There has been emerging interest in the exploitation of the photophysical and photochemical properties of transition metal complexes for diagnostic and therapeutic applications. In this Perspective, ...we highlight the major recent advances in the development of luminescent and photofunctional transition metal complexes, in particular, those of rhenium(I), ruthenium(II), osmium(II), iridium(III), and platinum(II), as bioimaging reagents and phototherapeutic agents, with a focus on the molecular design strategies that harness and modulate the interesting photophysical and photochemical behavior of the complexes. We also discuss the current challenges and future outlook of transition metal complexes for both fundamental research and clinical applications.
High‐entropy oxides (HEOs), a class of newly emerging energy conversion and storage technology materials, have gained significant interest due to their unique structure, complex stoichiometry, and ...corresponding synergetic effect. Despite the increasing number of reported studies related to HEOs in recent years, details of their structural properties and electrochemical activities are still lacking. Herein, the exciting developments of HEOs regarding their design, synthesis, characterization, theoretical calculations, and electrochemical performances are outlined. The fundamentals of HEOs, including their strict definition, main features, and four‐core aspect effects are presented. The different synthetic methods of HEOs are categorized to highlight the significance of parameter optimization to ensure the single‐phase stability of HEOs. The advances in characterization techniques on the local lattice and atomic distribution and the basic principles of combinatorial screening methods based on computational techniques are also elaborated. Recent HEO‐based electrode/electrocatalysts toward Li‐ion batteries and oxygen catalysis are reviewed to assess the potential applications of HEOs. This review draws attention to the critical challenges of HEOs that are worth more extensive explorations in the future.
This review unravels the exciting developments of high‐entropy oxides. A direct connection between the unique structural properties of high‐entropy oxides and their remarkable electrochemical activities toward energy storage and conversion systems is established.
Glucose electrooxidation is of particular interest owing to its broad applications in glucose fuel cell and electrochemical sensing. In pursuit of high atomic utilization of catalytic active sites, ...we employed homogenously dispersed transition metal ions (Co2+, Cu2+, and Ni2+) as the electrocatalyst in alkaline electrolyte. Combining cyclic voltammetry, chronoamperometry, impedance spectroscopy, and in situ UV–Vis spectroelectrochemistry, the catalytic activity and reaction mechanism of M(II)-catalyzed glucose electrooxidation are discussed, suggesting a general activity trend of Co(II) > Cu(II) > Ni(II). Using a μM level of Co(II), Cu(II), and Ni(II), the sensitivity values of 1,342, 579, and 38.9 mA M−1 cm−2 are achieved, respectively, toward glucose sensing. The coordination between metal sites and glucose plays the critical role of lowing the oxidation potential of M(II) to higher valent forms. A homogenous reaction mechanism is suggested: Co(II)-catalyzed reaction shows potential-dependent electrooxidation via the formation of Co(III)-glucose and Co(IV)-glucose complex, while both Cu(II) and Ni(II) feature the intermediate of M(III)-glucose. The Co(II)-glucose electrooxidation presents the smallest charge transfer resistance and the highest transfer coefficient, accounting for its high activity.
Display omitted
2D titanium carbide (Ti3C2Tx MXene) is recognized as a promising material for pseudocapacitor electrodes in acidic solutions, while the current studies in neutral electrolytes show much poorer ...performances. By a simple hydrothermal method, vanadium‐doped Ti3C2Tx 2D nanosheets are prepared to tune the interaction between MXene and alkali metal adsorbates (Li+, Na+, and K+) in the neutral electrolyte. Maintaining the 2D morphology of MXene, the coexisting V3+ and V4+ are confirmed to form surface V–C and V–O species. At a medium doping level of V:Ti = 0.17:1, the V‐doped MXene exhibits the highest capacitance of 365.9 F g−1 in 2 m KCl (10 mV s−1) and excellent stability (5% loss after 5000 cycles), compared to only 115.7 F g−1 of pristine MXene. Density functional theory calculations reveal the stronger alkali metal ion–O interaction on V‐doped MXene surface than unmodified MXene and a further capacitance boost to 404.9 F g−1 using Li+‐containing neutral electrolyte is reported, which is comparable to the performance under acidic conditions.
Vanadium‐doped titanium carbide (Ti3C2Tx
MXene) nanosheets are prepared via a simple hydrothermal method to tune the interaction between MXene and alkali metal adsorbates (Li+, Na+, and K+) in neutral electrolytes. The strong alkali metal ion–O interaction on the V‐doped MXene surface boosts the capacitance to 404.9 F g−1, which is comparable to the performance under acidic conditions.
•A new non-enzyme glucose sensing system is developed using carbon material-modified electrode and Cu2+ ion.•It is demonstrated to show high sensitivity (2,149 mA M−1 cm−2 on carbon paper), low ...detection limit, large linear range, and high stability.•The sensitivity and linear range can be tuned by the applied potential, Cu2+ concentration, and carbon material type.•By anchoring nanomolar Cu2+ ions on the carbon support, a practical glucose sensor of ultra-high sensitive (1,732 mA M−1 cm−2) is demonstrated.
Nearly all current non-enzymatic electrochemical glucose sensors involve carefully designed metal/metal oxide nanomaterials and the complications of preparing electrocatalyst increase the fabrication cost and reduce the reproducibility of a sensor. Thus, a simple yet reliable and cost-effective glucose sensing system is much desired. Inspired by the glucose oxidation mechanism of copper-based nanomaterials, we developed a series of highly sensitive electrochemical glucose sensors using micromol level Cu2+ ions as an electrocatalyst. High sensitivities are achieved on various carbon-based electrodes (GCE: 614 mA M−1 cm−2; activated carbon: 1627 mA M−1 cm−2; carbon paper: 2149 mA M−1 cm−2; graphite powder: 1695 mA M−1 cm−2, and functionalized multi-walled carbon nanotube: 1842 mA M−1 cm−2). With short response time (<2 s), large linear range (0.02 μM–2.5 mM and 2.5–8.0 mM), high stability, and excellent tolerance to interference, Cu ion-based sensor was also validated for testing glucose level in real blood samples. Further studies show that carbon support (e.g., MWCNT-COOH) can be doped with nanomolar level Cu2+ to produce a practical solid electrode with an ultra-high sensitivity of 1732 mA M−1 cm−2, retaining the advantage of atomic efficiency. This work provides a new route to the rational design of simple, cheap, and highly effective electrochemical glucose sensors.
Despite decades of attempts to reveal its flaws, the Standard Model of particle physics (SM) has withstood all experimental tests and its predictions are in excellent agreement with data. Since the ...theory was formulated, experiments have provided little guidance regarding the explanations of phenomena not described by the SM, such as the baryon asymmetry of the universe and dark matter. Nor do we have satisfying understanding of the aesthetic and theoretical problems of the model, despite years of searching for new processes and particles proposed to solve them. Such particles can evade being discovered by the comprehensive search programs at collider experiments if the analysis selections and the algorithms used to reconstruct the detector data are not matched to the characteristics of the particles, e.g. if they have long enough lifetimes. As interest in searches for such long-lived particles at colliders grows rapidly, we present a review of this area of research in this article. The broad range of theoretical motivations for particles with long lifetimes and the experimental strategies and methods employed to search for them are described. Results from decades of searches are reviewed, as are opportunities for the next generation of searches both at existing and proposed future experiments.
Polymeric metal phthalocyanines have great potential as electrocatalysts, yet their incorporation on a current collector without losing the activity of metal centers remains a challenge. Herein, a ...new strategy for preparing a series of polymeric cobalt phthalocyanines containing S linkers (pCoPc‐1) or SO2 linkers (pCoPc‐2) and their tunable electrochemical properties are reported. The pCoPcs coated on various substrates show favorable electrocatalytic activities toward oxygen and hydrogen evolution reactions (OER and HER). Particularly, the pCoPc‐1 layer on Co3O4 nanosheet arrays exerts a cooperative effect enhancing both the OER and HER performances, and the subsequent phosphorization (P@pCoPc‐1/Co3O4|CC) significantly boosts the HER performance with enhanced hydrophilicity and conductivity. The high permeability and stability reinforcement of the pCoPc‐1 layer allow the phosphorization of underlying Co3O4 to CoP without degradation, which remarkably enhances OER and HER performances as manifested by low overpotentials of 320 and 120 mV at 10 mA cm−2, respectively. When engaged as a bifunctional electrocatalyst for the overall water splitting, the P@pCoPc‐1/Co3O4|CC requires a low cell voltage of 1.672 V at 10 mA cm−2, showing long‐term durability and mechanical robustness. This study demonstrates the collaborative catalytic role of polymeric macrocyclic compounds that offers versatile tunability and stability for various electrocatalytic reactions.
The polymeric cobalt phthalocyanines containing S linkers (pCoPc‐S) allow the partial phosphorization of underlying Co3O4 nanoarrays on carbon cloth to CoP (P@pCoPc‐S/Co3O4|CC), enabling remarkably enhanced catalytic performances toward oxygen and hydrogen evolution reactions. This improvement is ascribed to the modified electronic structure by S‐linker, enhanced hydrophilicity and conductivity, and cooperative catalytic effect due to the excellent permeability of the pCoPc‐S.
PDF