Search

As a derivative of GeTe and MnTe, GeMnTe2 exhibits a cubic structure with no phase transition. Compared to GeTe, it is considerably cheaper and has a significantly high carrier concentration compared to MnTe, making it an excellent thermoelectric (TE) material with promising applications. Herein, a charge‐balanced vacancy engineering strategy is employed, resulting in a significant improvement in the power factor of GeMnTe2. Furthermore, the density functional theory calculation shows that the doping of Bi and the absence of Ge synergically increase the density of states near the Fermi level. Power factors of ≈13.7 μW cm−1 K−2 are achieved at 8% Bi content, a 22% improvement compared to the undoped system, while a final maximum ZT value of about 1.12 and an average ZT value of 0.72 are achieved. This indicates that charge‐balance vacancy engineering is an effective optimization method for the GeMnTe2 system, which can effectively improve the TE performance. [ABSTRACT FROM AUTHOR]

Graphical abstract A novel near-infrared fluorescent probe for colorimetric and sequential detection of Cu2+/S2− was designed and developed. Highlights • A new near-infrared fluorescent probe for sequential and reversible detection of Cu2+ and S2− was constructed. • Probe exhibited good selectivity, lower detection limit, and a large Stokes shift of 234 nm. • The proposed sensing mechanism was confirmed by DFT calculations and contrastive compound research. • The probe was successfully applied to detect Cu2+ in real water samples and strip papers. Abstract Copper ions (Cu2+) and sulfide (S2−) are important markers in many physiologies and pathological processes. In this work, a new near-infrared fluorescent probe 1 for colorimetric and sequential detection of Cu2+/S2− was designed and developed. The probe showed a rapid (less than 1 min), highly selective and sensitive response toward copper ions. Notably, the probe could also be applied to detect S2− through reversible formation-separation of complex 1 -Cu2+ and CuS with a large Stokes shift of 234 nm. The detection limit for Cu2+ and S2− was found to be 1.8 × 10-8 M and 1.5 × 10-8 M, respectively. Furthermore, the binding stoichiometry between 1 and Cu2+ was found to be 1:1, the binding mode was also demonstrated using density functional theory (DFT) calculations and contrastive compound research. In addition, the probe was successfully applied in real water samples assay for the detection of Cu2+, and the strip papers experiments also showed that probe 1 can be used to detect Cu2+ and S2−. [ABSTRACT FROM AUTHOR]

As a derivative of GeTe and MnTe, GeMnTe2 exhibits a cubic structure with no phase transition. Compared to GeTe, it is considerably cheaper and has a significantly high carrier concentration compared to MnTe, making it an excellent thermoelectric (TE) material with promising applications. Herein, a charge‐balanced vacancy engineering strategy is employed, resulting in a significant improvement in the power factor of GeMnTe2. Furthermore, the density functional theory calculation shows that the doping of Bi and the absence of Ge synergically increase the density of states near the Fermi level. Power factors of ≈13.7 μW cm−1 K−2 are achieved at 8% Bi content, a 22% improvement compared to the undoped system, while a final maximum ZT value of about 1.12 and an average ZT value of 0.72 are achieved. This indicates that charge‐balance vacancy engineering is an effective optimization method for the GeMnTe2 system, which can effectively improve the TE performance. [ABSTRACT FROM AUTHOR]

Hydrogen and hydrogen-injected natural gas have been vigorously developed. However, H 2 can cause hydrogen embrittlement of pipeline steel during transportation. To investigate the mechanism of CO suppression of hydrogen embrittlement in pipeline steels, this work utilizes the first-principles method of density functional theory (DFT) to explore the impact of CO on H 2 dissociation and H diffusion processes on Fe(100) and Fe(110) surfaces. Adsorption of CO reduces the charge density around Fe atoms, with the surface charge density of (110) reduced to a greater extent. The planar-average charge density shows that the change in charge density is primarily focused near the interface, where charge of the matrix Fe atom is partially transferred to C atom of CO molecule. An increase in the dissociation energy barrier shows that CO has an inhibitory effect on the dissociation of H 2. In addition, CO can hinder H atom diffusion on the Fe surface. Among them, the hindrance of penetration from surface to interior of the bulk structure is the most obvious, and the strength of hindrance also depends on how close the CO is to the H atom. This study theoretically explains the inhibition mechanism of CO on hydrogen embrittlement of pipeline steel. [ABSTRACT FROM AUTHOR]

Abstract: Ab initio calculations have been performed on Fe/Mo(100) superlattices in order to study the interfacial magnetic properties and layer thickness effect on the magnetic moments. In most cases, the magnetic moments of interfacial Fe monolayers are always smaller than those of the inner layers, and the induced magnetic moments of interfacial Mo monolayers oriented in the opposite direction. Calculation results show that the Fe layers are ferromagnetic when n =3. As the thickness of the Mo layers increases, the influence of the Mo layer increases and the magnetic state of the Fe layer gradually changes into an antiferromagnetic or non-magnetic state. The change of magnetic moments of Fe/Mo superlattices is in agreement with the experimentally observed oscillation periods. [Copyright &y& Elsevier]

• A three-dimensional Ni,Co-embedded CNT-coated N-doped hollow porous carbon (Ni/Co-CNT/NHPC) cathode has been designed and prepared for lithium-sulfur battery. • The Ni/Co-CNT/NHPC-S cathode possesses a high specific capacity of 1352 mA h g-1 and an excellent cycle stability at 1 C with low capacity decay of 0.094% per cycle over 500 cycles. • The mechanism of suppressing the shuttle effect on the cathode materials is discussed by analyzing adsorption experiments and density functional theory（DFT）calculation. Lithium-sulfur (Li-S) batteries have attracted great attentions due to their high specific capacity. However, the poor cycle stability caused by polysulfide shuttles, volume expansion and formation of lithium dendrites limit their practical applications. In the present work, to tackle the poor stability and unstable rate capability, a MOF-doping strategy is developed to construct a hollow porous carbon framework，which consists of Ni, Co particles and CNT on a N-doped shell surface (Ni/Co-CNT/NHPC). This hollow framework increases the load of S, slows down the volume changes, and can physically entrap soluble polysulfide. It is found that the CNT-coated network structure is beneficial for optimizing the conductivity and wettability of the material, which accelerates the reaction kinetics. Moreover, synergistic effect of abundant defects and Ni, Co nanoparticles strengthens the chemisorption of polysulfides, which suppresses the shuttle effect. As a consequence, the Ni/Co-CNT/NHPC-S cathode harvests a high specific capacity (1352 mA h g-1), and shows an excellent cycling stability at 1 C with low capacity decay of 0.094% over 500 cycles. [ABSTRACT FROM AUTHOR]