Density Functional Theoretical Calculations Research Articles

Cover Feature: Synthesis and Computational Investigation of Antioxidants Prepared by Oxidative Depolymerization of Lignin and Aldol Condensation of Aromatic Aldehydes (ChemSusChem 12/2023)

The Cover Feature shows novel antioxidants synthesized by oxidative depolymerization of lignin to form aromatic aldehydes followed by aldol condensation with methyl ethyl ketone (MEK). Aldol condensation was found to greatly improve the antioxidation ability of lignin depolymerized products. p-Hydroxybenzaldehyde, vanillin, and syringaldehyde as representative aromatic aldehydes were further employed for aldol condensation with MEK, resulting in successful synthesis of new antioxidants. The newly synthesized antioxidants could be used as a green additive of biodiesel to increase its oxidation stability. Density functional theoretical calculations confirmed that electron-donating groups such as methoxyl and conjugated side chains could effectively improve the antioxidation ability of the obtained antioxidants. More information can be found in the Research Article by D. Gao et al.

Direct observation on argon tagging nitrobenzene radical anion in gas phase: Infrared photodissociation spectroscopy and theoretical calculation.

The infrared photodissociation spectroscopy was applied to characterize nitrobenzene radical anion (NB-). NB- tagged by argon [NB(Ar)-] was prepared by a mixture of nitrobenzene/Ar through a supersonic ion source and then selected by a time-of-flight mass spectrometer. Eight strong peaks observed at 977.9, 999.6, 1059.8, 1275.7, 1309.7, 1339.7, 1367.6 and 1581.7cm-1 in the fingerprint region were assigned to NB(Ar)-, corresponding to CC bending, CC stretching, CC bending+symmetric O-N stretching vibration, antisymmetric O-N and CC stretching vibration, antisymmetric O-N stretching and CH rocking vibration, CC stretching+antisymmetric O-N stretching vibration, C-N stretching vibration, and symmetric CC stretching vibration. Most interestingly, the distinguishable CH stretching vibrations were observed at 3006.5, 3048.6 and 3084.5cm-1 absorptions. Combined with density functional theoretical (DFT) calculation, five tagging argon NB- isomers were optimized and analyzed with no imaginary frequency. The results indicated that most bond lengths in NB- become longer than those of neutral NB, except for the C1-C2/C4-C5 bonds, which are only slightly shorter than those of neutral NB, and the C-N bond, which is 0.085 A shorter in the anion. The NB- tagged by argon located on the nitro group had no change on bond parameters with Ar-tagging or not theoretically. Natural population analysis (NPA) show that the negative natural charges are mainly distributed on both oxygen atoms. And the one electron resonates between the nitro group and benzene ring. N-O bonds in NB- become much more polar than those of the neutral NB. This paper proved the usefulness to characterize NB(Ar)- and further explore the structures of NBn- (n>1) clusters by infrared photodissociation spectroscopy combining with the time-of-flight mass spectrometer.

B atom dopant-manipulate electronic structure of CuIn nanoalloy delivering wide potential activity over electrochemical CO2RR

The accuracy and efficiency tuning the local electronic structure of catalyst active sites are pre-requisites for achieving high selectivity CO2 reduction reaction on a wide potential window, whereas remain a great challenge. Here, a B-doped CuIn alloy catalyst with tunable electronic structure for the highly effective electrochemical conversion of CO2 to CO has been exploited. The obtained B-doped CuIn alloy performs an optimal CO Faraday efficiency of 99% at –0.6 V (vs. the reversible hydrogen electrode) and particularly keeps outstanding CO Faraday efficiency (> 90%) over a wide cathodic electrochemical window (400 mV). Density functional theory theoretical calculation manifests that the enhanced performance is primarily ascribed to the electron-capturing ability of high valence state B atom, which optimizes the local electronic structure of adjacent metal active sites and adjusts the binding energy between catalyst and intermediates. A foundation of designing advanced electrochemical CO2 reduction reaction catalysts can be served by the insights gained though this research.

Noncovalent Modulation of Chemoselectivity in the Gas Phase Leads to a Switchover in Reaction Type from Heterolytic to Homolytic to Electrocyclic Cleavage.

Inthe gas phase, thermal activation of supramolecular assemblies such as host-guest complexes leads commonly to noncovalent dissociation into the individual components. Chemical reactions, for example of encapsulated guest molecules, are only found in exceptional cases. As observed by mass spectrometry, when 1-amino-methyl-2,3-diazabicyclo[2.2.2]oct-2-ene (DBOA) is complexed by the macrocycleb-cyclodextrin, its protonated complex undergoes collision-induced dissociation into its components, the conventional reaction pathway. Inside the macrocyclic cavity of cucurbit[7]uril (CB7), a competitive chemical reaction of monoprotonated DBOA takes place upon thermal activation, namely a stepwise homolytic covalent bond cleavage with the elimination of N2, while the doubly protonated CB7•DBOA complex undergoes an inner-phase elimination of ethylene, a concerted, electrocyclic ring-opening reaction. These chemical reaction pathways stand in contrast to the gas-phase chemistry of uncomplexed monoprotonated DBOA, for which an elimination of NH3predominates upon collision-induced activation, as a heterolytic bond cleavage reaction. The combined results, which can be rationalized in terms of organic-chemical reaction mechanisms and density-function theoretical calculations, demonstrate that chemical reactions in the gas phase can be steered chemoselectively through noncovalent interactions.

Bio-Inspired Electrochemical Detection of Nitric Oxide Promoted by Coordinating the Histamine-Iron Phthalocyanine Catalytic Center on Microelectrode.

Biomimetic structures to fabricate bioelectronic interfaces that allow sensors to electrically communicate with electrodes have potential applications in the development of biosensors. Herein, inspired by the structure feature of nitric oxide (NO) sensory protein, we constructed a biomimetically catalytic center, the histamine coordinated iron phthalocyanine (FePc), for efficient and sensitive detection of NO. In specific, NO is recognized by axial tethered FePc, and the oxidative signal of NO on FePc is converted into output signal through electrocatalytic oxidation. Based on the fabricated catalytic structure on the carbon fiber electrode, on one hand, the macrocyclic π system of FePc enabled a rapid redox process, which facilitates electron transfer, thereby greatly improving sensitivity. On the other hand, by coordination with histamine on the electrode surface, FePc can enhance the electrochemical oxidation activity toward NO and promote catalytic detection, which have been revealed by electrochemical characterizations and density functional theory theoretical calculations. The designed electrochemical microsensor exhibits a low limit of detection (0.03 nM) and shows a wide detection range (0.1 nM-2 μM). In addition, the electrochemical microsensor has been successfully used for real-time monitoring of NO release by live cells. So, this work shows a new strategy for the design of bio-inspired electrochemical microsensors that may provide a potential analytical tool for tracing biological signal molecules with enzyme-free biomimetically catalytic centers.

Tri-functional Ru-RuO2/Mn-MoO2 composite: A high efficient electrocatalyst for overall water splitting and rechargeable Zn–air batteries

Preparation of highly efficient multi-functional electrocatalyst is extremely useful for application but quite challengeable. Herein, a new tri-functional Ru-RuO2/Mn-doped MoO2 (RRMM) electrocatalyst was successfully prepared through a facile solid phase reaction strategy. RRMM catalyst exhibits the small overpotential of 15 and 260 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at a current density of 10 mA cm−2, respectively. A low cell voltage of 1.53 V is required to achieve a current density of 10 mA cm−2 for overall water splitting. Meanwhile, a half-wave potential of 0.83 V was needed for oxygen reduction reaction (ORR) and assembled Zn–air battery exhibits an excellent stability. Density functional theoretical calculations also revealed that Ru-RuO2 active units facilitated reaction kinetics of HER and OER, while the synergistic effect of Ru and Mn-doped MoO2 endowed RRMM catalyst with excellent ORR activity.

Accurate Layer Spacing Matching of Polyoxometalate (POM) Anion‐based Ionic Liquids (ILs) to Promote PET Alcoholysis

AbstractMatching the active site of the catalyst with the carbonyl reactive site of PET at the nanoscale and achieve precise shearing of the PET reactive site at the molecular level by accurately modulating the catalyst layer spacing is particularly challenging. Herein, a new design strategy for green catalysts is proposed to synthesize a novel class of Polyoxometalate (POM) anion‐based ILs (POM‐ILs) [X]n[WZn3(H2O)2(ZnW9O34)2] (X=PyPs, Py, MIMPs, TEAPs, n=3, 6, 9, 12) with high thermally stable and adjustable layer spacing (1.00–1.63 nm). By adjusting the ratio of organic cations to match the spacing (1.34 nm) between the active sites of the catalyst with the spacing (1.32 nm) of the carbonyl functional groups on both sides of the PET benzene ring, the long PET chains were precisely sheared and rapidly degraded to bis(hydroxyethyl) terephthalate (BHET) in short time with the synergistic catalytic effect of anions and cations. Under the optimal conditions, the catalyst dosage was only 0.8 % of PET mass, and it could degrade 100 % in 30 min with BHET yield up to 85.35 %, and the yield of BHET was still greater than 85 % after 5 cycles. In addition, a possible mechanism of synergistic catalytic PET alcoholysis was proposed by density functional theoretical calculation. Moreover, the strategy of promoting PET alcoholysis by accurately modulating the spacing of the catalytic active site has not been reported.

Experimental and computational study on the spectroscopic and colorimetric copper sensing behaviour of three ketimine derivatives

Three imine based colorimetric copper sensors were successfully synthesized and their copper sensing behaviours characterized via absorption spectroscopy and rationalized by density functional theoretical (DFT) calculations. All three compounds interact strongly with copper in non-aqueous and semi- aqueous media, as indicated by the exergonic nature of this process: ΔGbinding = ∼ -28 kJ mol−1, which leads to a visible colour change; a process controlled by entropic effects in combination with the relative hardness of the binding sites. These compounds allow selective detection of copper at concentrations as low as 0.16 ppm with linear ranges of 1–5 ppm and quantification limits as low as 0.52 ppm. Whereas, only zinc leads to reduced accuracy for 2-[1-(2-hydroxyphenyl)ethylideneamino]phenol, at equimolar levels, for the other derivatives, hard-soft interactions allow significant interference from various metals, present at such a concentration. Overall, these compounds represent a viable starting point for the development of cheap colorimetric copper sensors.

Synthesis and computational investigation of novel antioxidants prepared by oxidative depolymerization of lignin and aldol condensation of aromatic aldehydes.

Novel antioxidants were synthesized by CuSO4 catalyzed oxidative depolymerization of lignin to form aromatic aldehydes followed by aldol condensation with methyl ethyl ketone (MEK). Aldol condensation was found to greatly improve the antioxidation ability of lignin depolymerized products. Three lignin monomeric aromatic aldehydes, i.e. p-hydroxybenzaldehyde, vanillin, and syringaldehyde were further employed for aldol condensation with MEK, resulting in successful synthesis of new antioxidants, 1-(4-hydroxyphenyl)pent-1-en-3-one (HPPEO), 1-(4-hydroxy-3-methoxyphenyl)pent-1-en-3-one (HMPPEO) and 1-(4-hydroxy-3,5-dimethoxyphenyl)pent-1-en-3-one (HDMPPEO), respectively. Kinetic modeling illustrated that p-hydroxybenzaldehyde had the largest rate to react with MEK, followed by vanillin and then syringaldehyde, which was probably affected by the presence of methoxyl groups. Syringaldehyde derived product (HDMPPEO) displayed the best antioxidation ability. As revealed by density functional theoretical calculation, electron-donating group such as methoxyl group and conjugated side chain could effectively improve the antioxidation ability. Hydrogen atom transfer (HAT) mechanism was prone to occur in non-polar solvents while the sequential proton loss electron transfer (SPLET) mechanism was favored in polar solvents. This work thus can inspire new pathways for valorization of lignin to produce high value-added products.

Comparative study on twelve kinds of electron donors for organic functional materials

The development and comparison of different kinds of donors showed very important role in the field of organic functional materials. A series of nonlinear optical chromophores 1–12 were developed based on twelve different types of electron donors, with the same isophorone based bridge and TCF acceptor. The donors studied include Ethyl methylaniline, tetrahydroquinoline, Ethoxykowloon aniline, triphenylamine, thiophen-2-amine derivatives, bis(alkyl)aniline derivatives and poly heteroatom aniline. Thermal stability analysis, optical properties, Density functional theoretical calculation (DFT) and electro-optical coefficient test of these chromophores was systematically studied to display the effect of different donors on the properties of Chromophores. The results show that the introduction of one or more heteroatoms can effectively improve the electron donating ability of the donor, so as to improve the first hyperpolarizability of the chromophore. The doped film containing the 25 wt% chromophore 1–12 showed electro-optic coefficients from 54 to 163 p.m./V, respectively.

ZnxZrO2+x-Based Photocatalyst with Dual Active Sites for Tunable Syngas Production from CO2 Photoreduction

Photocatalytic reduction of CO2 in H2O to CO and H2 for syngas production is an attractive option to solve global warming and generate a feedstock for the Fischer–Tropsch process. The syngas generated from CO2 photoreduction with a precise and controllable ratio of H2/CO remains a major challenge to date. In this work, CdS-sensitized nanoscale ZnxZrO2+x solid solutions with dual active sites were synthesized as photocatalysts for tunable syngas H2 and CO production from CO2 photoreduction. The staggered band energy alignments, electron paramagnetic resonance results, and the site of palladium/gold nanoparticles by photodeposition indicate that the charge transfer in the CdS/ZnxZrO2+x heterojunction mainly follows the conventional type II mechanism. Density functional theoretical calculation results reveal that Zn and Zr sites on ZnxZrO2+x are favorable for the adsorption of H2O and CO2 molecules and generation of H2 and CO, respectively. The H2/CO ratio can be controlled in the range from 0.9 to 25.0 by adjusting the content of Zn in ZnxZrO2+x. Moreover, syngas production can be further improved by the modification of Pd nanoparticles. For the first time, this work proposes a strategy to construct a photocatalyst with dual active sites for effectively controlling the H2/CO ratio in syngas synthesis through a fundamental understanding of adsorption and catalytic reaction sites in both H2 evolution and CO2 reduction reactions.

Weak antilocalization and topological edge states in PdSn4

Here, we report a successful synthesis of single crystals of a topological semimetal (TSM) candidate, PdSn4, using a self-flux route. The synthesized crystal is well characterized through x-ray diffraction (XRD), field emission scanning electron microscopy, and x-ray photoelectron spectroscopy. A detailed Rietveld analysis of the powder XRD pattern of PdSn4 confirmed the same to crystallize in an Aea2 space group instead of reported Ccce. A large magnetoresistance (MR) along with Shubnikov–de Haas (SdH) oscillations have been observed in magneto-transport measurements at 2 K. The presence of weak antilocalization (WAL) effect in the synthesized PdSn4 crystal is confirmed and analyzed using Hikami Larkin Nagaoka formalism, being applied on magnetoconductivity of the same at a low magnetic field. An extended Kohler's rule is implemented on MR data to determine the role of scattering processes and temperature-dependent carrier density on the transport phenomenon in PdSn4. Furthermore, the non-trivial band topology and the presence of edge states are shown through density functional theory-based theoretical calculations. All calculations are performed considering the Aea2 space group symmetry. The calculated Z2 invariants (0; 0 1 0) suggest the presence of weak topological insulating properties in PdSn4. A clear evidence of topological edge states at Γ point is visible in calculated edge states spectra. This is the first report on PdSn4, showing the presence of SdH oscillation in magneto-transport measurements. Also, the presence of a weak insulating phase in PdSn4 is described for the first time on the basis of calculated Z2 invariants.

Construction of Ru/WO3 with hetero-interface structure for efficient hydrogen evolution reaction

Water electrolysis is considered as one most promising technique for hydrogen production. The high efficiency electrocatalyst is the key to accelerating the sluggish kinetics of the hydrogen evolution reaction (HER) in alkaline media. In this work, an efficient HER electrocatalyst with hetero-interfacial metal–metal oxide structure was constructed through a redox solid phase reaction (SPR) strategy. During the annealing process under Ar atmosphere, RuO2 and WS2 in RuO2/WS2 precursor were converted to Ru nanoparticles (NPs) and WO3 in situ, where tiny Ru NPs and oxygen vacancies were uniformly distributed onto the newly formed WO3 nanosheets. Different characterization techniques were adopted to confirm the successful formation of Ru/WO3 electrocatalyst (RWOC). The optimized RWOC sample annealed at 400 °C exhibited the low overpotential value of 13 mV at a current density of 10 mA cm−2 and strong durability under the alkaline condition. Density functional theoretical calculations further revealed that the promoted adsorption/desorption rate of reaction intermediates and the accelerated kinetics of HER process were deduced to the synergistic effect between Ru and WO3 in electrocatalyst. This work provides a feasible method to fabricate highly efficient HER electrocatalysts.

Engineering carbon semi-tubes supported platinum catalyst for efficient oxygen reduction electrocatalysis

Innovation of catalyst structure is extremely important to develop the high-performance electrocatalysts for oxygen-reduction reaction (ORR). Herein, nitrogen-doped carbon semi-tube (N-CST) is used as a functional support for stabilizing the microwave-reduced Pt nanoparticles with an average size of ∼2.8nm to synthesize the semi-tubular Pt/N-CST catalyst. The contribution of interfacial Pt-N bond between N-CST support and Pt nanoparticles with electrons transfer from N-CST support to Pt nanoparticles is found by electron paramagnetic resonance (EPR) and X-ray absorption fine structure (XAFS) spectroscopy. This bridged Pt-N coordination can simultaneously help ORR electrocatalysis and promote electrochemical stability. As a result, the innovative Pt/N-CST catalyst exhibits excellent catalytic performance, realizing ORR activity and electrochemical stability superior to the commercial Pt/C catalyst. Furthermore, density functional theoretical (DFT) calculations suggest that the interfacial Pt-N-C site with unique affinity of O∗+ OH∗ can provide new active routes for the enhanced electrocatalytic ORR capacity.

Synthesis of ESIPT fluorophores with two intramolecular H-bonding functionalities: Reversible mechanofluorochromism and conformation controlled solid state fluorescence efficiency

We have synthesized two new ESIPT fluorophores (1-((E)-((E)-((2-hydroxyphenyl)(phenyl)methylene)hydrazono)methyl) naphthalen-2-ol (Naph-2-OH) and 5-(diphenylamino)-2-((E)-((E)-((2-hydroxyphenyl)(phenyl) methylene)hydrazono)methyl) phenol (TPA-2-OH)) with two unsymmetrical intramolecular H-bonding functionalities and investigated the solid-state structural assembly and fluorescence properties. The crystal structure analysis confirmed the formation of strong intramolecular H-bonding and twisted molecular conformation. The nonplanar twisted molecular conformation produced well separated molecules in the crystal lattice that lead to strongly enhanced emission ((λmax = 538 nm, Φf = 5.2% (Naph-2-OH), λmax = 562 nm, Φf = 13.4% (TPA-2-OH)). Density functional theoretical (DFT) calculation supported the fluorescence tuning and intramolecular charge transfer (ICT) from TPA donor to imine acceptor. Both Naph-2-OH and TPA-2-OH showed mechanical crushing and heating induced reversible fluorescence switching due to the reversible phase transformation between crystalline and amorphous state.

Fluorenone Appended Colorimetric Sensor for Cascade Detection of Fluoride and Calcium Gluconate with Applications in Solid State and Logic Gate Systems

AbstractA novel fluorenone derived Schiff base chemosensor (1) has been synthesized as a colorimetric sensor for fluoride (F−) ions in CH3CN and characterized by various analytical techniques. The chemosensor 1 perceived high selectivity for F− ion detection in the presence of other anions along with naked eye color change from yellow to orange‐red with quantitative detection limit of 900 nM. The UV‐vis changes, density functional theoretical (DFT) calculations and 1H NMR titration studies pointed to F− ion induced deprotonation of −OH of sensor 1 that has been proposed to be responsible for the observed absorption as well as color changes. The sensor 1 has also been efficiently applied for the solid state concentration dependent naked eye detection of F− ions in the form of filter paper strips and smartphone applications. The in‐situ generated 1‐F− complex was further utilized for cascade recognition of calcium gluconate (CG). The reversible and reproducible changes produced by the addition of F− ions and CG enabled 1 to be used as “INHIBIT” molecular logic system and “SET/RESET” memorized device at the molecular level.

Pressure tuning of structure, magnetic frustration, and carrier conduction in the Kitaev spin liquid candidate Cu2IrO3

The layered honeycomb lattice iridate Cu$_2$IrO$_3$ is the closest realization of the Kitaev quantum spin liquid, primarily due to the enhanced interlayer separation and nearly ideal honeycomb lattice. We report pressure-induced structural evolution of Cu$_2$IrO$_3$ by powder x-ray diffraction (PXRD) up to $\sim$17 GPa and Raman scattering measurements up to $\sim$25 GPa. A structural phase transition (monoclinic $C2/c \: \rightarrow$ triclinic $P\bar{1}$) is observed with a broad mixed phase pressure range ($\sim$4 to 15 GPa). The triclinic phase consists of heavily distorted honeycomb lattice with Ir-Ir dimer formation and a collapsed interlayer separation. In the stability range of the low-pressure monoclinic phase, structural evolution maintains the Kitaev configuration up to 4 GPa. This is supported by the observed enhanced magnetic frustration in dc susceptibility without emergence of any magnetic ordering and an enhanced dynamic Raman susceptibility. High-pressure resistance measurements up to 25 GPa in the temperature range 1.4--300 K show resilient non-metallic $R$($T$) behaviour with significantly reduced resistivity in the high-pressure phase. The Mott 3D variable-range-hopping conduction with much reduced characteristic energy scale $T_0$ suggests that the high-pressure phase is at the boundary of localized-itinerant crossover. Using first-principles density functional theoretical (DFT) calculations, we find that at ambient pressure $\rm Cu_2IrO_3$ exists in monoclinic $P2_1/c$ phase which is energetically lower than $C2/c$ phase (both the structures are consistent with experimental XRD pattern). DFT reveals structural transition from $P2_1/c$ to $P\bar{1}$ structure at 7 GPa (involving dimerization of Ir-Ir bonds) in agreement with experimentally observed transition pressure.

High-Performance Polyimides Derived from Biomass: Design, Synthesis, and Properties

The development of sustainable polyimides (PIs) from abundant renewable biogenic feedstocks has been limited by the bio-based content and the lack of mechanical and thermal properties. This study synthesized a series of daidzein-based PIs with a high bio-based content of up to 53%, which was significantly higher than the reported bio-based content (approximately 40%). The mechanical and thermal stability of the obtained polymer is comparable with that of commercial PIs, with the tensile strength of 148.6 MPa and the glass transition temperature (Tg) of 318.2 °C. Additionally, the daidzein-based PIs showed excellent fluorescence characteristics with a maximum fluorescence efficiency of 45.18 ns and an absolute fluorescence quantum yield of 14.1%. Such a performance combination has not been reported in bio-based PIs, even petrochemical PIs. Interestingly, the integration of experiments and density functional theoretical calculations revealed an effective intermolecular and intramolecular conjugation and the inhibition effect of intramolecular charge transfer by “enone and ether bonds” in daidzein-derived PIs. This work provides a possible route for the design and synthesis of multifunctional PIs with high bio-based content.

A dual-functional chemosensor based on acylhydrazone derivative for rapid detection of Zn(II) and Mg(II): Spectral properties, recognition mechanism and application studies

In this work, an acylhydrazone derivative (QN62) was developed via the one-step condensation of 6-hydroxy-2-naphthoic hydrazide with quinoline-8-carboxaldehyde. The structure of the QN62 compound was characterized by 1H NMR, 13C NMR, HR-MS (ESI), and X-ray crystallography. As a dual-functional turn-on fluorescence chemosensor, QN62 exhibited rapid recognition for Zn2+ in DMSO-H2O (4:1, v/v) and Mg2+ in ethanol-H2O (9:1, v/v). The enhancement in fluorescence detection was associated with the coordination reaction between QN62 and the target ions, which promoted intramolecular charge transfer and prevented the CN isomerization process. Simultaneously, a rapid color change from colorless to yellowish-green or yellow under UV light (365 nm) was easily visible to the naked eye. Under optimal conditions, the limit of detection and limit of quantification were 32.3 nM and 97.8 nM for Zn2+ and 16.1 nM and 48.9 nM for Mg2+, respectively. The recognition mechanism was reasonably speculated based on analysis of the Job’s plot, HR-MS, 1H NMR, and density functional theoretical calculations. Utilizing silica-gel plates fabricated from the QN62 chemosensor, the visual and rapid identification of Zn2+ and Mg2+ was successfully achieved, which could provide a convenient approach for on-site detection in environmental fields. The QN62 chemosensor could also quantify trace amounts of Zn2+ and Mg2+ in water samples. Furthermore, the cell imaging experiments indicated that QN62 could effectively sense intracellular Zn2+ and Mg2+, providing potential applications in biological systems.

Defective Bi2S3 Anchored on CuS/C as an Ultrafast and Long-Life Anode for Sodium-Ion Storage.

Due to the high electrical conductivity and abundant redox active sites, bimetal sulfides are highly competitive anode materials for sodium storage with long-life and high-rate. Herein, a heterostructured metal sulfide (Bi2S3-CuS) with a carbon-based support is prepared by calcination and ion exchange methods. The synergistic effects of the heterostructure and defective structure provide facile diffusion channels, fast Na+ migration, and plentiful active sites for Na+, which reflect in the impressive electrochemical performance with a high reversible capacity of 592.2 mA h g-1 after 1000 cycles at 8 A g-1. Furthermore, the Na-ion full batteries exhibit an ultra-long cycling performance with a value of 216 mA h g-1 after 4000 cycles at 10 A g-1. Interestingly, the defective structure of Bi2S3 remains after cycling. Kinetic analyses and density functional theoretical calculations clarified that the heterointerfacial structure, especially on the interface containing sulfur defects in Bi2S3 of Bi2S3-CuS, could induce feasible ion adsorption and promote ion transfer, which lays the foundation for achieving ultrafast sodiation kinetics.