Observation of Spin Splitting in Room-Temperature Metallic Antiferromagnet CrSb.

Recently, unconventional antiferromagnets that enable the spin splitting (SS) of electronic states have been theoretically proposed and experimentally realized, where the magnetic sublattices containing moments pointing at different directions are connected by a novel set of symmetries. Such SS is substantial, k-dependent, and independent of the spin-orbit coupling (SOC) strength, making these magnets promising materials for antiferromagnetic spintronics. Here, combined with angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations, a systematic study on CrSb, a metallic spin-split antiferromagnet candidate with Néel temperature TN = 703 K, is conducted. The data reveal the electronic structure of CrSb along both out-of-plane and in-plane momentum directions, rendering an anisotropic k-dependent SS that agrees well with the calculational results. The magnitude of such SS reaches up to at least 0.8 eV at non-high-symmetry momentum points, which is significantly higher than the largest known SOC-induced SS. This compound expands the choice of materials in the field of antiferromagnetic spintronics and is likely to stimulate subsequent investigations of high-efficiency spintronic devices that are functional at room temperature.

Large-Scale Synthesis of N,S Codoped Carbon-Modified Fe0.975S Composites as a Novel Anode for Lithium/Sodium Ion Batteries with Enhanced Performance.

To overcome obstacles hindering the commercialization of lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), we introduce a cost-effective single-step sulfurization strategy for synthesizing iron sulfide (Fe0.975S) nanohybrids, augmented by N,S codoped carbon. The resulting N,S codoped carbon-coated Fe0.975S (Fe0.975S@NSC) electrode exhibits exceptional potential as a highly reversible anode material for both LIBs and SIBs. With impressive initial discharge and charge capacities (1658.2 and 1254.9 mAh g-1 for LIBs and 1450.9 and 1077.1 mAh g-1 for SIBs), the electrode maintains substantial capacity retention (900 mA h g-1 after 1000 cycles for LIBs and 492.5 mA h g-1 after 600 cycles for SIBs at 1.0 A g-1). The LiMn2O4//Fe0.975S@NSC and Na3V2(PO4)3//Fe0.975S@NSC full batteries can maintain excellent reversible capacity and robust cycling stability. Ex situ and in situ X-ray diffraction, density functional theory (DFT) calculations, and kinetics analysis confirm the promising energy storage potential of the Fe0.975S@NSC composite.

Potential Water Collection From Air by Chloride Perovskites.

Directly capturing water from the air has become a compelling strategy to secure water resources. Yet, challenges persist with sorption-based hygroscopic materials, such as inadequate water adsorption efficiency, material degradation post-adsorption, and the need for energy input during water collection. This study introduces an alternative category of sorbent materials potentially for atmospheric water harvesting-metal chloride perovskites-that exhibit spontaneous water vapor adsorption and liquid water collection. This water uptake capability stems from the uncoordinated polar ions that form hydrogen bonds with water molecules, while the cubic lattice imparts a solid framework ensuring structural stability and inhibiting hydrolysis. The methylammonium lead chloride perovskite pellets exhibit efficient water collection performance, with a record absorption rate of 0.841 L m-2 h-1 and a total water collection of 3.675 L m-2 within a 7-h cycle. This initiative attempts to provide a new material class candidate for the potential application of passive atmospheric water harvesting.

Superlubric Graphullerene.

Graphullerene (GF), an extended quasi-two-dimensional network of C60 molecules, is proposed as a multicontact platform for constructing superlubric interfaces with layered materials. Such interfaces are predicted to present very small and comparable sliding energy corrugation regardless of the identity of the underlying flat layered material surface. It is shown that, beyond the geometrical effect, covalent interlinking between the C60 molecules results in reduction of the sliding energy barrier. For extended GF supercells, negligible sliding energy barriers are found along all sliding directions considered, even when compared to the case of the robust superlubric graphene/h-BN heterojunction. This suggests that multicontact architectures can be used to design ultrasuperlubric interfaces, where superlubricity may persist under extreme sliding conditions.

In-situ growth of a covalent organic framework-based matrix-compatible microextraction coating for sensitive extraction of multiple pesticides.

The potential pesticide hazard to non-target organisms is a global concern. It is critical to develop the sensitive detection methods of multiple pesticides in various complex matrices. Here, benzene-1,3,5-tricarbaldehyde (BTCA) and 1,3,5-Tri (4-aminophenyl) benzene (TAPB) were employed as precursors for the in-situ growth of COFTAPB-BTCA on the surface of amino-functionalized stainless steel wire (SS) via a solvothermal method. The successful COFTAPB-BTCA bonded fiber exhibited significant enrichment capability of pyrethroids insecticides (PYs), organophosphorus (OPPs), and organochlorine (OCPs), with enrichment factors (EFs) ranging from 1133-7762, 1319-7291, and 734.1-2882, respectively. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations indicated that various interactions contributed to its high enrichment capacity. Automated detection of PYs, OPPs, and OCPs in water, foods, and biological samples was realized by coupling this fiber with gas chromatography-mass spectrometry (GC-MS). The detection limits were as low as 0.0370-0.657 ng/L, 0.0128-0.400 ng/L, and 0.0329-0.202 ng/L for PYs, OPPs, and OCPs, respectively. In addition, the environmental risks of these samples were assessed based on the above data. This work not only provided a straightforward technique for sensitive monitoring of pesticides in complex matrices but also presented a novel approach for the in-situ controlled growth of versatile adsorbents with broad-spectrum properties.

Well-defined asymmetric nitrogen/carbon-coordinated single metal sites for carbon dioxide conversion.

Asymmetric nitrogen/carbon-coordinated single metal sites (M-NxC4-x) outperform symmetric M-N4 sites in carbon dioxide (CO2) electroreduction. However, the challenge of crafting well-defined M-NxC4-x sites complicates the understanding of their structure-catalytic performance relationship. In this study, we employ metallized N-confused tetraphenylporphyrin (M-NCTPP) to investigate CO2 conversion on M-N3C1 sites using both density functional theory and experimental methods. The optimal cobalt (Co)-N3C1 site (Co-NCTPP) achieves a current density of 500 mA cm-2 and a carbon monoxide Faraday efficiency exceeding 90 % at -1.25 V vs. the reversible hydrogen electrode, surpassing the performance of Co-N4 (Co-TPP). This research introduces a novel approach for designing and synthesizing high-activity heteroatom-anchored single metal sites, advancing fundamental understanding in the field.

Designing Organic Spin-Gapless Semiconductors via Molecular Adsorption on C4N3 Monolayer.

Spin-gapless semiconductor (SGS), a class of zero-gap materials with fully spin-polarized electrons and holes, offers significant potential for high-speed, low-energy consumption applications in spintronics, electronics, and optoelectronics. Our first-principles calculations revealed that the Pca21 C4N3 monolayer exhibits a ferromagnetic ground state. Its band structure displays SGS-like characteristics, with the energy gap between the valence and conduction bands near the Fermi level in the spin-down channel much smaller than the one in the other spin channel. To enhance its SGS properties, we introduced electrons into the Pca21 C4N3 monolayer by adsorbing the CO gas molecule on its surface. Stable gas adsorption (CO@C4N3) effectively narrowed the band gap in the spin-down channel without changing the band gap in the spin-up channel obviously. Moreover, injecting holes into the CO@C4N3 system could increase the net magnetic moments and induce an SGS-to-metallic phase transition, while injecting electrons into the CO@C4N3 system is able to lower the net magnetic moments and cause an SGS-to-half-metallic phase transition. Our findings not only underscore a new promising material for practical metal-free spintronics applications but also illustrate a viable pathway for designing SGSs.

Atomically Thin Kagome-Structured Co9Te16 Achieved through Self-Intercalation and Its Flat Band Visualization.

Kagome materials have recently garnered substantial attention due to the intrinsic flat band feature and the stimulated magnetic and spin-related many-body physics. In contrast to their bulk counterparts, two-dimensional (2D) kagome materials feature more distinct kagome bands, beneficial for exploring novel quantum phenomena. Herein, we report the direct synthesis of an ultrathin kagome-structured Co-telluride (Co9Te16) via a molecular beam epitaxy (MBE) route and clarify its formation mechanism from the Co-intercalation in the 1T-CoTe2 layers. More significantly, we unveil the flat band states in the ultrathin Co9Te16 and identify the real-space localization of the flat band states by in situ scanning tunneling microscopy/spectroscopy (STM/STS) combined with first-principles calculations. A ferrimagnetic order is also predicted in kagome-Co9Te16. This work should provide a novel route for the direct synthesis of ultrathin kagome materials via a metal self-intercalation route, which should shed light on the exploration of the intriguing flat band physics in the related systems.

Pt3Sn0.5Mn0.5 Intermetallic Electrocatalyst with Superior Stability for CO-Resilient Methanol Oxidation.

The sluggish kinetics of methanol oxidation reaction (MOR) and poor long-term durability of catalysts are the main restrictions of the large-scale applications of direct methanol fuel cells (DMFCs). Herein, we demonstrated an inspirational ternary Pt3Sn0.5Mn0.5/DMC intermetallic catalyst that reached 4.78 mA cm-2 and 2.39 A mg-1Pt for methanol oxidation, which were 2.50/2.44 and 5.62/5.31 times that of commercial PtRu/C and Pt/C. After the durability test, Pt3Sn0.5Mn0.5/DMC presented a very low current density attenuation (38.5%), which was significantly lower than those for commercial PtRu/C catalyst (84.2%) and Pt/C (93.1%). Density functional theory (DFT) calculations revealed that the coregulation of Sn and Mn altered the surface electronic structure and endowed Pt3Sn0.5Mn0.5 with selective adsorption of Pt for CO and Sn for OH, which optimized the adsorption strength for intermediates and improved the reaction kinetics of MOR. Beyond offering an advanced electrocatalyst, this study provided a new point of view for the rational design of superior methanol oxidation catalysts for DMFC.

The Influence of the Alkylamino Group on the Solvatochromic Behavior of 5-(4-substituted-arylidene)-1,3-dimethylpyrimidine-2,4,6-triones: Synthesis, Spectroscopic and Computational Studies.

Advances in electronics and medical diagnostics have made organic dyes extremely popular as key functional materials. From a practical viewpoint, it is necessary to assess the spectroscopic and physicochemical properties of newly designed dyes. In this context, the condensation of 1,3-dimethylbarbituric acid with electron-rich alkylaminobenzaldehyde derivatives has been described, resulting in a series of merocyanine-type dyes. These dyes exhibit intense blue-light absorption but weak fluorescence. An electron-donating alkylamino group at position C4 is responsible for the solvatochromic behavior of the dyes since the lone electron pair of the nitrogen atom is variably delocalized toward the barbituric ring, which exhibits electron-withdrawing properties. This was elucidated, taking into account the different geometry of the amino group. The intramolecular charge transfer in the molecules is responsible for the relatively high redshift in absorption and fluorescence spectra. Additionally, an increase in solvent polarity moves the absorption and fluorescence to lower energy regions. The observed solvatochromism is discussed in terms of the four-parameter Catalán solvent polarity scale. The differences in the behavior of the dyes were quantified with the aid of time-dependent density functional theory calculations. The obtained results made it possible to find regularities linking the basic spectroscopic properties of the compounds with their chemical structure. This is important in the targeted search for new, practically important dyes.

On-Surface Synthesis of Polyene-Linked Porphyrin Cooligomer.

π-Conjugated molecules are viewed as fundamental components in forthcoming molecular nanoelectronics in which semiconducting functional units are linked to each other via metallic molecular wires. However, it is still challenging to construct such block cooligomers on the surface. Here, we present a synthesis of [18]-polyene-linked Zn-porphyrin cooligomers via a two-step reaction of the alkyl groups on Cu(111) and Cu(110). Nonyl groups (-C9H19) substituted at the 5,15-meso positions of Zn-porphyrin were first transformed to alkenyl groups (-C9H10) by dehydrogenation. Subsequently, homocoupling of the terminal -CH2 groups resulted in the formation of extended [18]-polyene-linked porphyrin cooligomers. The structures of the products at each reaction step were investigated by bond-resolved scanning tunneling microscopy at low temperatures. A combination of angle-resolved photoemission spectroscopy and density functional theory calculations revealed the metallic property of the all trans [18]-polyene linker on Cu(110). This finding may provide an approach to fabricate complex nanocarbon structures on the surface.

Relationships between conformational and vibrational features of tryptophan characteristic Raman markers.

Tryptophan (Trp) residue provides characteristic vibrational markers to the middle wavenumber spectral region of the Raman spectra recorded from peptides and proteins. In this report, we were particularly interested in eight Trp Raman markers, referred to as Wi (i = 1,…,8). All responsible for pronounced Raman lines, these markers originate from indole moiety, a bicyclic conjugated segment involved in the Trp structure. Numerous investigations have previously attempted to relate the variations observed in the spectral features of these markers to the environmental changes of Trp residues. To emphasize the most important points we can mention (i) the variations in the Raman profile of W4 (∼1360 cm-1) and W5 (∼1340 cm-1), frequently observed as a doublet with variable intensity ratio. These two markers were thought to result from a Fermi-resonance effect between certain planar and nonplanar modes; (ii) the changes observed in the wavenumbers and relative intensities of W4, W7 (∼880 cm-1) and W8 (∼760 cm-1) were supposed to be related to the accessibility of Trp to surrounding water molecules; and (iii) the wavenumber fluctuations of W3 (∼1550 cm-1), taken as a Trp side chain orientational marker. However, some ambiguities still exist regarding the interpretation of these markers, needing further clarification. Herein, upon a joint experimental and theoretical analysis based on a multiconformational approach, attention was paid to the relationships between structural and vibrational features of three indole-containing compounds with increasing structural complexity, i.e., skatole (3-methylindole), tryptophan, and tripeptide Gly-Trp-Gly. This study clearly shows that the existing assignments given to certain Trp Raman markers should be reconsidered, especially those based on the Fermi-resonance origin of W4-W5 (∼1360-1340 cm-1) doublet, as well as the purely environmental dependence of W7 and W8 markers.

Sc-Modified C3N4 Nanotubes for High-Capacity Hydrogen Storage: A Theoretical Prediction.

Utilizing hydrogen as a viable substitute for fossil fuels requires the exploration of hydrogen storage materials with high capacity, high quality, and effective reversibility at room temperature. In this study, the stability and capacity for hydrogen storage in the Sc-modified C3N4 nanotube are thoroughly examined through the application of density functional theory (DFT). Our finding indicates that a strong coupling between the Sc-3d orbitals and N-2p orbitals stabilizes the Sc-modified C3N4 nanotube at a high temperature (500 K), and the high migration barrier (5.10 eV) between adjacent Sc atoms prevents the creation of metal clusters. Particularly, it has been found that each Sc-modified C3N4 nanotube is capable of adsorbing up to nine H2 molecules, and the gravimetric hydrogen storage density is calculated to be 7.29 wt%. It reveals an average adsorption energy of -0.20 eV, with an estimated average desorption temperature of 258 K. This shows that a Sc-modified C3N4 nanotube can store hydrogen at low temperatures and harness it at room temperature, which will reduce energy consumption and protect the system from high desorption temperatures. Moreover, charge donation and reverse transfer from the Sc-3d orbital to the H-1s orbital suggest the presence of the Kubas effect between the Sc-modified C3N4 nanotube and H2 molecules. We draw the conclusion that a Sc-modified C3N4 nanotube exhibits exceptional potential as a stable and efficient hydrogen storage substrate.

Ferroheme/Ferriheme Directly Involved in the Synthesis and Decomposition of Hydrazine as an Electron Carrier during Anammox.

Anammox bacteria performed the reaction of NH4+ and NO with hydrazine synthase to produce N2H4, followed by the decomposition of N2H4 with hydrazine dehydrogenase to generate N2. Ferroheme/ferriheme, which serves as the active center of both hydrazine synthase and hydrazine dehydrogenase, is thought to play a crucial role in the synthesis and decomposition of N2H4 during Anammox due to its high redox activity. However, this has yet to be proven and the exact mechanisms by which ferroheme/ferriheme is involved in the Anammox process remain unclear. In this study, abiotic and biological assays confirmed that ferroheme participated in NH4+ and NO reactions to generate N2H4 and ferriheme, and the produced N2H4 reacted with ferriheme to generate N2 and ferroheme. In other words, the ferroheme/ferriheme cycle drove the continuous reaction between NH4+ and NO. Raman, ultraviolet-visible spectroscopy, and X-ray absorption fine structure spectroscopy confirmed that ferroheme/ferriheme is involved in the synthesis and decomposition of N2H4 via the core FeII/FeIII cycle. The mechanism of ferroheme/ferriheme participation in the synthesis and decomposition of N2H4 was proposed by density functional theory calculations. These findings revealed for the first time the heme electron transfer mechanisms, which are of great significance for deepening the understanding of Anammox.

Electron Localization and Mobility in Monolayer Fullerene Networks.

The novel 2D quasi-hexagonal phase of covalently bonded fullerene molecules (qHP C60), the so-called graphullerene, has displayed far superior electron mobilities, if compared to the parent van der Waals three-dimensional crystal (vdW C60). Herein, we present a comparative study of the electronic properties of vdW and qHP C60 using state-of-the-art electronic-structure calculations and a full quantum-mechanical treatment of electron transfer. We show that both materials entail polaronic localization of electrons with similar binding energies (≈0.1 eV) and, therefore, they share the same charge transport via polaron hopping. In fact, we quantitatively reproduce the sizable increment of the electron mobility measured for qHP C60 and identify its origin in the increased electronic coupling between C60 units.

Bis(dimethylpyrazolyl)-aniline-s-triazine derivatives as efficient corrosion inhibitors for C-steel and computational studies.

4,6-Bis(3,5-dimethyl-1H-pyrazol-1-yl)-N-phenyl-1,3,5-triazin-2-amine (PTA-1), N-(4-bromophenyl)-4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,3,5-triazin-2-amine (PTA-2) and 4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-N-(4-methoxyphenyl)-1,3,5-triazin-2-amine (PTA-3) were synthesized and characterized. Their corrosion inhibition of carbon C-steel in 0.25 M H2SO4 was studied by electrochemical impedance. The inhibition efficiency (IE%) of triazine was superior due to the cumulative inhibition of triazine core structure and pyrazole motif. Potentiodynamic polarizations suggested that s-triazine derivatives behave as mixed type inhibitors. The IE% values were 96.5% and 93.4% at 120 ppm for inhibitor PTA-2 and PTA-3 bearing -Br and -OCH3 groups on aniline, respectively. While PTA-1 without an electron donating group showed only 79.0% inhibition at 175 ppm. The adsorption of triazine derivatives followed Langmuir and Frumkin models. The values of adsorption equilibrium constant K°ads and free energy change ΔG°ads revealed that adsorption of inhibitor onto steel surface was favoured. A corrosion inhibition mechanism was proposed suggesting the presence of physical and chemical interactions. Density functional theory computational investigation corroborated nicely with the experimental results. Monte Carlo simulation revealed that the energy associated with the metal/adsorbate arrangement dE ads/dN i, for both forms of PTA-2 and PTA-3 with electron donating groups (-439.73 and -436.62 kcal mol-1) is higher than that of PTA-1 molecule (-428.73 kcal mol-1). This aligned with experimental inhibition efficiency results.

Theoretical calculations and experimental verification of carbon dioxide reduction electrocatalyzed by metalloporphyrin.

Metal-functionalized porphyrin-like graphene structures are promising electrocatalysts for carbon dioxide reduction reaction (CO2RR) as their metal centers can modulate activity. Yet, the role of metal center of metalloporphyrins (MTPPs) in CO2 reaction activity is still lacking deep understanding. Here, CO2RR mechanism on MTPPs with five different metal centers (M = Fe, Co, Cu, Zn and Ni) are examined by first-principles calculations. The *COOH formation is the rate determined step on the five MTPP structures, and the CoTPP exhibits the best CO2RR activity while ZnTPP and NiTPP are the worst, which is also verified by our experiment. The CO2RR activity is controlled by adsorption states of intermediates (*CO, *COOH), i.e., chemisorption (e.g., on CoTPP) and physisorption (on ZnTPP and NiTPP) of intermediates will lead to good and poor activity, respectively. The deeper the d-band center of the porphyrin ring complexed metal atom, the weaker bonding of MTPP with CO and COOH. Theoretical calculations and experimental results indicate that MTPPs with Co and Fe centers lead to a reduction in the energy barriers for the two uphill reaction steps in the electrocatalytic CO2 reduction process, thereby enhancing CO2 reduction electrocatalytic activity. Faradaic efficiency of CO is correlated with the reaction energy barrier of the first proton-coupled electron reduction process, displaying a strong linear correlation. This work provides a fundamental understanding of MTPPs used as electrocatalysts for CO2RR.

Alloying Driven Antiferromagnetic Skyrmions on NiPS3 Monolayer: A First-Principles Calculation.

Topological magnetic states are promising information carriers for ultrahigh-density and high-efficiency magnetic storage. Recent advances in two-dimensional (2D) magnets provide powerful platforms for stabilizing various nanometer-size topological spin textures within a wide range of magnetic field and temperature. However, non-centrosymmetric 2D magnets with broken inversion symmetry are scarce in nature, making direct observations of the chiral spin structure difficult, especially for antiferromagnetic (AFM) skyrmions. In this work, it is theoretically predicted that intrinsic AFM skyrmions can be easily triggered in XY-type honeycomb magnet NiPS3 monolayer by alloying of Cr atoms, due to the presence of a sizable Dzyaloshinskii-Moriya interaction. More interestingly, the diameter of the AFM skyrmions in Ni3/4Cr1/4PS3 decreases from 12 to 4.4 nm as the external magnetic field increases and the skyrmion phases remain stable up to an external magnetic field of 4 T. These results highlight an effective strategy to generate and modulate the topological spin texture in 2D magnets by alloying with magnetic element.

Mechanistic studies to understand peak tailing due to sulfinic acid- and carboxylic acid-silanophilic interactions in reversed-phase liquid chromatography.

Silanophilic interactions are a primary contributor to peak tailing of acidic pharmaceutical compounds, thus a thorough understanding is especially important for reversed-phase liquid chromatography (RPLC) method development. Herein, a sulfinic acid compound that exhibited severe peak tailing in RPLC with acidic mobile phases was carefully studied. Results indicated that the neutral protonated form of the sulfinic acid is involved in the strong interaction that leads to peak tailing, but that tailing can be mitigated with a blocking effect achieved through use of acetic acid modifier in the mobile phase. Peak tailing was also observed with other structurally-similar sulfinic acids and carboxylic acids but was, in general, less severe with the latter. The Hydrophobic Subtraction Model (HSM) was applied to six commercial C18 columns that exhibited different tailing behaviors for the sulfinic acid compound in attempts to identify key sites of interaction within the stationary phase. A combination of heated acid column wash experiments and density functional theory (DFT) calculations indicate that the differential interactions of the acids with vicinal silanol pairs in the stationary phase play a major role in peak tailing.

Distance-Dependent Evolution of Electronic States in Kagome-Honeycomb Lateral Heterostructures in FeSn.

In this work, we demonstrate the formation and electronic influence of lateral heterointerfaces in FeSn containing Kagome and honeycomb layers. Lateral heterostructures offer spatially resolved property control, enabling the integration of dissimilar materials and promoting phenomena not typically observed in vertical heterostructures. Using the molecular beam epitaxy technique, we achieve a controllable synthesis of lateral heterostructures in the Kagome metal FeSn. With scanning tunneling microscopy/spectroscopy in conjunction with first-principles calculations, we provide a comprehensive understanding of the bonding motif connecting the Fe3Sn-terminated Kagome and Sn2-terminated honeycomb surfaces. More importantly, we reveal a distance-dependent evolution of the electronic states in the vicinity of the heterointerfaces. This evolution is significantly influenced by the orbital character of the flat bands. Our findings suggest an approach to modulate the electronic properties of the Kagome lattice, which should be beneficial for the development of future quantum devices.