Charge Transfer Energy Research Articles

Negative Charge Transfer Energy in Correlated Compounds

Negative Charge Transfer Energy in Correlated Compounds

Laser-Induced Regeneration of Spent LiMn2O4 Cathode Into High-Performance Ni-Doped LiMn2O4 Cathode.

The rapid increase in lithium-ion battery (LIB) production, fueled by the rise of electric vehicles, highlights significant challenges in managing end-of-life LIBs, particularly regarding environmental impact and waste management. Traditional recycling methods, such as pyrometallurgical and hydrometallurgical processes, are energy-intensive and consume substantial reagents. In this study, a laser-assisted regeneration method is introduced for LiMn2O4 (LMO) cathodes, enabling in situ Ni doping into spent LMO cathodes (r-LMO-Ni) to enhance electrochemical performance. Surface Ni-doping improves interfacial processes and reduces capacity loss at lower temperatures by creating a new interface with a lower charge transfer energy barrier. The r-LMO-Ni cathode surpasses pristine LMO cathodes, achieving a specific capacity of 112.95mA h g-1 at 1 C and retaining 95.1% of its capacity after 200 cycles at 0 °C. A techno-economic analysis supports the feasibility of this laser-assisted regeneration approach, offering an innovative pathway for upcycling spent cathodes and developing next-generation Mn-based cathodes.

A coumarin-naphthalimide-based fluorescent probe for the ratiometric detection of Hg2+ utilizing an ICT-FRET mechanism

Mercury, as one of the most toxic elements in environmental and biological samples, can poses a grave threat to the integrity of the nervous, reproductive, immune, and digestive systems. Hence, it is significant to exploit convenient and rapid fluorescent probes featuring high sensitivity and selectivity for monitoring the concentration level of mercury ions (Hg2+). In this paper, a ratiometric fluorescent probe for Hg2+ based on intramolecular charge transfer (ICT) and fluorescence resonance energy transfer (FRET) mechanisms was developed by using coumarin ad energy donor and naphthalimide as energy acceptor, and thionocarbonate as the recognizing group for Hg2+. When the probe alone was present in the system, the thionocarbonate group of the probe prevented the electron transfer and the ICT process was off, thus preventing the FRET process of the probe as well. The probe alone emitted the intrinsic blue fluorescence of coumarin upon excitation at 397 nm. After providing Hg2 the thionocarbonate unit reacted with Hg2+, which restored the ICT process of the naphthalimide donor, and the FRET process in turn took place. Upon adding Hg2+, the probe emitted yellow fluorescence. In addition, the fluorescence intensity ratio at 548 nm and 476 nm (I548 nm/I476 nm) of the probe linearly corrected with the concentration of Hg²⁺ ions in the range of 0.1–12 μM. A limit of detection of 0.055 μM was obtained. Meanwhile, the probe exceptional recognized Hg2+ across a broad pH range (pH=4.00–10.00), including physiological pH. Cellular studies further confirmed the probe's negligible cytotoxicity and its potential for ratiometric fluorescence imaging of intracellular Hg²⁺ ions in A549 cells. In addition, the probe was loaded on filter paper to make test strips and combined with a smartphone to achieve rapid visual quantitative detection of Hg2+.

Applicable Descriptors under Weak Metal‐Oxygen d–p Interaction for the Oxygen Evolution Reaction

AbstractThe oxygen evolution reaction (OER) plays a crucial role in water electrolysis and renewable energy conversion processes. Descriptors are utilized to elucidate the structure‐performance relationships of OER catalytic materials, yet each descriptor exhibits specificity to particular systems. Currently, there is a lack of effective descriptors to describe the relationship between electronic structure and OER performance in ionic systems. This study reveals for the first time that widely used OER descriptors, the d‐band center and charge transfer energy, are limited in their effectiveness for oxide systems dominated by ionic bonds, in which ionic interactions significantly enhance or suppress the catalytic activity. Furthermore, composite descriptors tailored for ionic systems are proposed, with findings extended to complex multi‐component and high‐entropy oxides. The results indicate that the metal d‐band unoccupied states parameter and the active states parameter can serve as effective OER descriptors for ionic catalytic materials. This work addresses the gap in OER descriptors for ionic systems, offering a new theoretical foundation and guidance for the development of efficient OER catalytic materials.

Assessment of Charge Transfer Energies of Noncovalently Bounded Ar-TCNE Complexes Using Range-separated Density Functionals and Double Hybrid Density Functionals.

Charge Transfer (CT) molecular complexes have recently received much attention in a broad variety of fields. The time-dependent density functional theory (TDDFT), which is essential for studying CT complexes, is a well-established tool to study the excited states of relatively large molecular systems. However, when dealing with donor-acceptor molecules with CT characteristics, TDDFT calculations based on standard functionals can severely underestimate the excitation energies. Here, we demonstrate that TDDFT can reliably be used for the calculations of the excitation energies of charge transfer molecular complexes, such as, Ar-TCNE (TCNE = tetracyanoethylene; Ar= benzene, naphthalene, anthracene, etc.) when using range-separated DFT and range-separated double-hybrid DFT functionals. The interactions between the donor-acceptor moieties of these molecular complexes are also studied and the relationship between the interaction and the charge transfer energies are shown here.

Applicable Descriptors under Weak Metal-Oxygen d-p Interaction for the Oxygen Evolution Reaction.

The oxygen evolution reaction (OER) plays a crucial role in water electrolysis and renewable energy conversion processes. Descriptors are utilized to elucidate the structure-performance relationships of OER catalytic materials, yet each descriptor exhibits specificity to particular systems. Currently, there is a lack of effective descriptors to describe the relationship between electronic structure and OER performance in ionic systems. This study reveals for the first time that widely used OER descriptors, the d-band center and charge transfer energy, are limited in their effectiveness for oxide systems dominated by ionic bonds, in which ionic interactions significantly enhance or suppress the catalytic activity. Furthermore, composite descriptors tailored for ionic systems are proposed, with findings extended to complex multi-component and high-entropy oxides. The results indicate that the metal d-band unoccupied states parameter and the active states parameter can serve as effective OER descriptors for ionic catalytic materials. This work addresses the gap in OER descriptors for ionic systems, offering a new theoretical foundation and guidance for the development of efficient OER catalytic materials.

Exploring the Electronic Interactions of Adenine, Cytosine, and Guanine with Graphene: A DFT Study.

This study has provided new insights into the interaction between graphene and DNA nucleobases (adenine, cytosine, and guanine). It compares how each nucleobase interacts with graphene, examining their selectivity and binding energy. The research also explores how these interactions impact the electronic properties of graphene, showing potential applications in graphene-based biosensors and DNA sequencing technologies. Additionally, the findings suggest potential uses in DNA sensing and the functionalization of graphene for various biomedical applications. This study employs density functional theory (DFT) methods, utilizing the B3LYP functional with the 6-311G basis set, to explore the electronic interactions between DNA nucleobases (adenine, cytosine, and guanine) with pure graphene (Gr). We investigate various properties, including adsorption energy, HOMO-LUMO energy levels, charge transfer mechanisms, dipole moments, energy gaps, and density of states (DOS). Our findings indicate that cytosine interacts most favorably with graphene through its oxygen site (Gr-Cyt-O), exhibiting the strongest adsorption. Additionally, adenine's interaction significantly enhances its electronegativity and chemical potential, particularly at the nitrogen position, while decreasing its electrophilicity. Guanine, characterized by the smallest energy gap, demonstrates the highest conductivity among the nucleobases. These results suggest that graphene possesses advantageous properties as an adsorbent for guanine, highlighting its potential applications in biosensor technology.

Photoinduced charge transfer and excitonic energy transfer in the CuInS2/ZnS/MoS2 heterotrilayer

Photo-induced charge transfer is the key process of many applications such as photovoltaics, photodetection, and light-emitting devices. With the outgrowth of a new class of low-dimensional semiconductors, i.e., monolayer transition metal dichalcogenides and semiconductor nanocrystals, charge transfer at the 2D/0D heterostructures has drawn many efforts because of the outstanding optical and electrical properties. This paper studies the dynamics of excitons of the CuInS2/ZnS/MoS2 heterotrilayer through femtosecond time-resolved transient absorption spectroscopy. The electron and hole transfer are observed by selectively exciting the electrons with tunable pump wavelengths. The exciton lifetimes are obtained on the picosecond scale. This work provides clues on exploring the non-toxic optoelectronic devices based on the CuInS2/ZnS/MoS2 heterotrilayer.

Solid-State Replacement in the Polyhedra of Cu2+, Ni2+, and Co2+ upon Dehydration/Rehydration Processes Associated with a Color Change in Three Isomorphous Materials with 5,5'-Indigodisulfonate.

The significance of thermochromic materials in a wide range of applications makes their research and development highly desirable. Herein, three new thermochromic isomorphous supramolecular materials based on the 5,5'-indigodisulfonate ion of the indigo carmine dye, with formulas [Cu(H2O)6](C16H8N2O8S2)·2H2O (1), [Ni(H2O)6](C16H8N2O8S2)·2H2O (2), and [Co(H2O)6](C16H8N2O8S2)·2H2O (3), are reported. These materials exhibit thermochromic properties, with a color change from red-bronze to grayish-red after the first step of their dehydration process completed around 80 °C (conversion of 1 to [Cu(H2O)2(C16H8N2O8S2) (1')]), and then, this grayish-red color becomes lighter after the second step, which is completed around 230 °C (conversion of 1' to [Cu(C16H8N2O8S2)] (1d)). The 1, 1', and 1d phases have different crystal structures but similar tetragonal bipyramidal geometries around the copper ions. These dehydrated phases rehydrate by exposure to a higher humidity level. Solid-state UV-visible spectroscopy, thermogravimetric analysis, infrared spectroscopy, and X-ray powder diffraction analyses shed light on the structural and chemical changes accompanying the color change of 1, 2, and 3 to their partial dehydrated phases 1', 2', and 3', respectively. These transformations occur with the small modification of the charge transfer energy in the 5,5'-indigodisulfonate ions, indicating the potential of dye-based metall-organic materials for chromic properties.

Reducing Dead Species by Electrochemically‐Densified Cathode‐Interface‐Reaction Layer towards High‐Rate‐Endurable Zn||I‐Br Batteries

Interhalogen‐involved aqueous Zn||halogen batteries (AZHBs) are latent high‐energy systems for grid‐level energy storage, yet usually suffer from poor high‐rate endurability caused by the formation of “dead species”. Herein, via an electrochemically‐densified cathode‐interface‐reaction layer (CIRL), Zn||I‐Br batteries involving interhalogen reactions between the I2 cathode and Br‐ from the electrolytes are initially achieved with excellent high‐rate endurability. Different from that in diluted electrolytes, the CIRL formed in Br‐‐concentrated electrolyte is denser and water‐lean, which enables halogen species conversion with a more rapid charge transfer and lower activation energy. More importantly, the CIRL robustly affords a decent I2 conservation by accelerated conversion kinetics and limited species diffusion, thereby endowing the Zn||I‐Br batteries with an ultralong high‐rate lifespan. The electrochemical mechanism is sufficiently verified by multiple spectral characterizations. Consequently, Zn||I‐Br batteries in Br‐‐concentrated (20 m) electrolytes exhibit an overwhelming rate capability and lifespan to those in Br‐‐diluted (2 m) electrolytes. Typically, when cycled at a large current density of 10 A g‐1, an ultralong lifespan of over 25,000 cycles is achieved with a high retention of 98.3%. This study provides new insight into the CIRL‐dictated active species conservation for high‐rate endurable AZHBs, which could apply to other high‐energy interhalogen batteries.

Reducing Dead Species by Electrochemically-Densified Cathode-Interface-Reaction Layer towards High-Rate-Endurable Zn||I-Br Batteries.

Interhalogen-involved aqueous Zn||halogen batteries (AZHBs) are latent high-energy systems for grid-level energy storage, yet usually suffer from poor high-rate endurability caused by the formation of "dead species". Herein, via an electrochemically-densified cathode-interface-reaction layer (CIRL), Zn||I-Br batteries involving interhalogen reactions between the I2 cathode and Br- from the electrolytes are initially achieved with excellent high-rate endurability. Different from that in diluted electrolytes, the CIRL formed in Br--concentrated electrolyte is denser and water-lean, which enables halogen species conversion with a more rapid charge transfer and lower activation energy. More importantly, the CIRL robustly affords a decent I2 conservation by accelerated conversion kinetics and limited species diffusion, thereby endowing the Zn||I-Br batteries with an ultralong high-rate lifespan. The electrochemical mechanism is sufficiently verified by multiple spectral characterizations. Consequently, Zn||I-Br batteries in Br--concentrated (20 m) electrolytes exhibit an overwhelming rate capability and lifespan to those in Br--diluted (2 m) electrolytes. Typically, when cycled at a large current density of 10 A g-1, an ultralong lifespan of over 25,000 cycles is achieved with a high retention of 98.3%. This study provides new insight into the CIRL-dictated active species conservation for high-rate endurable AZHBs, which could apply to other high-energy interhalogen batteries.

Synthesis and characterization of new organometallic lanthanides metal complexes for photodynamic therapy

New Schiff base ligand: 4-methoxy salicaldhyde-2-2-phenyl-hydrazono acetaldehíyde prepared by facile method. The molecular structures characterized by elemental analysis and proton magnetic resonance spectra (1H-NMR spectra). This spectra at the chemical shifts (3.5–10.39 ppm) confirmed the types and the numbers of protons. The sharp melting point at the range 110–112 °C confirmed purity. New optically active metal (samarium, terbium and gadolinium) complexes of the Schiff base synthesized in a one pot reaction. Vibrational IR spectra confirmed functional groups. Scanning electron microscopy micrographs confirmed that the modified microstructure of the metal complexes differed in morphology than the ligand. Powder X-ray diffraction patterns confirmed good crystalline structure. The optically activity of the solid metal complexes confirmed from electronic absorption spectra. The UV absorbance band at the wavelength range 280–390 nm and the intense phosphorescence bands up to 830 nm enabled application in photo dynamic therapy for apoptosis cancer cells by conversion triplet oxygen in the tissues into reactive singlet oxygen. Low charge transfer energy: 2.59–2.61 eV, high molar extinction coefficients (ε) at the order of magnitude \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{10}^{6}$$\\end{document} M− 1 cm− 1 and the intense phosphorescence bands reflected good photodynamic activity. The metal complexes are thermally stable.

Supporting IrOx on stable La, Nb-TiO2 with enhanced electron transport for efficient acidic water oxidation

In the evolution of proton exchange membrane (PEM) electrolysis, the development of durable electrocatalysts for the acidic oxygen evolution reaction (OER) is crucial. This work introduces an electrocatalyst with a core–shell architecture, consisting of amorphous iridium oxide (IrOx) supported on lanthanum (La) and niobium (Nb) co-doped titanium dioxide (denoted as La, Nb-TiO2@IrOx). The resultant La, Nb-TiO2@IrOx, synthesized via a hydrothermal method, exhibits enhanced OER activity and remarkable durability in acidic media. The theoretical calculations provide insight into the enhanced performance of La, Nb-TiO2@IrOx, revealing a narrowed bandgap and improved conductivity due to co-doping. Additionally, there is an increase in charge transfer and binding energy at the heterointerface. As a result, electrochemical evaluations show a significant reduction in overpotential and enhancement in long-term stability, achieving an overpotential of 234 mV at 10 mA cm−2 and maintaining impressive stability for 150 h. These findings underscore the potential of La, Nb-TiO2 as a robust platform for acidic OER electrocatalysts, offering valuable insights into the design of durable and efficient systems for energy conversion applications and advancing the development of next-generation technologies.

Investigating the impact of acetylenic linkage in C20 fullerene: Utilization in optoelectronic devices and as anode material

This study delves into the diverse characteristics of C80 fulleryne, derived from the incorporation of acetylenic linkages into each chain of the smallest fullerene, C20. Utilizing advanced theoretical computations, we confirm the stability of C80 fulleryne. Notably, its possession of a finite energy gap (0.743 eV) categorizes it as a semiconductor. Further enlightenment into its structural stability, bonding and reactivity stems from an exploration of different energy components, topological descriptors of electron density and chemical reactivity parameters. C80 fulleryne can act as radical scavenger owing to its higher electron affinity (5.5 eV). Spectral analysis revealed the C80 fulleryne’s absorption within the near-infrared region and its intriguing optical transparency with negligible loss in specific regions of the electromagnetic spectrum. Additionally, our investigation scrutinized the viability of C80 fulleryne as an anode material in Lithium-ion batteries. The presence of low adsorption energy (−1.693 eV) and significant amount of Bader charge transfer (0.917 e) between Li-ion and C atoms of C80 fulleryne confirms that Li-ion gets chemisorbed on the C80 fulleryne. Remarkably, this cage acts as a storehouse to host 12 Li ions, precisely one for each of its constituent pentagons within the C80 fulleryne structure, bearing a theoretical capacitance of 335 mAhg−1.

Customization of 2D Atomic-Molecular Heterojunction with Manipulatable Charge-Transfer and Band Structure.

Manipulating the properties of 2Dmaterials through meticulously engineered artificial heterojunctions holds great promise for novel device applications. However, existing research on the crucial charge-transfer interactions and energy profile regulation is predominantly focused on 2D van der Waals structures formed via weak van der Waals forces, limiting regulatory efficiency at high costs. Herein, a refined atomic-molecular heterojunction strategy featuring strong covalent bonds between organic molecule and 2D violet phosphorus (VP) atomic crystal is developed, which enables enhanced charge-transfer dynamics and customizable band structure regulation at the molecular level. Both experimentally and theoretically, it is demonstrated that grafting efficiency, charge redistribution, and energy gap regulation critically depend on organic electronegativity, providing a low-cost yet high-efficiency regulatory effect on a large scale. As a proof of concept, the novel VP-molecular heterojunctions exhibit optimized performance in diverse application domains, presenting a general platform for future high-performance device applications.

Facilitating superior electrochemical efficacy and ultra rapid kinetic in Co/Ni-free layered oxides for sodium-ion batteries with phosphate-growing layer fast ion conductors

Co/Ni-free layered oxides have garnered significant interest due to their environmental friendliness and facile synthesis methodologies, while facing major challenges of inferior cycling stability and rate capability. Addressing these drawbacks necessitates the enhancement of the surface properties of Co/Ni-free layered oxides. This work introduces a Co/Ni-free layered oxide, Na0.67Mn0.65Fe0.3Al0.05O2 (NMFA), which has been subjected to phosphate-based surface engineering. This targeted surface modification aims to augment the specific surface area and establish a protective layer on NMFA. Such improvements are critical for expanding the effective electrochemical reaction zone, broadening sodium ion diffusion pathways, curtailing the P2-OP4 phase transition, and reducing the activation energy for interfacial charge transfer. This multifaceted surface treatment epitomizes the ingenious design and realization of advanced Co/Ni-free layered oxide cathode materials through straightforward processing techniques. Notably, the NMFA subjected to 3%-AlPO4 surface modification demonstrated an initial discharge capacity of 189.1 mAh/g at 0.1C, maintaining its capacity after 500 cycles at 10C. Additionally, DFT calculations corroborate that such surface growth can bolster electrical conductivity, restrain oxygen liberation and foster sodium ion migration. This elucidates that the phosphate growth layer serves as the oxygen reservoir. Accordingly, this investigation propounds a promising avenue to circumvent the challenges confronting Co/Ni-free layered oxides, thus paving the way for the development of high-performance cathode materials.

Mott interactions driven insulating behaviour in ruthenium based double perovskites: A2SmRuO6 (A = Ba & Sr)

Double perovskites (DP’s) are important for understanding the diverse physical properties arising from strongly correlated interactions. According to experimental observations, the DP’s A2SmRuO6 (A = Ba & Sr) are insulators; however, first-principles calculations using GGA approximations show that they are metallic. We observed a band gap (Eg) opening of 1.3 eV for Ba2SmRuO6 (BSRO) and 1.4 eV for Sr2SmRuO6 (SSRO) upon the insertion of Hubbard parameter (U) in the theoretical computations for accounting the electron-electron interactions. Further investigations using core-level spectroscopy reveal Eg of 1.05 eV for BSRO and 0.85 eV for SSRO. Furthermore, the calculations for Δ (charge transfer energy), U (coulomb repulsion energy), and W (bandwidth) from the combined spectra show U < Δ and U/W > 1.15, which confirms these compounds be classified as Mott-Hubbard insulators. These results expand our understanding of the strongly correlated compounds around the Fermi level, which might have applications in optoelectronics.

Study on the effects of configuration entropy to electrochemical properties of A2BO4-type cathode materials for SOFCs

High entropy oxides are one of the research topicalities in the field of SOFC. However, the relationship between configuration entropy and the electrochemical properties of these materials is not well understood. Here, a medium entropy material (La0.2Pr0.2Nd0.2Sm0.2Eu0.2)2CuO4 ((Ln0.2)2CuO4) derived from Nd2CuO4 material is designed. It was found that increasing the configuration entropy of the A-site promotes the production of highly reactive/concentrated non-stoichiometric oxygen and increases the covalency of the Cu3d-O2p orbital. The polarization impedance of (Ln0.2)2CuO4 is 0.92 Ω cm2 at 700 °C, which is smaller than that of Nd2CuO4 (1.8 Ω cm2 at 700 °C). The peak power density of single cells NiO-YSZ|YSZ|GDC|cathode is 526 mW cm−2 at 700 °C within 60 h of stable operation at 0.5 V. First-principles calculations demonstrate that (Ln0.2)2CuO4 has lower charge transfer energy, which promotes the electronic conduction. Furthermore, the dissociation energy of adsorbed oxygen (Oad) on the surface of (Ln0.2)2CuO4 is 2.24 eV, which is smaller than that of Nd2CuO4 (2.26 eV). These results suggest that the entropy-increasing strategy can enhance the electrocatalytic performance.

A General Photoactive H-Bonding EDA Complex Model Drives the Selective Hydrothiolation and Hydroxysulfenylation of Carbonyl Activated Alkenes.

Excitation of photoactive electron donor-acceptor (EDA) complexes to generate radical is a promising approach in radical chemistry. In this study, we introduce a new model of H-bonding EDA complexes for the selective hydrothiolation and hydroxysulfenylation of carbonyl-activated alkenes with diverse thiols under visible light conditions. The reliability of this H-bonding EDA complex model has been confirmed by meticulous experimental and theoretical calculations. Mechanistic investigations have revealed the significant influence of the solvent in determining whether the excitation of photoactive H-bonding EDA complex leads to charge transfer (CT) or energy-charge transfer (En-CT), thereby controlling Markovnikov and anti-Markovnikov selectivity. Notably, the Quantum Theory of Atoms in Molecules (QTAIM) analysis clearly shows that the excited state of the C=O-H-S EDA complex involves closed-shell partially covalent interactions.

A General Photoactive H‐Bonding EDA Complex Model Drives the Selective Hydrothiolation and Hydroxysulfenylation of Carbonyl Activated Alkenes

AbstractExcitation of photoactive electron donor−acceptor (EDA) complexes to generate radical is a promising approach in radical chemistry. In this study, we introduce a new model of H‐bonding EDA complexes for the selective hydrothiolation and hydroxysulfenylation of carbonyl‐activated alkenes with diverse thiols under visible light conditions. The reliability of this H‐bonding EDA complex model has been confirmed by meticulous experimental and theoretical calculations. Mechanistic investigations have revealed the significant influence of the solvent in determining whether the excitation of photoactive H‐bonding EDA complex leads to charge transfer (CT) or energy‐charge transfer (En‐CT), thereby controlling Markovnikov and anti‐Markovnikov selectivity. Notably, the Quantum Theory of Atoms in Molecules (QTAIM) analysis clearly shows that the excited state of the C=O−H−S EDA complex involves closed‐shell partially covalent interactions.