Internal Charge Transfer Research Articles

Controllable magnetic anisotropy in two-dimensional 1T-CrTe2 with electrides sublayer

Exploring the controlled magnetic anisotropy energy (MAE) in two-dimensional (2D) ferromagnets is an essential step towards the emergent magnetic tunnel junctions (MTJs) with robust storage stability and low-power consumption. In addition to the transitional charge doping method, we propose that stacking 2D ferromagnet 1T-CrTe2 with electrides substrate can achieve not only the high interfacial charge transfer up to 5.24×1014 cm−2 and but also efficient modification of magnetic behaviors via interfacial engineering. Employing first-principles calculations, we show that the 1T-CrTe2/Ca2N(Y2C) heterostructures exhibit a significant reduction in MAE with a spin reorientation. Notably, the synergistic effect of internal charge transfer, external strain and charge doping shows a significant influence on the magnetic behaviors of the bilayer structures, enabling an efficient modulating of their MAE with distinct dependences. We elucidate that the underlying mechanism is the synergistic effect induced alteration of the spin-polarized px and py states on the Te atom located at the interfaces, which in turn changes the competitive spin-orbit coupling (SOC) contributions to the MAE. These findings provide a practical path toward the controllable MAE in 2D ferromagnets, and make the proposed heterostructures promising candidates for emergent spintronic devices.

Study of electrochemical behavior of rGO and Metal-Organic Framework nanocomposite electrodes for supercapacitive applications

Abstract This research studied the electrochemical performance of reduced Graphene Oxide (rGO) and a nanocomposite comprising rGO and Metal-Organic Framework-5 (MOF-5) for supercapacitor applications. The nanocomposite, synthesized through a solvothermal method, aimed to capitalize on the synergistic effects of combining rGO with MOF-5 under normal laboratory conditions without utilizing autoclave. By adjusting the concentration of the oxidizing agent, the oxidation degree of rGO was effectively regulated, thereby influencing its structural properties. Utilizing the optimized rGO, electrodes were fabricated for both rGO and MOF5-rGO configurations. Electrochemical studies were carried out using a three-electrode (3E) system with a 6M KOH electrolyte. The MOF-5, reduced graphene oxide (rGO), and MOF5-rGO nanocomposite samples were characterized using X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) to determine their chemical composition and structural information. The Electrochemical Impedance Spectroscopy (EIS) spectra show low internal resistance (Rs) and charge transfer resistance (Rct), indicating higher conductivity of rGO and nanocomposite. The rGO electrode in the 3E system showed a specific capacitance of 65 Fg-1 whereas MOF5-rGO displayed 73 Fg-1 at a current density of 1.2 Ag-1. MOF5-rGO nanocomposite demonstrates better capacitor retention (96%) compared to rGO (90%) at 5A/g. These results indicate that the MOF5-rGO sample is a promising electrode for supercapacitor application.

The effect of Zn2+ on the positive electrolyte for all-vanadium redox flow battery

In this work, the effects of Zn2+ on the electrochemical activity of positive electrolyte were researched by cyclic voltammetry(CV), AC impedance. The results of CV showed that the positive electrolyte containing 2 wt% Zn2+ as additive had the best electrochemical activity. Compared with the electrolyte without any additive, the electrolyte with 2 wt% Zn2+ obviously enhanced electrochemical activity and reversibility of Farady reaction. In addition, the kinetic study of the mass transfer process indicated that the diffusion coefficient obviously increased. Besides, the results of electrochemical impedance spectroscopy implied that the internal charge transfer resistance of the electrolyte electrochemical system containing Zn2+ as an additive was significantly reduced. This indicated that the charge transfer was significantly accelerated, which was beneficial to the improvement of the electrochemical activity. Moreover, the study of the electrolyte stability showed that the electrolyte containing Zn2+ had superior stability yet after 30 cycles’ scanning.

Aminophenylboronic acid-modified nitrogen-doped graphene quantum dots and their applications in lysine sensing based on interplaying fluorescent mechanisms.

Using nitrogen-doped graphene quantum dots (N-GQDs) and 3-aminophenylboronic acid (APBA), a novel fluorescence nanosensorwas developed. This nanosensor exhibits high selectivity and sensitivity for lysine detection. Its sensing mechanism involves the suppression of electron transfer from APBA to the N-GQDs unit, thereby inhibiting photoinduced electron transfer and initiating internal charge transfer. At an optimal pH of 7, the protonated α-amine and ε-amine groups of lysine interact with the amide and boronic acid moieties, respectively. This interaction results in a redshift of fluorescence, substantially enhancing the response signal. A linear response was observed within a concentration range 0.40-3.01μM, with the detection limit being 0.005μM. A similar linear range was also achieved for the determination of lysine in human serum. Density functional theory calculations correlating molecular orbits and geometries support UV-vis and fluorescence findings. Additionally, the nanosensor wassuccessfully applied to detect lysine in living cells and real samples, including milk and honey. For practical application, we construct a lysine-specific sensing platform using a commercial chip (TCS34725) that collects red, blue, and green signals, thereby facilitating the convenient use of the nanosensor. Overall, this study offers new perspectives on the development and application of fluorescent nanosensors for detecting individual amino acids.

A flexible solid-state asymmetric supercapacitor device comprising cobalt hydroxide and biomass-derived porous carbon.

Development in the field of alternative and renewable energy sources is becoming necessary considering the current energy demands of the growing technologies. The main challenge associated with the produced energy is to store it for future use, such that it can be used when needed. Supercapacitors are among the electrochemical energy storage systems that provides higher power density, faster charging-discharging, high specific capacitance (C S), and long cycling life. Herein, the fabrication of a flexible solid-state asymmetric supercapacitor (ASC) device is reported, where Co(OH)2 hollow spheres and biomass-derived porous carbon (PC) are the cathode and anode, respectively. Co(OH)2 is a highly redox active material, whereas PC is an electric double-layer capacitive (EDLC) material. In this device, aqueous KOH solution (electrolyte) encapsulated in PVA gel (separator) was used to bind the electrodes. This Co(OH)2//PC ASC device exhibited a high C S of 260 F g-1 (at 2 A g-1). It retained ∼91% of the initial C S value (at 6 A g-1) till ∼5000 cycles. Electrochemical impedance spectroscopy (EIS) study confirmed low internal resistance (0.95 Ω) and charge transfer resistance (1.41 Ω) values of Co(OH)2//PC. These results indicate that the high electron transfer process in the electrode-electrolyte interface during the electrochemical reaction, which is responsible for the excellent performance of this ASC device. The high-performance Co(OH)2//PC ASC device exhibited an energy density of 76.7 W h kg-1 at a power density of 1416.9 W kg-1. To demonstrate its practical use, LED lights were illuminated using this Co(OH)2//PC ASC device.

Boosting the lattice oxygen reactivity of perovskite electrocatalyst via less Ru substitution

The successful deployment of efficient oxygen evolution reaction (OER) electrocatalysts is highly essential for multiple clean-energy-related conversion technologies. Perovskite oxides, with compositional diversity and elemental complexity, are a classic kind of OER electrocatalysts, whereas their activity remains insufficient under the traditional adsorbate evolution mechanism (AEM) due to limited scaling relations. Herein, taking the Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) perovskite as a model system, we find a less Ru substitution strategy to boost the lattice oxygen reactivity for improved OER. The OER behavior of BSCF is greatly ameliorated as Ru doping reaches an optimal level (BSCFR0.1), delivering a lowered overpotential by 45 mV at 10 mA cm−2. Notably, such doping remarkably triggers the generation of more surface oxygen vacancies, promotes internal charge transfer, and enlarges the surface hydrophilicity, hence facilitating more lattice oxygen to participate in the surface reaction. These results demonstrate the feasibility of Ru incorporation for ameliorating the OER behavior of perovskites, and such strategy can be further leveraged to design other remarkable perovskite-based OER catalytic materials.

A coumarin containing hemicyanine-based probe for dual channel detection of cyanide ion

Cyanide(CN−) is known as one of the most toxic inorganic anions and is harmful to the environment and human health. Its wide use and severe toxicity have led to the development of highly selective cyanide detection, and quantification is desirable. A coumarin-containing hemicyanine-based probe has been developed for highly selective colorimetric and fluorometric detection of cyanide in acetonitrile and aqueous medium. The probe was characterized by 1D NMR (1H and 13C) and HRMS Spectroscopy, and the sensing properties have been studied in colorimetric and fluorometric methods. The high selectivity of the probe for CN− was established by UV–vis and fluorescence spectroscopy in the presence of other competing anions. The probe can detect cyanide as low as 0.7 μM within 90 s. A remarkable change in spectroscopic properties has been observed upon adding cyanide ion. The weakly luminescent probe emitted strongly upon the reaction with CN− which is due to the inhibition of internal charge transfer (ICT) from coumarin to indolinium moiety. Furthermore, the colour change from yellow to colourless and the appearance of a blue luminescence, which can be observed by the naked eye, provides a simple real-time method for cyanide detection, also supported by 1H NMR titration and theoretical study. Furthermore, a paper strip kit loaded with probe has been constructed for a real-time application of CN detection without any interference from other competitive analytes.

Ratiometric detection and monitoring of cyanide in biological, environmental and food samples by a novel triphenylamine-xhantane based fluorescent probe

BackgroundAs cyanide (CN−) is a significant hazard to the environment and human health, it is essential to monitor cyanide levels in water and food samples. Moreover, real-time visualization of CN−could provide an additional understanding of its critical physiological and toxicological roles in living cells. The fluorescence approach based on small organic probes is an effective way for the detection of CN−. In this approach, a triphenylamine-xhantane conjugate was applied to detect in many samples such as sewage water, soil, sprouted potato, apricot seed, and living cells. ResultsWe report a new ratiometric near-infrared fluorescent probe based on a triphenylamine-xhantane derivative for CN−sensing in many samples. The probe displays high selectivity for only CN− ions among a series of analytes. The addition of cyanide to the dicyanovinyl moiety of the probe disrupts π-conjugation followed by the interruption of internal charge transfer. Consequently, the emission peak of the probe shifts hypsochromically from 655 to 495 nm. There is a linear correlation between the emission intensity (I495) and cyanide level, with a detection limit of 0.036 μM. The probe has many advantages over many probes, such as NIR fluorescence, ratiometric response, low cytotoxicity (85.0 % cell viability up to 50.0 μM of the probe), good membrane permeability, fast response time (4.0 min), high selectivity, good photostability, and anti-interference capability. SignificanceAlthough various probes have been reported in the literature, the use of triphenylamine-xhantane unit as CN− probe has yet to be explored. The probe can detect trace levels of cyanide in many samples such as sewage water, soil, sprouted potatoes, and apricot seeds. Furthermore, it is successfully utilized for the ratiometric fluorescent bioimaging of cyanide in living cells.

Novel phenothiazine appended thiophene and pyridine for highly selective and sensitive detection of hypochlorite in aqueous and living cells

A novel colorimetric chemosensor, (Z)-3-(5-(10H-phenothiazin-10-yl)thiophen-2-yl)-2-(pyridin-2-yl)acrylonitrile (PTH-TH-PY), was synthesized through Buchwald coupling followed by Knoevenagel condensation for the detection of hypochlorite ions (OCl-). This compound demonstrates exceptional selectivity and sensitivity towards OCl- ions with a low detection limit of 0.2 nM. PTH-TH-PY's remarkable sensitivity is attributed to its effective inhibition of the internal charge transfer (ICT) mechanism. High-resolution mass spectrometry (HR-MS) and Job's plot analysis confirmed a 1:1 binding ratio between the compound and OCl-. The probe also changes from yellow to colorless upon interaction with OCl- in naked-eye. The practical utility of PTH-TH-PY was validated through TLC plate analysis and its ability to detect OCl- in various water samples. Furthermore, the compound's capacity to detect hypochlorite in live HeLa cells indicates its potential application in biological systems. These findings highlight PTH-TH-PY as a promising sensor for real-time OCl- monitoring in diverse settings, including environmental and medical contexts.

A Schiff base functioning as a highly selective colorimetric sensor for Cu2+ ion

In this study, we employed a Schiff base ligand (L = 6,6′-((1E,1′E)-(cyclohexane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(2,4-di-tert-butylphenol)) to serve as a chemosensor exclusively for detecting Cu2+ ions over other metal ions and anions in a THF:H2O mixture (7:3, v/v). L exhibits an absorption band at 330 nm, which undergoes a bathochromic shift to 377 nm upon interaction with solely Cu2+ ions, suggesting a restricted internal charge transfer process of L. Analysis via ESI-MS and Job’s plot confirmed a 1:1 stoichiometric ratio between L and Cu2+. L demonstrated the capability to detect Cu2+ ions at a concentration as low as 0.46 μM. Furthermore, we investigated the effectiveness of L in developing molecular logic gates and its applications in analyzing Cu2+ in water samples.

Efficient electrocatalytic reduction of nitrate to ammonia using Cu–CeO2 solid solution

Electrocatalytic nitrate reduction reaction (EC-NITRR) is expected to replace Haber-Bosch process for green ammonia (NH3) production. Currently, many catalysts often result in low NH3 yields and low faraday efficiencies due to the lack of active sites. In this study, Cu-doped CeO2 solid solution catalyst was prepared for EC-NITRR using transition metal ions doping. The addition of Cu significantly improved the oxygen vacancy (Ov) concentration of CeO2 and provided more active sites for NO3− catalysis. Meanwhile, the internal charge transfer capability and surface catalytic kinetics of the catalyst are enhanced by the excellent redox capability of Ce3+ and Cu+. Compared with bare CeO2, the NH3 yield of 7% Cu–CeO2 increased by 1.88 times. This work provides new ideas for the design of green and efficient catalysts for EC-NITRR by identifying the role of Cu in the mechanism of doping regulation of CeO2.

Rod-like Mn0.2Cd0.8S wrapped in foliated CeO2 promote efficient photocatalytic hydrogen evolution

The Mn0.2Cd0.8S/CeO2 heterojunction is synthesized by means of hydrothermal coupling. Short rod-like Mn0.2Cd0.8S is wrapped in leaf like CeO2 to construct a tight heterointerface, which stimulated the photocatalytic activity to the great extent. Due to the remarkable catalytic and electrochemical properties of Mn0.2Cd0.8S, the CeO2 surface active site is driven. CeO2 has excellent specific surface area, suitable pore volume aperture and Mn0.2Cd0.8S match to optimize the internal interface charge transfer path. At the same time, the heterointerface can coordinate the interface electron flow and promote the H2 reduction ability. The results show that the optimal hydrogen production of Mn0.2Cd0.8S/CeO2 with S-type heterostructure is 291.8 μmol, and the internal lattice and surface morphology of Mn0.2Cd0.8S/CeO2 are not easily damaged due to good catalytic stability. The photocatalytic mechanism of Mn0.2Cd0.8S/CeO2 is studied by finding the short distance interfacial charge transfer path and enriching the photogenerated electrons required for hydrogen evolution.

A ratiometric fluorescent probe with a large Stokes shift for rapid and sensitive detection of Hg2+ in environmental water samples and its applications in living cells and zebrafish

Detection of highly toxic mercury ions (Hg2+) in actual environmental and biological samples is of significant importance for protecting environment and human health. In this paper, a new ratiometric fluorescent probe BTIA was designed and synthesized from 3-pinone based on Internal Charge Transfer (ICT) mechanism. BTIA could selectively recognize Hg2+ over other competitive analytes with short reaction time (5 s), distinct ratiometric response, strong anti-interference ability, large Stokes shift (200 nm), and low detection limit (2.36 × 10−7 M). Furthermore, BTIA was applicable for detecting Hg2+ in actual water samples and it also performed an excellent imaging capability in living RAW264.7 cells, zebrafish and onion tissue.

Synthesis, structural, spectral, Anticancer activity, and density functional theory investigations of 2- [hydrazinylidene(phenyl)methyl]pyridine

The condensation reaction of equimolar amounts of 2-benzoylpyridine and hydrazine hydrate to produce hydrazone, 2- [hydrazinylidene(phenyl)methyl]pyridine (HPMP) with a mass spectral peak at m/z = 197. The compound showed 15N NMR peaks at 330.79, 306.64, and 110.45 ppm due to CN (azomethine), pyridine nitrogen and —NH2 nitrogen atoms. The crystal structure data, IR, and Raman studies were correlated with DFT/B3LYP/6–311++G(d,p) calculations. The compound exhibited strong fluorescence at 592 and 481 nm when excited at 290 and 210 nm, respectively. NBO Fock matrix analyses indicated the existence of different π and π* energy levels, and the molecule can undergo internal charge transfer and vibrational relaxation. The IC-50 value for HPMP was found to be 62.5 µg/ml against the MCF-7 breast cancer cell line as shown by the MTT assay. The IC-50 value for HPMP was higher than the standard doxorubicin but expected to have fewer side effects. Fluorescence microscopy analyses showed significant cell mortality compared to that of the control. The NH2 group in HPMP has been shown to interact with Asp73 (A) (2.89 Å) and ASM46 (A) (2.90 Å) through H-bonding with the DNA gyrase protein (Protein ID: 1KZN). The other selected protein residues were made hydrophobic by pyridine and phenyl rings to inactivate DNA gyrase protein. Therefore, HPMP can be used as an anticancer drug and for optical LED applications.

Surface-Assisted Laser Desorption/Ionization Mass Spectrometry with a Two-Dimensional Au Nanoparticle Array for Soft Ionization.

Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is a valuable technique for detecting small molecules in environmental and medicinal studies. We investigated dot-like and 2D-array gold nanoparticle-based SALDI-MS substrates that excite surface plasmons and enhance the desorption/ionization of sample molecules via charge transfer between the substrate and sample molecules. We aimed to optimize the nondissociative detection of sample molecules by efficiently transferring energy while suppressing excess internal energy. SALDI-MS measurements using crystal violet (CV) molecules revealed ion intensity and spectral pattern differences between the dot-like and 2D-array substrates. SALDI-MS measurements using dot-like substrates suggested two desorption/ionization processes: internal energy supply and charge transfer between the substrate and sample molecules. However, SALDI-MS measurements using 2D-array substrates suggested that the internal energy supply was suppressed. As a result, the dot-like substrate provided higher desorption/ionization efficiency but increased fragmentation, whereas the 2D-array substrate was suitable for highly sensitive and nondissociative SALDI-MS measurements. This study contributes to the optimization of SALDI-MS measurements and advances our understanding of energy transfer and sample molecule dissociation.

A Naphthalimide Based "Turn-ON" Probe for Wash-Free Imaging of Lipid-Droplet in Living Cells With an Excellent Selectivity.

The impacts of dimethylation of 4-Amino-1,8-Naphthalimide (ANI) on its photophysical properties are reported. The resulting 4-DiMe-ANI displays completely different fluorescence properties, conferring it ability to selectively label lipid droplets in living cells. A comprehensive photophysical study revealed that this selectivity arises from an Internal Charge Transfer favored in lipophilic media to the detriment of a non-emissive TICT in more polar media. This results in a very high "LDs/Cytosol" signal ratio, enabling LDs to be imaged with an excellent signal-to-noise ratio, and positioning its performance above that of the BODIPY 493/503 commonly used to image LDs.

Synergistic Effects of Confinement Structure and Local‐Expanded Interlayer Spacing in Fe2Mo3O8@C@MoS2 Toward High‐Efficient Sodium Ion Storage

AbstractDeveloping multicomponent composite materials with delicate morphology and tailored structure is of vital importance for designing advanced sodium‐ion batteries (SIBs). Herein, a confinement‐structured Fe2Mo3O8@C@MoS2 with local‐expanded interlayer spacing is designed via high‐temperature phase transition from FeMoO4 to Fe2Mo3O8 and the tactically introducing dopamine molecules into the interlayer of MoS2 nanosheets. By analysis of the in situ generated solid electrolyte interphase film in different electrolytes, the favorable compatibility of Fe2Mo3O8@C@MoS2 in ether‐based electrolytes is well illustrated. Importantly, the sodium storage mechanism and detailed structural evolution of Fe2Mo3O8 are established for the first time by in situ X‐ray diffraction. Furthermore, theoretical calculations indicate the unique structure facilitates internal charge transfer and enhances Na+ adsorption ability. Thanks to the unique confinement structure, local‐expanded interlayers and robust framework, the Fe2Mo3O8@C@MoS2 composite achieves a high reversible specific capacity of 636 mAh g‒1 at 0.1 A g‒1, excellent rate capability (301 mAh g‒1 at 5.0 A g‒1) and ultralong cycling stability (365 mAh g–1 after 6000 cycles at 2.0 A g–1). The study provides an essential understanding of the Na storage mechanism of Fe2Mo3O8 and a promising strategy for constructing high‐performance anodes for SIBs.

Photocatalytic reduction of biomass‐derived aldehydes over Pt‐loaded on NiIn bimetallic oxides under light‐emitting diode lighting at mild conditions

Photocatalytic conversion of renewable biomass‐derived aldehydes into high‐valued chemicals is a promising path to meet the growing demand for clean energy and chemical resources. However, the approach still faces challenges, such as limited reaction types and low utilization rates due to the complex functional groups and involved polytropic reaction. In the present work, we developed a catalyst of Pt nanoparticles (Pt NPs) supported on a NiO–In2O3 bimetallic oxide (denoted as Pt/NiInOx) for photocatalytic hydrogenation of furfural (FAL) to furfural alcohol (FOL). Owing to the excellent band structure and efficient internal charge transfer on the p–n heterojunction in the catalyst, the highest 99.9% yield to FOL was obtained over the Pt/NiInOx under a light‐emitting diode (LED) light at low temperatures as 273 K. The combination of ·H dissociated from H2 and oxygen vacancy work synergically to adsorb, activate, and converse C=O to the C–O group. The photocatalytic system presents a highly efficient approach for the rapid hydrogenation of biomass‐based aldehydes under a low LED light radiation intensity at a low temperature. The work is expected to serve as an important reference in constructing bimetallic oxide‐supported active metals, enabling efficient separation of photogenerated electrons and holes, and offering oxygen vacancies in various photocatalytic reactions.

Recent advances in high charge density triboelectric nanogenerators

Abstract Triboelectric materials with high charge density are the building-block for the commercial application of triboelectric nanogenerators (TENGs). Unstable dynamic processes influence the change of the charge density on the surface and inside of triboelectric materials. The charge density of triboelectric materials depends on the surface and the internal charge transfer processes. The focus of this review is on recent advances in high charge density triboelectric materials and advances in the fabrication of TENGs. We summarize the existing strategies for achieving high charge density in triboelectric materials as well as their fundamental properties. We then review current optimization methods for regulating dynamic charge transfer processes to increase the output charge density: first, increasing charge injection and limiting charge dissipation to achieve a high average surface charge density, and second, regulating the internal charge transfer process and storing charge in triboelectric materials to increase the output charge density. Finally, we present the challenges and prospects in developing high-performance triboelectric materials.

Aqueous phosphate detection in real samples using NIR-triggered Diamino Bis-Benzimidazoquinoline fluorescence sensor: An experimental and theoretical approach

The present work reports the design, synthesis, and sensing applications of Diamino bis-benzimidazoquinoline (DA-BISQ) derivatives. These compounds were synthesized in appreciable yield and characterized by FT-IR, 1H, and 13C NMR spectral and mass spectrometry. Optical studies revealed intriguing dual excitation properties: single excitations at λex 330-386 nm and double excitations at λex 660-772 nm in 10 % ethanol-water medium. The near-infrared excitation region λex 660-772 nm was particularly focused on the detection of F¯, Cl¯, Br¯, I¯, AcO ̄, ClO4¯, NO3¯, and HPO4¯ anions. Notably, selective fluorescence quenching "OFF" responses were observed for geometric anions like AcO¯, ClO4¯, NO3¯, and HPO4¯. Interestingly, the pyridine spacer-containing derivative 1c exhibited a unique fluorescence "OFF-ON'' response for the phosphate ion. Cyclic voltammetry titration further corroborated the binding affinity towards phosphate. To demonstrate practical applicability, a thin-film strip of receptor 1c was fabricated and tested for effective phosphate sensing in human blood serum samples. Density functional theory calculations were performed to elucidate the sensing mechanism with the phosphate anion. The combined experimental and theoretical results suggest an internal charge transfer process between the receptor and the anion.