transport underpin the physical origin of thermoelectrics, vacancy has only played a stereotyped role as a scattering center. Here we reveal the multifunctionality of vacancy in tailoring the transport properties of an emerging thermoelectric material, defective n-type ZrNiBi. The phonon kinetic process is mediated in both propagating velocity and relaxation time: vacancy-induced local soft bonds lower the phonon velocity while acoustic-optical phonon coupling, anisotropic vibrations, and point-defect scattering induced by vacancy shorten the relaxation time. Consequently, defective ZrNiBi exhibits the lowest lattice thermal conductivity among the half-Heusler family. In addition, a vacancy-induced flat band features prominently in its electronic band structure, which is not only desirable for electron-sufficient thermoelectric materials but also interesting for driving other novel physical phenomena. Finally, better thermoelectric performance is established in a ZrNiBi-based compound. Our findings not only demonstrate a promising thermoelectric material but also promote the fascinating vacancy-mediated anomalous transport properties for multidisciplinary explorations.

Highlights A hierarchical interconnected NiMoN (HW-NiMoN-2h) was successfully prepared based on a rational combination of hydrothermal and water bath processes. HW-NiMoN-2h exhibited high hydrogen evolution reaction (HER) activity due to its large specific surface area and good stability due to its enhanced mechanical strength. In 1 M KOH seawater, HW-NiMoN-2h delivered current density of 1 A cm−2 for HER at an overpotential of 130 mV and showed excellent stability over 70 h at 1 A cm−2.

Magnetic levitation for the transport of people and goods using bulk superconductors and electrical power transmission using superconductors have both been demonstrated, but neither has been developed for daily use due to technological deficiencies and high costs. We envision combining the transport of people and goods and energy transmission and storage in a single system. Such a system, built on existing highway infrastructure, incorporates a superconductor guideway, allowing for simultaneous levitation of vehicles with magnetized undercarriages for rapid transport without schedule limitations and lossless transmission and storage of electricity. Incorporating liquefied hydrogen additionally allows for simultaneous cooling of the superconductor guideway and sustainable energy transport and storage. Here, we report the successful demonstration of the primary technical prerequisite, levitating a magnet above a superconductor guideway.

Doping is central to solid-state devices and generally believed to hinder electron transport. Here, the authors show that certain dopants can cloak themselves from electrons and achieve higher mobility than the conventional limit.

Bi2Te3 based alloys have been the most widely used thermoelectric material at low temperature for many decades. Here we report Se doped n-type Mg3Bi2 based materials with a thermoelectric figure-of-merit ZT of 0.82 at 300 K and a peak ZT of 1.24 at 498 K, which is comparable to the n-type Bi2Te3 and Te doped Mg3Bi1.4Sb0.6. The improved thermoelectric performance is benefited from the high carrier concentration and mobility as well as the thermal conductivity reduction. The reduced resistivity increased the power factor at all measured temperatures, leading to a higher engineering ZT (ZTeng) and engineering power factor (PFeng) for n-type Mg3Bi2. The n-type Mg3Bi1.4Sb0.6 materials are promising for thermoelectric power generation and cooling applications near room temperature.

Though earth abundant magnesium-based materials are attractive for thermoelectrics (TEs) due to their device-level performance, realizing efficient modules remains a challenge. Here, the authors report a scalable route to realizing Mg-based compounds for high performance TE modules.

In order to optimize thermoelectric (TE) materials which are used to convert thermal energy and electrical energy, the underlying physics needs to be understood. Here, the authors show that by exploiting static local structure distortion, transverse acoustic phonons can be suppressed resulting in high performing TE materials.

Seawater electrolysis is a promising approach to produce hydrogen fuel and is also of great significance to seawater desalination. Here, the authors prepare 3D core-shell metal-nitride catalysts from earth-abundant elements for high-performance alkaline seawater electrolysis.

Large-scale-applicable thermoelectric materials should be both self-sustaining, in order to survive long-term duty cycles, and nonpolluting. Among all classes of known thermoelectric materials, these criteria reduce the available candidate pool, leaving silicon as one of the remaining options. Here we first review the thermoelectric properties of various silicon-related materials with respect to their morphologies and microstructures. We then report the thermoelectric properties of silicon sawing wastes recycled from silicon wafer manufacturing. We obtain a high power factor of ∼32 μW cm−1 K−2 at 1273 K with 6% phosphorus substitution in the Si crystal, a value comparable to that of phosphorus-doped silicon-germanium alloys. Our work suggests the large-scale thermoelectric applicability of recycled silicon that would otherwise contribute to the millions of tons of industrial waste produced by the semiconductor industry. Keywords: Silicon, Thermoelectric, Nanostructure, Power factor, Sawing waste

The discovery of thermodynamically stable thermoelectric materials for power generation has relied on empirical methods that were not effective. Here, the authors apply the inverse design approach to identify and experimentally realize TaFeSb-based half Heuslers with high thermoelectric performance.

In river management, it is important to obtain ice velocity quickly and accurately during ice flood periods. However, traditional ice velocity monitoring methods require buoys, which are costly and inefficient to distribute. It was found that UAV remote sensing images combined with machine vision technology yielded obvious practical advantages in ice velocity monitoring. Current research has mainly monitored sea ice velocity through GPS or satellite remote sensing technology, with few reports available on river ice velocity monitoring. Moreover, traditional river ice velocity monitoring methods are subjective. To solve the problems of existing time-consuming and inaccurate ice velocity monitoring methods, a new ice velocity extraction method based on UAV remote sensing technology is proposed in this article. In this study, the Mohe River section in Heilongjiang Province was chosen as the research area. High-resolution orthoimages were obtained with a UAV during the ice flood period, and feature points in drift ice images were then extracted with the scale-invariant feature transform (SIFT) algorithm. Moreover, the extracted feature points were matched with the brute force (BF) algorithm. According to optimization results obtained with the random sample consensus (RANSAC) algorithm, the motion trajectories of these feature points were tracked, and an ice displacement rate field was finally established. The results indicated that the average ice velocities in the research area reached 2.00 and 0.74 m/s, and the maximum ice velocities on the right side of the river center were 2.65 and 1.04 m/s at 16:00 on 25 April 2021 and 8:00 on 26 April 2021, respectively. The ice velocity decreased from the river center toward the river banks. The proposed ice velocity monitoring technique and reported data in this study could provide an effective reference for the prediction of ice flood disasters.

N-type Mg3Sb2-xBix alloys have been extensively studied in recent years due to their significantly enhanced thermoelectric figure of merit (zT), thus promoting them as potential candidates for waste heat recovery and cooling applications. In this review, the effects resulting from alloying Mg3Bi2 with Mg3Sb2, including narrowed bandgap, decreased effective mass, and increased carrier mobility, are summarized. Subsequently, defect-controlled electrical properties in n-type Mg3Sb2-xBix are revealed. On one hand, manipulation of intrinsic and extrinsic defects can achieve optimal carrier concentration. On the other hand, Mg vacancies dominate carrier-scattering mechanisms (ionized impurity scattering and grain boundary scattering). Both aspects are discussed for Mg3Sb2-xBix thermoelectric materials. Finally, we review the present status of, and future outlook for, these materials in power generation and cooling applications.

Electrochemical water splitting driven by clean and sustainable energy sources to produce hydrogen is an efficient and environmentally friendly energy conversion technology. Water splitting involves hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in which OER is the limiting factor and has attracted extensive research interest in the past few years. Conventional noble-metal-based OER electrocatalysts like IrO2 and RuO2 suffer from the limitations of high cost and scarce availability. Developing innovative alternative nonnoble metal electrocatalysts with high catalytic activity and long-term durability to boost the OER process remains a significant challenge. Among all of the candidates for OER catalysis, self-supported layered double hydroxides (LDHs) have emerged as one of the most promising types of electrocatalysts due to their unique layered structures and high electrocatalytic activity. In this review, we summarize the recent progress on self-supported LDHs and highlight their electrochemical catalytic performance. Specifically, synthesis methods, structural and compositional parameters, and influential factors for optimizing OER performance are discussed in detail. Finally, the remaining challenges facing the development of self-supported LDHs are discussed and perspectives on their potential for use in industrial hydrogen production through water splitting are provided to suggest future research directions.

Interrupted sampling repeater jamming (ISRJ) uses the under sampling technology to transmit and repeat the radar intercepted signals. As a new kind of coherent interference, it is widely used in self-defence interference. At the same time, the existing radar anti-jamming technology cannot effectively combat it. In this study, the principle of ISRJ is analysed. In view of the mismatch between the jamming signal and the radar transmitting signal, an orthogonal phase-frequency coded signal in a pulse is designed. In signal processing, matching and filtering are processed separately through each sub-signal. The simulation results show that the designed signal has a good inhibitory effect on ISRJ.

Identifying new compounds with intrinsically high conversion efficiency is the key to demonstrating next-generation thermoelectric modules. Here, Zhu et al. report the discovery of p-type ZrCoBi-based half Heuslers with thermoelectric conversion efficiency of 9% and large high-temperature stability.

Water electrolysis provides a carbon-neutral means to generate hydrogen fuel from water, but the process typically requires expensive, rare metal catalysts. Here, the authors prepare hydrogen- and oxygen-evolving electrocatalysts from earth-abundant elements that outperform noble-metal counterparts.

The intrinsic origin of high-power factors observed in half-Heusler alloys remains elusive, limiting the design of new thermoelectric materials. In this work, the authors reveal it is due to weakened electron–acoustic phonon coupling, originating from crystal symmetry protection of non-bonding orbitals.

A charge density wave (CDW) ground state is observed in polycrystalline Cu2Se below 125 K, which corresponds to an energy gap of 40.9 meV and an electron-phonon coupling constant of 0.6. Due to the polycrystalline structure, the Peierls transition process has been expanded to a wide temperature range from 90 K to 160 K. The Hall carrier concentration shows a continuous decrease from 2.1 × 1020 to 1.6 × 1020 cm−3 in the temperature range from 160 K to 90 K, while almost unchanged above 160 K and below 90 K. After entering the CDW ground state, a wave-like fluctuation was observed in the I-V curve near 50 K, which exhibits a periodic negative differential resistivity in an applied electric field due to the current. We also investigated the doping effect of Zn, Ni, and Te on the CDW ground state. Both Zn and Ni doped Cu2Se show a CDW character with increased energy gap and electron-phonon coupling constant, but no notable Peierls transition was observed in Te doped Cu2Se. Similar wave-like I-V curve was also seen in Cu1.98Zn0.02Se near 40 K. The regular fluctuation in the dc I-V curve was not magnetic field sensitive, but temperature and sample size sensitive.

In photovoltaics window electrodes must display uniform current transport, as well as high light transmission from the substrate. Here, Han et al.show that quasi-fractal metallic networks provide a practical realization of an electrode structure with an optimal surface coverage and a uniform current density.

There is on-going research into efficient noble metal-free materials for electrocatalytic hydrogen evolution. Here, the authors prepare ternary molybdenum sulfoselenide particles supported on three-dimensional porous nickel selenide foam, and demonstrate the high efficiency of the hydrogen evolving composite.

Band convergence is one of the most interesting topics in recent studies of thermoelectrics. However, its effect on thermoelectric properties is only simply stated as improving band degeneracy. In this paper, the enhanced thermoelectric performance due to band convergence is clarified from the viewpoint of distribution of carriers in the electronic bands. The n-type Mg2Sn0.75Ge0.25 is used as a case study, and the effect of band offset E on its thermoelectric properties is investigated based on the three-band model, i.e., one light conduction band, one heavy conduction band, and one valence band. The results show that E has a decisive effect on controlling the distribution of carriers in the two conduction bands, thus affecting the thermoelectric properties. Since the optimal carrier concentration nopt is related to the density of state effective mass m∗ at a given temperature, an appropriate distribution of carriers should be a higher carrier concentration in the heavy band (with larger m∗) and a lower carrier concentration in the light band (with smaller m∗). In order to achieve a proper distribution of carriers, E should be as small as possible at any temperature, which explains the reason why band convergence could lead to the enhanced thermoelectric performance.

Here we report the thermoelectric properties of NbCoSn-based n-type half-Heuslers (HHs) that were obtained through arc melting, ball milling, and hot pressing process. With 10% Sb substitution at the Sn site, we obtained enhanced n-type properties with a maximum power factor reaching ∼35 μW cm−1 K−2 and figure of merit (ZT) value ∼0.6 in NbCoSn0.9Sb0.1. The ZT is doubled compared to the previous report. In addition, the specific power cost ($ W−1) is decreased by ∼68% comparing to HfNiSn-based n-type HH because of the elimination of Hf.

NbCoSb with nominal 19 valence electrons, and is supposed to be metallic, has recently been reported to also exhibit the thermoelectric properties of a heavily doped n-type semiconductor. In this study, we prepared Co-rich NbCo1+xSb samples (x = 0, 0.2, 0.3, 0.4, 0.5), and their phase compositions, microstructures and thermoelectric properties were investigated. The Seebeck coefficient increased a great deal with increasing x, due to decreasing carrier concentration, and the total thermal conductivity reduced mainly because of declining κe. Finally, a peak thermoelectric figure of merit, ZT, was about 0.46 for NbCo1.3Sb at 973 K. This enhancement was mainly attributed to the reduction of electric thermal conductivity and the increase of Seebeck coefficient. The excess Co had effects on the carrier concentration, deformation potential Edef and DOS effective mass m*. Adding an excessive amount of Co leads to a very high Edef, which was detrimental for transport characteristics.

New TEM grids coated with ultrathin amorphous Al2O3 films have been developed using atomic layer deposition technique. The amorphous Al2O3 films can withstand temperatures over 600∘C in air and 900∘C in vacuum when the thickness of the Al2O3 film is 2 nm, and up to 1000∘C in air when the thickness is 25 nm, which makes heating TEM grids with nanoparticles up to 1000∘C in air and immediate TEM observation without interrupting the nanoparticles possible. Such coated TEM grids are very much desired for applications in high-temperature high-resolution transmission electron microscopy.

The effects of anisotropic superexchange and Fe–Fe hoppings on phase transitions in the undoped three-orbital spin-fermion model are investigated to understand the experimentally reported strain effect in BaFe _2 As _2 . Monte Carlo simulated phase diagrams show that both the collinear antiferromagnetic and nematic transitions shift toward high temperature with the increasing magnitude of anisotropies, qualitatively consistent with experimental observation. Thus, both the anisotropic superexchange and Fe–Fe hoppings are suggested to be responsible for the variation of the transition temperatures of BaFe _2 As _2 with uniaxial stress. In addition, we observed a 90 degree rotation of the collinear antiferromagnetic order, accompanied with a reversal of the orbital occupancy at the Fermi surface when the sign of the superexchange anisotropy changes, further supporting previous predictions by first principles calculation.

The undoped three-orbital spin-fermion model with the additional biquadratic interaction which arises from various factors, such as quantum or thermal fluctuation, is studied using the Monte Carlo method in order to investigate the spin orders in pnictide superconductors. The simulations show that the experimentally observed nematic state can be stabilized by the positive biquadratic interaction, suggesting that such interaction may be another origin for nematicity in pnictides in addition to the couplings to the lattice degrees of freedom. Furthermore, the so-called flux state at low temperatures is identified when a rather weak negative biquadratic interaction is introduced, which is the same as the phase predicted in earlier theoretical work.