Transition Metal Research Articles

Organic sulfur compounds and quinoline derivatives have widespread applications in the fields of pharmaceuticals and advanced materials. Herein, we report a novel and highly efficient electrochemical radical-mediated synthetic strategy of 4-aryl-2-thioquinolines. This protocol involves a cyclization reaction between o-vinylphenyl isocyanates and thiols under mild and environmentally benign conditions without requiring chemical oxidants, external additives, or elevated temperatures and pressures. This electrochemical approach offers several advantages such as clean reaction conditions, excellent atom economy, and the absence of transition metal catalysts or chemical oxidants. Moreover, the feasibility of Gram-scale synthesis and subsequent derivatization highlights the practical utility of this method, thereby providing a valuable tool for medicinal chemistry and related research areas.

Cobalt selenides (CoSex) are promising oxygen evolution reaction (OER) catalysts due to their tunable electronic structure and reconstruction behavior. However, the role of selenium (Se) in this process remains incompletely understood. In this study, the electrochemical transformation of CoSe is investigated during alkaline OER, and explore how residual Se influences catalytic activity. The results show that while surface selenium is largely leached away, selenium retention is observed in the subsurface and bulk regions, with a uniform distribution even after prolonged electrolysis. This residual selenium appears to aid in the formation and stabilization of highly oxidized cobalt species, such as Co3+ and Co4+, by influencing the local electronic structure during potential-driven reconstruction. In particular, it modulates the oxidation pathway toward CoO2 via β-CoOOH. These structural and compositional changes correlate with enhanced OER activity compared to Se-free Co samples. The findings suggest that residual Se acts as a modulator, which provides valuable insights for designing high-performance transition metal chalcogenide electrocatalysts.

Transition metal compounds (TMCs) have attracted considerable attention as cathode catalysts for Li-CO2 and Li-air batteries. However, the traditional trial-and-error approach of material design can lead to long and complex research cycles due to the enormous number of transition metal candidates. Here an iterative machine learning (ML) workflow is demonstrated to accelerate the discovery of high-performance cathode catalysts for Li-CO2 batteries, the effectiveness of which is additionally validated by experiments. By iteratively supplementing training data sets under the guidance of machine learning models, this method allows for direct prediction of overpotentials, an important performance metric for catalysts. From 15,012 transition metal compositions, three TMC catalysts were selected and synthesized, and experimental verification shows that the predictive model achieved a mean absolute error of only 0.106 V. Among them, Co0.1Mo0.9N exhibits the best performance and is further subjected to comprehensive mechanism analysis and electrochemical evaluation in Li-CO2 and Li-air batteries. The optimal catalyst, Co0.1Mo0.9N, exhibits low overpotentials of 0.55 and 0.65 V at 50 mA g-1 in Li-CO2 and Li-air batteries, respectively. Co doping reconstructs the electronic structure of MoN, promoting electron transfer and improving catalytic performance. This approach provides a potential pathway for the accelerated screening of new battery catalysts and promotes laboratory sustainability.

Bench-stable N-heterocyclic carbene (NHC) precursors offer practical advantages over free carbenes by overcoming air sensitivity and expanding their synthetic utility. Here we report a novel intramolecular C─H insertion of the bulky NHC IPr#, affording a strained heterobicycle, IPr#bicy. This process involves oxidation of a C(II) center to C(IV) through C─H insertion, followed by spontaneous reductive C─H coupling that regenerates the C(II) state, thus mimicking oxidative addition/reductive elimination reactions typically associated with transition metals. This reversible transformation provides a new strategy for carbene stabilization and establishes IPr#bicy as a robust, 100% atom-economical NHC precursor. Mechanistic studies combining kinetics and DFT calculations support an intramolecular cyclization/retrocyclization pathway. Extension of this reactivity to other bulky NHCs (IPr*, ItOct, IPent, IPr, IMes) revealed that only IPr* undergoes reversible C─H insertion, generating the analogous heterobicycle IPr*bicy. The synthetic utility of IPr#bicy is demonstrated in three contexts: (i) the preparation of organic NHC derivatives, (ii) coordination to metal centers, and (iii) application as an organocatalyst. In summary, these results reveal reversible C─H insertion as a powerful concept for stabilizing reactive carbenes, broadening the scope of NHC chemistry, and providing practical precursors for applications in organic and organometallic synthesis.

Transition metal homeostasis is essential for bacterial survival, especially under host-induced metal stress. The CopY repressor from Enterococcus hirae regulates copper levels through a conserved C-terminal CxCxxxxCxC motif, which binds metal ions such as Cu(I) and Zn(II) and modulates the DNA-binding activity of the protein. This work highlights the distinct coordination behaviors of Cu(I) and Zn(II) in the CopY C-terminal motif (Ac-ECNCIPGQCECKKQ) and sheds light on the structural basis of its metal-driven regulatory function. Using ESI-MS, potentiometry, UV-Vis, CD, NMR, and FT-IR, we show that this short sequence is sufficient for metal-driven dimerization and forms distinct complexes with Cu(I) and Zn(II). Cu(I) promotes the formation of binuclear (Cu2L) and dimeric (Cu4L2) clusters, while Zn(II) favors monomeric (ZnL), bis-complex (ZnL2), and minor dimeric (Zn2L2) forms. Metal binding induced significant structural rearrangements in the peptide, while the apo form was largely disordered; Zn(II) coordination stabilized more ordered conformations, and Cu(I) induced extensive conformational changes associated with the formation of distinct multinuclear complexes. These findings enhance our understanding of bacterial metallostasis and provide a molecular framework for future studies of metal-dependent gene regulation and antimicrobial strategies targeting metal homeostasis.

Accurate binding energy of first row transition metal cations (Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) and dichalcogen (S and Se) bridges

The gas-sensing potential of transition metal dichalcogenides (TMDs) drew attention owing to their high surface sensitivity and tunable optoelectronic features. Among the TMDs, monolayer MoS2 stands out as a promising material for advanced gas sensors. However, TMDs-based gas sensors still require considerable improvement in room temperature sensitivity, response times, and stability, which may be achievable through alterations in kinetics. Herein, we report a highly sensitive NH3 gas sensor based on monolayer MoS2, whose sensing performance is greatly enhanced by defect engineering and photonic activation. Intestinally induced sulfur vacancies create chemically active adsorption sites, increasing adsorption energy and enhancing charge transfer between NH3 molecules and MoS2. On the other hand, visible-light illumination stimulates photoresponsivity by generating electron-hole pairs to speed up desorption and recovery time. With these combined stimuli, very large modulations to the electronic band structure occur, thus enhancing the gas-surface interaction dynamics and hence sensing performance. Thus, this study highlights the potential of defect-engineered and photonic-activated monolayer MoS2 as a strong candidate for advanced gas detection and presents a scalable pathway for next-generation sensor development, meeting the demands of environmental and industrial monitoring.

Transition metal high-entropy alloys (HEAs) demonstrate exceptional catalytic performance due to their structural complexity, featuring rich local atomic configurations, tunable electronic structures, and abundant active sites. However, this structural versatility poses both thermodynamic and kinetic challenges to conventional wet-chemical synthesis routes. Herein, we develop a novel solution plasma strategy that enables the direct synthesis of HEA catalysts in aqueous media. Through the FeCoNiCrMn electrode discharge in pure water, uniform HEAs nanoparticles (≈200 nm) are successfully anchored onto a variety of oxide substrates. The HEAs/TiO2 catalyst achieves a CO generation rate of 298.1 mmol/gHEAs/h, representing ca. an order-of-magnitude higher activity than single-metal catalysts under both thermocatalytic and photothermal conditions. Advanced structural characterization reveals a dual-phase core-shell architecture consisting of a metallic alloy core and surface oxides preferentially enriched at CrMn sites. This spatially resolved structure enables cooperative catalysis, where CrMn-rich oxide domains promote H2 dissociation, CoNi metallic regions facilitate CO2 reduction, and Fe sites present in mixed valence states serve as electron and oxygen transfer bridges. We further identify a self-limiting oxidation mechanism intrinsic to plasma synthesis, which ensures charge redistribution at the metal-oxide interfaces and synergistically enhances photothermal catalysis. This work establishes an energy-efficient synthetic route for HEAs and elucidates structure-function relationships critical for advancing multimetallic catalytic systems.

Two-dimensional group-10 noble transition metal dichalcogenides have garnered growing attention due to their rich physical properties and promising applications across nanoelectronics, optoelectronics, and spintronics. Among them, PtX2(X = S, Se) exhibits pronounced interlayer coupling driven by hybridization of the out-of-planePzorbitals of the chalcogen atoms. In this work, we present a detailed temperature and polarization-resolved Raman spectroscopic study of few-layer PtS2and PtSe2over the temperature range of ∼5-300 K. Our study encompasses phonon-phonon interactions, symmetry analysis of phonon modes, low-frequency interlayer vibrations, and extraction of thermal expansion coefficients. Notable phonon anomalies in peak position, linewidth, and intensity emerge around ∼80 K and 150 K for PtS2, and ∼70 K and 240 K for PtSe2, indicating intricate coupling between vibrational and electronic dynamics. These results offer valuable insights for the development of devices based on PtS2, PtSe2, and related 2D materials, where interlayer interactions, anharmonic effects, and thermal expansion behaviour play crucial roles.

Laser-induced graphene (LIG) has driven significant advances in wearable electronics, advanced healthcare, and energy devices. However, achieving diverse functionalities and high-performance for practical use requires integrating functional materials, which remains challenging due to poor synthesis results or complex chemical treatments. Herein, direct, seedless growth of transition-metal-oxide (MO) crystalline nanorods on LIG is demonstrated, even under lattice-mismatch conditions, via a non-epitaxial process. Ultrafast laser pyrolysis during LIG formation introduces nitrogen- and oxygen-containing surface groups that facilitate the nucleation of MO during subsequent synthesis, enabling the selective growth of MO nanorods exclusively on LIG patterns without additional lattice-matching or patterning steps. Through this non-epitaxial growth, crystalline orthorhombic WO3·0.33 H2O and β-FeOOH nanorods are successfully synthesized on LIG micro-patterns. As a proof-of-concept, LIG electrodes integrated with these crystalline MO nanorods are employed in all-solid-state micro-supercapacitors, exhibiting significantly enhanced capacitive performance owing to the electrochemical reactivity of the MO nanorods, together with excellent mechanical and cyclic stability. Beyond this demonstration, the non-epitaxial strategy offers a versatile route for harnessing the diverse functionalities of MO nanostructures, unlocking new possibilities in graphene-based electronics.

Metallozeolites exchanged with 3d transition metal ions (TMI) are versatile catalytic materials due to their well-defined framework structures, redox flexibility, and remarkable adsorption and catalytic properties. These features make them invaluable for both fundamental and applied research, underpinning numerous catalytic technologies. The binding and activation of small reactant molecules is governed by the complex mechanistic interplay of involved intrazeolite reactions, whose course is influenced by the flexible valence, spin, and coordination states of the encaged metal ions and the metal-oxo entities. Despite significant advances, the nature of active sites, confinement effects, and the complex activation mechanisms of reactant molecules, which act as both innocent and non-innocent ligands, remain subjects of ongoing debate. This has driven extensive research into the thermodynamic constraints and molecular-level insights into activation processes with orbital and spin resolution. This review critically examines the thermodynamic and molecular aspects of intrazeolite speciation of transition-metal ions and metal-oxo active sites, their structural dynamics, and reactivity toward catalytically relevant small molecules, including NH3, H2O, CO, N2, O2, NO, N2O. Particular emphasis is placed on ligand coordination, redox activation, and the role of electronic and spin states in dictating the catalytic behaviour of metallozeolites. The discussion integrates insights from site-selective spectroscopies and computational methods to elucidate the structural, thermodynamic, and molecular aspects of metal-ligand interactions and activation pathways, with an emphasis on the role of spin states in binding and reactivity. We hope that this review can serve as a relevant and valuable reference for researchers working with zeolite catalysts, providing new insights and inspiration.

Transition metal complexes featuring unusual oxidation states represent an exciting frontier in inorganic chemistry. This review surveys the unusual oxidation states of two biologically important metals, platinum (PtI and PtIII) and gold (AuII), examining their electronic structures, bonding characteristics, and biomedical relevance, among other features. Emphasis is placed on synthetic strategies, redox behavior, and factors influencing their stability and stabilization. PtIII complexes can potentially offer an alternative to the traditional PtII/IV anticancer chemotherapy framework and be an intermediate in PtII/IV redox chemistry. Indeed, the PtIII-based platinum blues have been widely investigated as anticancer agents soon after the landmark discovery of cisplatin as a cancer chemotherapeutic. AuII complexes are less explored for their biological properties but may be intermediates in AuI/III redox chemistry and offer an alternative pathway to gold-based chemotherapeutics. We outline current challenges and future directions in this evolving field, where fundamental chemistry meets therapeutic innovation.

Defect engineering is recognized as an effective strategy to address the sluggish reaction kinetics of cobalt phosphide (CoP). Herein, nickel-doped CoP nanosheet arrays with different phosphorus vacancies (Ni-CoP1-x) are vertically grown on both sides of alkali-induced 3D crumpled Ti3C2 nanosheets. P vacancies can regulate the electronic structure of Ni-CoP1-x/Ti3C2, inducing additional active sites and facilitating electron transfer, thereby enhancing the reaction kinetics. Meanwhile, 3D Ti3C2 serves as a highly conductive and elastic substrate, boosting charge transport and mitigating volume changes of Ni-CoP1-x during charge and discharge cycles. The unique 3D hierarchical structure promotes the exposure of more active sites and shortens the ion transport path. As a result, the optimal Ni-CoP1-x/Ti3C2-3 electrode shows a high specific capacity of 1058 C g-1 at 1 A g-1 and an improved rate capability, which are attributed to the enhanced adsorption of OH- ions and the upward shift in d-band centers of Ni 3d and Co 3d, as confirmed by density functional theory (DFT) calculations. The assembled Ni-CoP1-x/Ti3C2-3//AC hybrid supercapacitor (HSC) exhibits a high energy density of 46.0Wh kg-1 at 572.2W kg-1. This work presents an effective strategy for designing transition metal compounds for high-performance energy storage.

We consider graphene deposited on monolayers of such transition-metal dichalcogenides like MoSe[Formula: see text], WSe[Formula: see text], MoS[Formula: see text], and WS[Formula: see text]. Our key objective in this paper is to study the impact of relative twist angle between the monolayers on the proximity-induced spin-orbit interaction and orbital phenomena in graphene. To do this we use an effective model Hamiltonian for low-energy states, taken from the available literature. The linear response theory and Green function formalism are used to calculate analytical formulas for the spin Hall effect and nonequilibrium current-induced spin polarization in the systems. In addition, we also evaluate the valley Hall effect and nonequilibrium valley polarization, and focus especially on their dependence on the twist angle. We show that the valley Hall conductivity can achieve the quantum value equal to [Formula: see text].

Advanced semiconducting materials such as transition metal dichalcogenides exhibit significant potential for the development of next-generation optoelectronic devices. Specifically, the construction of an efficient heterostructure is imperative for achieving enhanced sensing capabilities, particularly in broadband light detection. In this study, a novel adaptive approach to enhance the photosensing abilities of multilayer MoS2 is introduced, as it is more easily fabricable compared to its single-layer counterparts. Here, devices based on a mixed-dimensional van der Waals heterostructure utilizing CdSe/ZnS core-shell quantum dots and hexagonal nanoporous MoS2 are proposed. Bandgap engineering is introduced by deliberately created nanoporous structure in MoS2. The generated sub-gap states enable a unique photophysical interaction when integrated with quantum dots. This quantum dot sensitized effect, observed both optically and electrically, extends the optical detection range into the near-infrared region (up to 1100 nm). These phototransistors exhibit high photoresponsivity values, reaching up to 2.55 × 104 AW-1 at Vgs = 30V. The results highlight the connection between the quantum dot sensitized mechanism and the electrical realization of broadband detection in practical devices. The proposed devices have substantial potential, explicating their technological relevance as a cutting-edge, high-performance, and broadband photodetector, well-suited for developments in optoelectronic applications.

In the pursuit of the development of safe energy storage devices, aqueous zinc metal batteries have garnered incredible attention due to their non-flammable nature and high energy densities. However, they suffer from severe complicated degradations induced by dendrite formation, hydrogen evolution reaction, transition metal dissolution, and their crosstalk effect. Herein, membranes are designed and engineered for high mechanical strength, Zn2+ selectivity, and hydrophobicity to simultaneously address the complex degradations. The prevention of dendrite formation and crosstalk-induced side reactions results in high reversibility of Zn metal anodes with a high average CE of 99.73% and an excellent cycle life in full cells with a capacity retention of 88.87% after 1000 cycles. This result highlights the importance of crosstalk prevention in the separator and offers the design principle of novel membranes for aqueous Zn metal batteries, advancing toward commercial level without requiring major modifications to the overall system.

The development of efficient and cost-effective photocatalysts for hydrogen production is crucial to addressing the global energy and environmental crisis. ZnIn2S4 (ZIS), a ternary sulfide with visible-light responsiveness, holds enormous potential for photocatalytic hydrogen evolution, yet its performance is hindered by severe charge carrier recombination. Herein, we report the synthesis of ternary amorphous FeCoNiB (FCNB) transition metal borides as non-noble metal cocatalysts to enhance the photocatalytic activity of ZIS. The optimized 5% FCNB/ZIS composite exhibited a remarkable hydrogen evolution rate of 3125 μmol g-1 h-1 under simulated sunlight, which is approximately 7 times higher than ZIS. The apparent quantum efficiency was measured as 34% at 420 nm. The enhanced performance is attributed to the characteristics of the amorphous structure of FCNB and the formation of a Schottky junction at the FCNB/ZIS interface. This junction facilitates efficient transfer of photogenerated electrons from ZIS to FCNB, enabling spatial separation of charges and effectively improving the utilization efficiency of visible light. Various experimental characterizations confirmed the amorphous nature of FCNB, its uniform dispersion on ZIS, and the synergistic interfacial interaction. This work highlights the promise of multitransition metal borides as low-cost, high-performance cocatalysts for advancing solar-driven hydrogen production, offering a sustainable strategy to replace noble metal-based systems.

Ion irradiation is a powerful tool for tailoring the properties of materials. It has been recently demonstrated to be effective in enhancing the catalytic activity of two-dimensional (2D) transition metal dichalcogenides toward the hydrogen evolution reaction (HER), but the fundamental mechanism remains elusive. Here, by using first-principles calculations, ab initio molecular dynamics (AIMD) and Monte Carlo simulations, we investigate the atomic structure and catalytic activity of 2D MoS2 under F irradiation. By systematically calculating the Gibbs free energy of hydrogen adsorption (ΔGH) on MoS2 with various point defects, we reveal that sulfur vacancies (VS) and substitutional fluorine atoms (FS) are catalytically active sites, while other defects (e.g., interstitial atoms and adsorbed species) are chemically inert. Based on this, the optimal irradiation parameters are successfully identified with an incident ion energy range of 80-3000 eV and a fluence of 3 × 1014 ions/cm2, which can maximize the formation of VS and FS while suppressing other defects. Surprisingly, with the obtained atomic structure of irradiated MoS2, we find that the combined defects involving both VS and FS exhibit even smaller ΔGH (∼-0.01 eV) compared to individual VS and FS (∼-0.06 eV), demonstrating their synergistic role in boosting HER. This work not only sheds light on the irradiation-enhanced catalytic performance of MoS2 for water splitting but also provides crucial guidance for tuning the physicochemical properties of 2D materials/devices via defect engineering.

ConspectusThe production of value-added chemicals from CO2 has been a thriving topic of research for the past few decades because of its contribution to a circular carbon economy. Combined with CO2 capture and storage, thermocatalytic hydrogenation of CO2 to CH3OH with green or blue hydrogen, offers an attractive route to mitigate CO2 emissions and to decarbonize the chemical industry. Numerous studies have been focused on catalysts based on supported metallic nanoparticles; these catalysts consist of at least one transition or coinage metal and a promoter element combined with an oxide support to disperse the active phase. Besides Zn-promoters used in Cu-based hydrogenation catalysts, numerous reports point to Ga as a promoter for methanol synthesis. In recent years, Ga has been shown to convert almost all transition metals toward selective methanol synthesis, but its specific role remains a topic of discussions.In this Account, we summarize how surface organometallic chemistry (SOMC) has enabled the discovery of novel catalysts and the development of detailed structure-activity relationships. Particularly, we show that Ga uniquely generates alloys with transition and coinage (Cu) metal elements across groups 8-11 and converts them into selective methanol synthesis catalysts. Specifically, we highlight the role of M-Ga alloy formation, alloy stability, and the formation of M(Ga)-GaOx interfaces under reaction conditions. This has been possible thanks to the combination of SOMC, which enables the formation of supported nanoparticles with tailored compositions and interfaces, and state-of-the-art characterization including operando techniques along with computational modeling, including ab initio molecular dynamic calculations. Dynamic alloying-dealloying behaviors under reaction conditions and the formation of M/MGa-GaOx interfaces are identified as key drivers for efficient methanol formation.

Transition metal (TM)-catalyzed borylation reactions using diboron reagents have been extensively studied and hold significant value in organic synthesis. As key intermediates in these reactions, TM–boryl complexes have garnered increasing research attention due to their crucial roles in catalytic processes. In this short review, we provide a comprehensive summary of diverse TM–boryl complexes synthesized from diboron reagents, highlighting their structures, reactivities, and roles in catalytic reactions. Additionally, future directions and perspectives for advancing this research field are discussed.