Metal-like Properties Research Articles

COMPARATIVE EVALUATION OF SHEAR BOND STRENGTH OF TWO DIFFERENT RESIN CEMENT TO ZIRCONIA AFTER SURFACE TREATMENT USING ER:YAG LASER: AN IN VITRO STUDY

Zirconia (ZrO2), a crystalline dioxide of zirconium, boasts metal-like mechanical properties and a tooth-like color. Creating a ZrO2 core for prosthetic restorations necessitates a CAD/CAM system adept at handling zirconia. Resin-bonded luting is the top choice for zirconia ceramic restorations, with tribochemical treatment preferred for surface preparation before resin cement luting. Clinical trials indicate that resin cementation improves adhesion and mechanical properties of zirconia restorations. While studies on sandblastings effect on shear bond strength to zirconia exist, more data is needed on the impact of sandblasting and laser treatment on yttria-stabilized tetragonal zirconia. This study examines the shear bond strength of two resin cements to zirconia after Er:YAG laser treatment.

Single-Atom Catalysts with p-Block Metals Surpass Transition-Metal Counterparts in the Photocatalytic H2O2 Production.

Growing interest in p-block metal single-atom catalysts (PM-SACs) is driven by their low toxicity, economic viability, and transition metal-like catalytic properties. However, selection criteria for p-block single-atom species and catalytic mechanisms of PM-SACs remain unclear. This study explores the catalytic abilities of PM-SACs and their transition metal counterparts (TM-SACs) based on polymetric carbon nitride (PCN) for photocatalytic hydrogen peroxide (H2O2) production. Using thermodynamic barriers as a key descriptor, it was found that PM-SACs can surpass TM-SACs in H2O2 production due to a lower energy barrier for *OOH intermediate formation resulting from optimized p-p hybridization. Specifically, Sb-SAC based on PCN shows the highest apparent quantum yield of 35.3 % at 400 nm. This study offers a rationale for the utilization of p-block SACs in the context of sustainable chemical synthesis.

Novel cocatalyst MnCo2S4 based on Zn3In2S6 for enhanced photocatalytic hydrogen production and ranitidine degradation

Photocatalysis offers a sustainable method for producing hydrogen and degrading harmful substances such as ranitidine. In this research, metal-like properties of MnCo2S4 nanoparticles were synthesized using a glycerol precursor and integrated into Zn3In2S6 floral microsphere via a low-temperature hydrothermal method to function effectively as a cocatalyst. The catalyst not only exhibits excellent hydrogen production efficiency but also demonstrates outstanding performance in degrading ranitidine. Under visible light irradiation, the MnCo2S4/Zn3In2S6 composite material reached a maximum hydrogen production rate of 4471.7 µmol·g−1·h−1 within 6 h, which is 10.6 times higher than that of pure Zn3In2S6. After 24 h of reaction over 4 continuous cycles, the hydrogen evolution activity maintained 94.86 % of its initial performance. Additionally, after 60 min of visible light exposure, the composite achieved a ranitidine degradation rate of 94.7 %, significantly surpassing the performance of pure Zn3In2S6. This exceptional photocatalytic activity is attributed to the synergistic interactions between Zn3In2S6 and the conductive cocatalyst MnCo2S4, which facilitate interfacial charge transfer. A potential reaction mechanism was proposed, supported by a series of experiments and characterization techniques. The formation of a Schottky junction at the MnCo2S4/Zn3In2S6 interface enables rapid electron transfer to the MnCo2S4 nanoparticles, preventing electron backflow and thus promoting effective separation of photo-induced charge carriers. Therefore, this study introduces a novel approach for designing metal-semiconductor photocatalysts for efficient hydrogen production and ranitidine degradation.

Tailoring and understanding the lithium storage performance of triple-doped cobalt phosphide composites

Cobalt phosphide (CoP) with high theoretical capacity as well as ceramic-like and metal-like properties is considered as a promising anode for lithium-ion batteries (LIBs). However, the large volume change and sluggish kinetic response limit its practical application. The optimization of composition, structural control and performance regulation of CoP electrodes can be achieved by the bottom-up assembly technique of metal–organic frameworks (MOFs). Due to the effective electronic regulation and lithiophilicity brought by the multiple heteroatoms doping and the synergistic effect of the unique structure derived from MOFs, the N, O, P triple-doped carbon and CoP composites (ZCP@NOP) exhibited excellent rate capability (554.61 mAh g−1 at 2 A g−1) and cycling stability (806.7 mAh g−1 after 500 cycles at 0.5 A g−1). The essence and evolution of lithium storage mechanism in CoP electrodes are also confirmed by the ex-situ techniques. The synergistic benefits of heteroatom co-doping carbon and cobalt phosphide, such as the decrease of the diffusion energy barrier of Li-ions and the optimization of electronic structures, are highlighted in theoretical calculations. In conclusion, new thoughts and ideas for the creation of future battery anode are provided by the combination of the N, O, P co-doping and the adaptable structural adjustment technique.

Recent Progress of Transition Metal Selenides for Electrochemical Oxygen Reduction to Hydrogen Peroxide: From Catalyst Design to Electrolyzers Application.

Hydrogen peroxide (H2O2) is a highly value-added and environmental-friendly chemical with various applications. The production of H2O2 by electrocatalytic 2e- oxygen reduction reaction (ORR) has emerged as a promising alternative to the energy-intensive anthraquinone process. High selectivity Catalysts combining with superior activity are critical for the efficient electrosynthesis of H2O2. Earth-abundant transition metal selenides (TMSs) being discovered as a classic of stable, low-cost, highly active and selective catalysts for electrochemical 2e- ORR. These features come from the relatively large atomic radius of selenium element, the metal-like properties and the abundant reserves. Moreover, compared with the advanced noble metal or single-atom catalysts, the kinetic current density of TMSs for H2O2 generation is higher in acidic solution, which enable them to become suitable catalyst candidates. Herein, the recent progress of TMSs for ORR to H2O2 is systematically reviewed. The effects of TMSs electrocatalysts on the activity, selectivity and stability of ORR to H2O2 are summarized. It is intended to provide an insight from catalyst design and corresponding reaction mechanisms to the device setup, and to discuss the relationship between structure and activity.

NiCo-MOFs in situ anchored on graphdiyne with metal-like properties form a strongly coupled electron transport interface and construct an ohmic contact to achieve efficient charge-hole spatial separation.

Metals exhibit unique characteristics in photocatalysis, and their incorporation into semiconductors can result in remarkable features. This study focuses on the preparation of graphdiyne with Cu (CG) by using Cu powder as a catalyst. The addition of Cu reduces the narrow band gap of graphdiyne and imparts metal-like properties to the material. By leveraging the electronegativity of CG, a spherical NiCo-MOF (NC) is grown and in situ anchored on CG, forming a strongly coupled electron transport interface. In addition, the CG with metal-like properties also displays distinct characteristics. The integration of CG and NC through an ohmic contact significantly enhances the spatial separation of photogenerated carrier holes. Efficient hydrogen evolution is achieved through a synergistic effect of the strongly coupled electron transport interface and the spatial separation of photogenerated carrier holes. This research provides a new perspective on the design and development of metal-like narrow band gap semiconductors.

Full-spectrum plasmonic semiconductors for photocatalysis.

Localized surface plasmon resonance (LSPR) of noble metal nanoparticles can focus surrounding light onto the particle surface to boost photochemical reactions and solar energy utilization. However, the rarity and high cost of noble metals limit their applications in plasmonic photocatalysis, forcing researchers to seek low-cost alternatives. Recently, some heavily doped semiconductors with high free carrier density have garnered attention due to their metal-like LSPR properties. However, plasmonic semiconductors have complex surface structures characterized by the presence of a depletion layer, which poses challenges for active site exposure and hot carrier transfer, resulting in low photocatalytic activity. In this review, we introduce the essential characteristics and types, synthesis methods, and characterization techniques of full-spectrum plasmonic semiconductors, elucidate the mechanism of full-spectrum nonmetallic plasmonic photocatalysis, including the local electromagnetic field, hot carrier generation and transfer, the photothermal effect, and the solutions for the surface depletion layer, and summarize the applications of plasmonic semiconductors in photocatalytic environmental remediation, CO2 reduction, H2 generation, and organic transformations. Finally, we provide a perspective on full-spectrum plasmonic photocatalysis, aiming to guide the design and development of plasmonic photocatalysts.

Constructing plasmonic electron acceptors on TiO2 for full-spectrum-driven photocatalytic hydrogen generation

W-doped TiO2 nanodots (WTO-NDs) as plasmonic electron acceptors were controllably grown on TiO2 nanosheets (TO-NSs) to construct a plasmonic isotype heterostructure of WTO-NDs/TO-NSs for full-spectrum-driven photocatalytic hydrogen evolution.

The Effects of Chlorine Doping on the Mechanical Properties of Bi2O2Se

In this work, first-principle calculations based on density functional theory are employed to investigate how chlorine doping influences the elastic moduli, ductility, and lattice thermal conductivity of Bi2O2Se, aiming to explore an effective method to improve its mechanical properties for its applications under thermal stress. Our findings reveal that chlorine(Cl) doping significantly affects the electronic structure and mechanical properties of Bi2O2Se. The electrons are distributed on the Fermi level, and the Cl-doped Bi2O2Se exhibits metal-like properties. In addition, Cl doping enhances the ductility and toughness of Bi2O2Se and reduces its lattice thermal conductivity. These results suggest that Cl doping is an effective approach for tuning the mechanical properties of Bi2O2Se.

Rational Construction of Electrostatic Self‐Assembly of Metallike MoP and ZnIn2S4 Based on Density Functional Theory to Form Schottky Junction for Photocatalytic Hydrogen Production

It is an effective strategy to construct a photogenerated carrier‐transfer channel based on the load between photocatalysts to improve the light‐absorption capacity and separation efficiency of a single photocatalyst. In this work, the MoP is embedded on the surface of ZnIn2S4 through electrostatic self‐assembly to form ZnIn2S4/MoP‐20%, the hydrogen production performance is 151.93 μmol in 5 h, and is 13 times that of ZnIn2S4, which greatly improves the hydrogen production performance of ZnIn2S4. Based on density functional theory (DFT) calculation, MoP with metallike properties and semiconductor ZnIn2S4 with indirect bandgap successfully constructed Schottky junction. MoP acts as the active site in hydrogen production system and accepts photogenerated electrons through Schottky junction, which can effectively accelerate the separation of electron–hole pairs and enable more effective photogenerated electrons to participate in photocatalytic hydrogen production reaction. In this experiment, a new method is provided for the development of Schottky junction based on DFT calculation to efficiently use solar photocatalytic water to produce hydrogen.

Cellulose-based bioabsorbable and antibiotic coated surgical staple with bioinspired design for efficient wound closure

The quest to design a flawless wound closure system began long ago and is still underway. Introducing surgical staples is one of the most significant breakthroughs in this effort. In this work, we developed a biodegradable surgical staple to meet the optimal wound closure system criteria and other clinical requirements, such as radiography compatibility and secondary infection prevention. To meet these requirements, a naturally derived cellulose acetate (CA) fiber-reinforced poly-(l-lactic acid) (PLLA) composite was synthesized, and its physicochemical properties were determined using several characterizations such as Fourier-transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC) and Universal testing machine (UTM), etc. Taking cues from the Mantis's foreleg, a novel staple design was implemented and verified using Finite Element Analysis (FEA). The CA + PLLA staples were fabricated using melt-casted/3D-printing processes. The staples exhibited excellent biodegradation in both wound and physiological microenvironments with sufficient puncturing strength and later closed the wound's edges mechanically. In addition, the CA + PLLA staples also exhibit metal-like ductility properties to withstand horizontal skin tensions during the healing process. Further, the staples are coated with an antibiotic to combat infections effectively to provide better healing.

High Performance GaN-Based Ultraviolet Photodetector via Te/Metal Electrodes.

Photodetectors (PDs) based on two-dimensional (2D) materials have promising applications in modern electronics and optoelectronics. However, due to the intralayer recombination of the photogenerated carriers and the inevitable surface trapping stages of the constituent layers, the PDs based on 2D materials usually suffer from low responsivity and poor response speed. In this work, a distinguished GaN-based photodetector is constructed on a sapphire substrate with Te/metal electrodes. Due to the metal-like properties of tellurium, the band bending at the interface between Te and GaN generates an inherent electric field, which greatly reduces the carrier transport barrier and promotes the photoresponse of GaN. This Te-enhanced GaN-based PD show a promising responsivity of 4951 mA/W, detectivity of 1.79 × 1014 Jones, and an external quantum efficiency of 169%. In addition, owing to the collection efficiency of carriers by this Te-GaN interface, the response time is greatly decreased compared with pure GaN PDs. This high performance can be attributed to the fact that Te reduces the contact resistance of the metal electrode Au/Ti to GaN, forming an ohmic-like contact and promoting the photoresponse of GaN. This work greatly extends the application potential of GaN in the field of high-performance photodetectors and puts forward a new way of developing high performance photodetectors.

Dual-Doping Strategy for Enhancing Hydrogen Evolution on Molybdenum Carbide Catalysts

Hydrogen evolution reaction (HER) is a topic of great interest due to its efficient hydrogen production properties, which can address the increasing demand for clean and sustainable energy sources. On the other hand, molybdenum carbide (MoC) has been widely studied due to its noble metal-like surface electronic properties. In the HER process, it is crucial to regulate the Mo−H bonding energy effectively and increase the electron transfer rate on the MoC catalyst surface in a rational manner. In this study, we introduce highly electronegative nitrogen and non-noble transition metal atoms (Cu or Co) into the molybdenum carbide crystal lattice (N−M−MoC, M: Cu, or Co), which leads to a dual—doping effect. This effect results in the rearrangement of the electronic configuration on the catalyst surface and the enrichment of electrons around Mo atom, leading to an optimization in the Mo−H bonding energy. Moreover, the unique two-dimensional nano-sheet structure of the N−M−MoC materials further promotes the electron transfer and exposure of active sites. Benefiting from the above, the HER performance of the N−M−MoC is significantly improved. Among them, N−Cu−MoC exhibits the lowest overpotential (η10 = 158 mV) and highest stability (about 30 h) in alkaline solutions.

ThIrGe superconductor: First-principles insights into the optoelectronic, mechanical stability, thermophysical, and superconducting properties

The structural, electronic, optical, elastic, vibrational, Vickers hardness, and thermophysical properties of the ThIrGe superconductor are given. The characteristics of this technologically important superconductor are computed using the CASTEP formulation, based on density functional theory. The computed physical properties of ThIrGe are compared to available data and demonstrate good agreement. The band structure of this compound exhibits metal-like properties as the valence and conduction bands overlap at the Fermi level. The reflectance spectrum indicates that this material has potential as an effective solar reflector. Under Born stability conditions, the compound is mechanically stable. Different anisotropic parameters provide information about anisotropic properties in various crystallographic directions. Vickers hardness demonstrates that ThIrGe is soft, and Pugh's, Poisson's, and Kleinman's parameters show that it is ductile. The anisotropic acoustic modes are also reported. Using present elastic constants data, the theoretical Debye temperature of ThIrGe is 235.85 K. The electron–phonon coupling parameter is used to calculate superconducting properties. The findings could provide a useful foundation for scientists and engineers.

Conductometric NO2 gas sensors achieved by design of Ti3C2Tx @ZnO heterostructures for application around 80 °C

Low-temperature, stable and highly selective behaviors are the essential indicators for evaluating gas sensors. Although ZnO has attractive stability as a sensitive material, it is still an enormous challenge to construct highly sensitive gas sensors with high selectivity at low temperatures employing ZnO. Herein, we have achieved a high-selectivity and low-temperature stable nitrogen dioxide (NO2) gas sensor by composite of Ti3C2Tx flakes with ZnO nanorods by facile hydrothermal process. As a results, Ti3C2Tx doped with 3 mmol ZnO exhibits the highest sensitivity (190%, 50 ppm), outstanding selectivity and stability for NO2 gas, due to the presence of multiple Schottky barriers (SB), which are originated from the heterostructure of Ti3C2Tx and ZnO. The metal-like properties of Ti3C2Tx can provide multiple electron transfer channels and accelerate the electron transfer rate. Moreover, the adsorption of more NO2 molecules can also enhance the sensitivity of sensitive material as ZnO, which is rich in adsorption sites, can form interactions with NO2. The first-principles calculation supported a preferential adsorption of NO2 on ZnO nanorods. Our investigation facilitates the appropriate design of high-performance gas sensors at lower operating temperature.

CoP decorated SnS2 nanosheets with synergistic electronic and electrocatalysis sensitization for enhanced room temperature NO2 sensing

Due to the metal-like property and high catalytic activity, CoP material has been regarded as a potential noble metal alternative in gas sensing area. Herein, CoP decorated SnS2 nanosheets were successfully synthesized via an ultrasonic assisted physical combination method. Structure characterizations indicated the ultrasmall sizes and uniform distributions of CoP nanoparticles on SnS2 nanosheet surface. Gas sensing results showed that the SP-3 sensors (mass ratio: CoP/SnS2 =1:3) possessed much higher sensing response (80 %@10 ppm) to NO2 gas at room temperature (RT, 25 °C) than pristine SnS2 (nearly no response) and 5 % Pt modified SnS2 (57.4 %@10 ppm), indicating a better sensitization effect of CoP than Pt nanoparticles. Arrhenius equation fitting results showed that CoP mainly enhanced the NO2 sensing behavior by electronic sensitization via constructing heterojunctions with SnS2. Moreover, the NO2 sensing response of SP-3 sensors also increased with adding trace water molecules, contradict to the response curve versus increasing relative humidity, due to the dynamic equilibrium between electrocatalytic water splitting facilitated surface NO2 adsorptions and over-adsorption of water vapors hindered NO2 adsorptions. This work highlights the important role of CoP in gas sensing, which will also promote the exploration and understanding of novel materials to replace noble metal.

Perfect absorption based on Ti3C2Tx surface plasmon resonance

As a kind of emerging two-dimensional material, Ti3C2Tx possesses metal-like property, which can be utilized to generate strong surface plasmon resonance in optical regime. In this paper, a perfect metamaterial absorber (BPMA) is proposed, which consists of the top Ti3C2Tx layer, the middle SiO2 layer and the bottom gold layer. The BPMA with the simple structure can achieve perfect (near-unity) absorption ranging from 693 nm to 897 nm. The electric field distribution reveals that the perfect absorption in this wavelength range is attributed to localized surface plasmon resonance produced by Ti3C2Tx. Furthermore, the perfect absorption exhibits good stability to polarization and incident angles. The calculated absorptivity based on interference theory agrees well with the simulation result, thereby demonstrating the design. This work provides a simple method to achieve perfect absorption across a wavelength range in visible and near-infrared regions.

Ti3C2 MXene improved photoelectrochemical anode assembly of titanium dioxide nanoarrays for microcystin-LR detection.

MXenes with metal-like properties in the improvement of band gap and drive off photon-generated carrier transport have become one of the most promising co-catalysts. However, their unavoidable two-dimensional morphology limits their applications in sensing because this emphasizes the well-ordered microstructure of signal label to trigger stable signal output. In this work, a photoelectrochemical (PEC) aptasensor utilizing titanium dioxide nanoarrays/Ti3C2 MXene (TiO2/Ti3C2) composites as an anode current generator is proposed. Conventional, TiO2 generated by in situ oxidation of Ti3C2 was replaced with physically pulverized Ti3C2 and uniformly inlaid on the rutile TiO2 NAs surface by an ordered self-assembly. This method results in high consistency in morphology and exhibits a stable photocurrent output when detecting microcystin-LR (MC-LR), the most dangerous toxin in water. We believe that this study is a promising approach for sensing carrier preparation and significant target detection.

Homovalent cationic Se dopant with noble metal-like activation properties to enhance the sensitivity of SnO2 sensors

A challenge for low-valence cation doping in SnO2 materials is that the sharply elevated baseline resistance is detrimental to sensor stability and the subsequent signal acquisition. In contrast, Homovalent doping has little effect on resistance but the effective homovalent dopant is few. Herein, we find the non-metallic element Se is prone to form cationic SeSn defects in SnO2, which can improve the sensitivity of the SnO2-based sensors with a moderate rise in baseline resistance. The homovalent Se doping make the species and ratio of adsorbed oxygen on Se-doped SnO2 surface basically unchanged after doping. Further experiments and theoretical calculations confirm the sensitization mechanism of Se-doped SnO2 can be attributed to the higher activity of adsorbed oxygen on its surface. Therefore, the sensor based on Se-doped SnO2 can have sufficient sensing-reactions and charge transfer at a temperature close to the maximum value of the baseline resistance, which makes the sensor better to sensitize the target gases requiring high temperature for sensing-reactions. This noble metal-like activation behavior of Se dopant is derived from the easier breaking of Se-O bond compared to Sn-O bond during CO oxidation which provides a new basis for the selection of dopants from the perspective of bond energy.

Metal-like Charge Transport in PEDOT(OH) Films by Post-processing Side Chain Removal from a Soluble Precursor Polymer.

Herein, a route to produce highly electrically conductive doped hydroxymethyl functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) films, termed PEDOT(OH) with metal-like charge transport properties using a fully solution processable precursor polymer is reported. This is achieved via an ester-functionalized PEDOT derivative [PEDOT(EHE)] that is soluble in a range of solvents with excellent film-forming ability. PEDOT(EHE) demonstrates moderate electrical conductivities of 20-60 S cm-1 and hopping-like (i.e., thermally activated) transport when doped with ferric tosylate (FeTos3 ). Upon basic hydrolysis of PEDOT(EHE) films, the electrically insulative side chains are cleaved and washed from the polymer film, leaving a densified film of PEDOT(OH). These films, when optimally doped, reach electrical conductivities of ≈1200 S cm-1 and demonstrate metal-like (i.e., thermally deactivated and band-like) transport properties and high stability at comparable doping levels.