Abstract
Exploring new near-room-temperature thermoelectric materials is significant for replacing current high-cost Bi
2
Te
3
. This study highlights the potential of Ag
2
Se for wearable ...thermoelectric electronics, addressing the trade-off between performance and flexibility. A record-high
ZT
of 1.27 at 363 K is achieved in Ag
2
Se-based thin films with 3.2 at.% Te doping on Se sites, realized by a new concept of doping-induced orientation engineering. We reveal that Te-doping enhances film uniformity and (00
l
)-orientation and in turn carrier mobility by reducing the (00
l
) formation energy, confirmed by solid computational and experimental evidence. The doping simultaneously widens the bandgap, resulting in improved Seebeck coefficients and high power factors, and introduces Te
Se
point defects to effectively reduce the lattice thermal conductivity. A protective organic-polymer-based composite layer enhances film flexibility, and a rationally designed flexible thermoelectric device achieves an output power density of 1.5 mW cm
−2
for wearable power generation under a 20 K temperature difference.
Abstract Germanium telluride (GeTe) with ultrafast ferroelectric transition, Rashba‐like electronic transport, and anomalous phonon anharmonicity are historically studied for potential memorizing and ...thermoelectric applications. Due to recent breakthroughs in spintronics, valleytronics, orbitronics, pre‐eminent GeTe thermoelectrics have re‐attracted enormous interest from both academia and industries, with increasing reports of significant figure‐of‐merit over 2.7 and the maximum efficiency of up to 17.0%. Here, the emerging trends in advancing GeTe thermoelectrics, starting from fundamentals of phase transformation, crystal structure, bonding mechanisms, and transport characteristics, with a highlight on the roles of Ge_4 s 2 lone pairs, are timely overviewed. Technical insights in synthesis, characterization, property measurement, and computation are then summarized. After that, several innovative strategies for increasing the figure‐of‐merit, including entropy engineering, nanostructuring, and hybridization, which will further benefit near‐room‐temperature and n‐type performance, are examined. Moreover, high‐density and high‐efficiency devices with broad working temperatures are discussed as a result of rational configurational and interfacial design. In the end, perspective remarks on the challenges and outlook envisaging for next‐generation GeTe thermoelectrics, which will play a prominent role in future energy and environmental landscapes, are provided.
Bi2Te3‐based thin films are attracting increasing attention due to their considerable wearability and flexibility feature. However, the relatively low performance compared to their bulk counterparts ...limits their development and wider application. In this work, synergistic texturing and Bi/Sb‐Te antisite doping are used to achieve a high room‐temperature ZT of ≈1.5 in p‐type Bi0.5Sb1.5Te3 thin films by a magnetron sputtering method. Structural characterization confirms that carefully tuning the deposition temperature can strengthen the texture of as‐prepared polycrystalline Bi0.5Sb1.5Te3 thin films, leading to significantly enhanced carrier mobility and electrical conductivity. Simultaneously, rational engineering of the deposition temperature can induce antisite doping between Bi/Sb and Te, which can reduce the carrier concentration and make it closer to the optimized level. In turn, a high power factor of 45.3 µW cm−1 K−2 and a maximized ZT of ≈1.5 at room temperature are obtained. This high power factor and ZT are highly competitive to other state‐of‐the‐art p‐type thin‐film‐based thermoelectric materials, showing great potentials for practical applications.
A high thermoelectric figure‐of‐merit ZT of ≈1.5 at room temperature in p‐type polycrystalline Bi0.5Sb1.5Te3 thin films by a synergy of texturing and Bi/Sb‐Te antisite doping is reported.
The discovery of novel succinate dehydrogenase inhibitors (SDHIs) has attracted great attention worldwide. Herein, a fragment recombination strategy was proposed to design new SDHIs by understanding ...the ligand–receptor interaction mechanism of SDHIs. Three fragments, pyrazine from pyraziflumid, diphenyl-ether from flubeneteram, and a prolonged amide linker from pydiflumetofen and fluopyram, were identified and recombined to produce a pyrazine-carboxamide-diphenyl-ether scaffold as a new SDHI. After substituent optimization, compound 6y was successfully identified with good inhibitory activity against porcine SDH, which was about 2-fold more potent than pyraziflumid. Furthermore, compound 6y exhibited 95% and 80% inhibitory rates against soybean gray mold and wheat powdery mildew at a dosage of 100 mg/L in vivo assay, respectively. The results of the present work showed that the pyrazine-carboxamide-diphenyl-ether scaffold could be used as a new starting point for the discovery of new SDHIs.
Owing to the moderate energy offset between light and heavy band edges of the rock‐salt structured GeTe, its figure‐of‐merit (ZT) can be enhanced by the rational manipulation of electronic band ...structures. In this study, density functional theory calculations are implemented to predict that V is an effective dopant for GeTe to enlarge the bandgap and converge the energy offset, which suppresses the bipolar conduction and increases the effective mass. Experimentally, V‐doped Ge1−xVxTe samples are demonstrated to have an enhanced Seebeck coefficient from ≈163 to ≈191 µV K−1. Extra alloying with Bi in Ge1−x−yVxBiyTe can optimize the carrier concentration to further enhance the Seebeck coefficient up to ≈252 µV K−1, plus an outstanding power factor of ≈43 µW cm−1 K−2. Comprehensive structural characterization results also verify the refinement of grain size by V‐doping, associated with highly dense grain boundaries, stacking faults, nanoprecipitates, and point defects, reinforcing the wide‐frequency phonon scattering and in turn, securing an ultralow thermal conductivity of ≈0.59 W m−1 K−1. As a result, the Ge0.9V0.02Bi0.08Te sample shows a peak ZT of >2.1 at 773 K, with an average plateaued average ZT of >2.0 from 623 and 773 K, which extends better thermoelectric behavior for GeTe over a wider temperature range. This study clarifies the multiple benefits of V‐doping in GeTe‐based derivatives and provides a framework for a new‐type of high‐performance middle‐temperature thermoelectric material.
The versatile benefits of Vanadium‐doping in a GeTe matrix are revealed, such as modulating the crystal symmetry, grain refining and band structure engineering, which enhance the power factor and suppress the thermal conductivity. With further Bi doping to tune carrier concentration, a high figure‐of‐merit of >2.1 is achieved in Ge0.9V0.02Bi0.08Te.
Cortisol is a reliable biomarker to evaluate human stress, as excessive stress can lead to an increased risk of cardiovascular diseases, neurogenic diseases, and sudden death. Therefore, it is ...necessary and important to seek a convenient and fast approach to detect cortisol, which is a great challenge. Herein, a novel four-fold interpenetrated framework {Eu(BTB)(H
2
O)
3
·1.5DMA·5H
2
O}
n
(
MHT-1
) was constructed and structurally characterized. The highly interpenetrated framework of
MHT-1
endows it with high thermal, solvent and pH stabilities. Notably,
MHT-1
can selectively detect cortisol with a wide concentration range from 10
−9
M to 4 × 10
−3
M in artificial human sweat. The corresponding sensitivity limit of
MHT-1
can reach 10
−9
M, which is a comparable value among those of other reported studies. In addition,
MHT-1
can repeatedly detect cortisol at least 20 times without an obvious loss of sensing sensitivity. More importantly, an intelligent logic gate has been designed, providing a simple approach to detect cortisol levels in human sweat with the naked eye. This work offers a novel luminescent MOF and a technique to achieve the visual and simple detection of cortisol in human sweat with a promising practical application.
A four-fold interpenetrated Ln-MOF (
MHT-1
) exhibits the excellent luminescence response to the stress biomarker cortisol, in which an intelligent logic gate based on
MHT-1
offers a simple approach to detect cortisol with the naked eye.
Recently, 2D organic–inorganic hybrid lead halide perovskites have attracted intensive attention in solid‐state luminescence fields such as single‐component white‐light emitters, and rational ...optimization of the photoluminescence (PL) performance through accurate structural‐design strategies is still significant. Herein, by carefully choosing homologous aliphatic amines as templates, isotypical perovskites DMEDAPbCl4 (1, DMEDA=N,N‐dimethylethylenediamine) and DMPDAPbCl4 (2, DMPDA=N,N‐dimethyl‐1,3‐diaminopropane) having tunable and stable broadband bluish white emission properties were rationally designed. The subtle regulation of organic cations leads to a higher degree of distortion of the 2D PbCl42− layers and enhanced photoluminescence quantum efficiencies (<1 % for 1 and 4.9 % for 2). The broadband light emissions could be ascribed to self‐trapped excitons on the basis of structural characterization, time‐resolved PL, temperature‐dependent PL emission, and theoretical calculations. This work gives a new guidance to rationally optimize the PL properties of low‐dimensional halide perovskites and affords a platform to probe the structure–property relationship.
Shining white: With the aim of optimizing the broadband white‐light emission performance of low‐dimensional perovskites, isomorphic 2D perovskites DMEDAPbCl4 and DMPDAPbCl4 were structurally designed on the basis of homologous amine templates. The subtle regulation of organic cations leads to increased distortion of the 2D PbCl42− layers and enhancement of the photoluminescence quantum efficiency from <1 to 4.9 %. DMEDA: dimethylethylenediamine, DMPDA: N,N‐dimethyl‐1,3‐diaminopropane.
•Effects of organic loading rate on anaerobic digestion of macroalgae were studied.•The growing organic loading rate in an appropriate range could improve biogas yield.•The overrange organic loading ...rate could cause system instability.•Unfavorable VFAs concentration, pH and salinity might be main causes for instability.•Several bacterial and archaeal phyla altered with growing OLR apparently.
Macroalgae biomass has been considered as a promising feedstock for biogas production. In order to improve the efficiency of anaerobic digestion (AD) of macroalgae, semi-continuous fermentation was conducted to examine the effects of organic loading rate (OLR) on biogas production from Macrocystis pyrifer. Results showed that, under OLRs of 1.37, 2.74, 4.12 and 6.85kgVSsubstrate/(m3·d), the average unit biogas yields were 438.9, 477.3, 480.1 and 188.7mL/(gVSsubstrated), respectively. It indicated that biogas production was promoted by the increased OLR in an appropriate range while inhibited by the OLR beyond the appropriate range. The investigation on physical-chemical parameters revealed that unfavorable VFAs concentration, pH and salinity might be the main causes for system failure due to the overrange OLR, while the total phenols failed to reach the inhibitory concentration. Microbial community analysis demonstrated that several bacterial and archaeal phyla altered with increase in OLR apparently.
pH value is a key parameter in reflecting the health status, reaction process, and water quality. The construction of highly sensitive pH luminescent ratiometric is important but challenging. Herein ...we designed and synthesized a unique triple-interpenetrated luminescent lanthanide-organic framework {Eu(PPTA)0.5(NO3)(DMF)2·H2O} n (V104) based on an amphoteric ligand 4,4′,4′′,4′′′-(1,4-phenylenebis(pyridine-4,2,6-triyl))tetrabenzoic acid (H4PPTA). Compound V104 possesses high solvent and acid/alkaline stabilities. Luminescent investigations reveal that V104 exhibits dual emission peaks at 390 and 480 nm, and these two peaks can separately detect OH– and H+ among various anions and cations. Importantly, V104 can serve as a self-calibrated pH ratiometric to quantitatively detect pH value, and the sensitivity can reach 403.2% per pH for OH–, and 129.5% per pH for H+. Furthermore, by encapsulating magnetic γ-Fe2O3 nanoparticles in V104, the pH sensor can be readily separated from the analyte by external magnet and recycled at least four times, suggesting as-synthesized γ-Fe2O3@V104 has potential for monitoring pH fluctuations in water. To our knowledge, this is the first self-calibrated ratiometric pH-sensor based on two responsive wave bands which can separately detect OH– and H+.
Mn alloying in thermoelectrics is a long‐standing strategy for enhancing their figure‐of‐merit through optimizing electronic transport properties by band convergence, valley perturbation, or ...spin‐orbital coupling. By contrast, mechanisms by which Mn contributes to suppressing thermal transports, namely thermal conductivity, is still ambiguous. A few precedent studies indicate that Mn introduces a series of hierarchical defects from the nano‐ to meso‐scale, leading to effective phonon scattering scoping a wide frequency spectrum. Due to insufficient insights at the atomic level, the theory remains as phenomenological and cannot be used to quantitatively predict the thermal conductivity of Mn‐alloyed thermoelectrics. Herein, by choosing the SnTe as a case study, aberration‐corrected transmission electron microscopy (TEM)/scanning transmission electron microscopy (STEM) to characterize the lattice complexity of Sn1.02−xMnxTe is employed. Mn as a “dynamic” dopant that plays an important role in SnTe with respect to different alloying levels or post treatments is revealed. The results indicate that Mn precipitates at x = 0.08 prior to reaching solubility (≈10 mol%), and then splits into MnSn substitution and γ‐MnTe hetero‐phases via mechanical alloying. Understanding such unique crystallography evolution, combined with a modified Debye‐Callaway model, is critical in explaining the decreased thermal conductivity of Sn1.02−xMnxTe with rational phonon scattering pathways, which should be applicable for other thermoelectric systems.
Structural evolution induced by Mn alloying is comprehensively investigated in thermoelectric materials, selecting SnTe as a case study. Comprehensive electron microscopy investigations indicate that, through rational structural manipulation, multiscale crystal imperfections are introduced as phonon scattering sources and in turn renders a high thermoelectric performance.
