Search

Abstract: Carbon black, a black material popular for use in electronic paper, could limit the performance of the electronic paper due to its non-uniform structure. Carbon spheres, with spherical shape and relatively narrow size distribution, are expected to overcome this limitation and substitute for carbon black in the electronic paper. Carbon spheres were synthesized through a hydrothermal reaction using glucose as a raw material. By controlling reaction time and glucose concentration, appropriate non-agglomerated carbon spheres with an average diameter of 202.26 (±26.15) nm were fabricated. To increase their dispersibility in dielectric fluid, p-(2-ethylhexyl acrylate) was grafted onto the surface of the carbon spheres. Then, acid and base charge control agents were mixed with the carbon spheres to produce a pigment with higher mobility in the dielectric fluid. The optimized combination of pigment, charge control agent and solvent reveals reasonably fast switching time of about 540 ms. [Copyright &y& Elsevier]

Abstract: Femtosecond white-light continuum probe transient absorption and reflectivity measurements of bulk graphite and graphene paper are reported. In graphite, the relaxation of photoinduced electron–hole pairs happens through in-plane electron–electron and electron–phonon scattering in ≃200fs, while the ps dynamics is due to the modulation of the electronic structure by out-of-plane structural motions. The ps dynamics of the optical signal is strongly reduced in graphene paper, where the out-of-plane bond is disrupted, while the short component of the dynamics is identical in both materials. These results show that in 2D-graphene, the carrier relaxation occurs in ≃200fs. [Copyright &y& Elsevier]

Strategies for changing the conductivity of Li 2 CO 3 is introduced into the fabrication of Li-CO 2 battery. Benefitting from the favorable hierarchical architecture constructed (CPM-MnO 2), facile charge transfer occurs between catalytic surface and Li 2 CO 3 by –OH⋯O hydrogen bonds improves the metallicity of Li 2 CO 3 , facilitating the formation/decomposition of Li 2 CO 3 and bestowing an ultra-long-term stability of 1087 cycles (4348 h). Taking into account its simplicity, scalable character and outstanding performance, this hierarchical composite electrode paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [Display omitted] • Excellent hierarchical structure of MXene and MnO 2 on carbon paper was fabricated. • Enriched charge transfer occurred on MXene and the MnO 2 by OH⋯O hydrogen bonding. • The prepared batteries showed an ultra-long cycle lifetime and low overpotential. • The optimized electronic structure can improve the metallicity of Li 2 CO 3. • The accelerated decomposition of discharge products promoted CRR and CER kinetics. Lithium-CO 2 batteries are recognized as an essential strategy for efficient carbon sequestration and energy storage to achieve carbon neutrality. Their cycle-ability and polarization voltage, however, are hindered by high decomposition voltage (≈4.3–4.5 V) of insulating Li 2 CO 3. Herein, we report a significant advance toward the rational design of self-supporting and ultra-long cycle lifetime cathode for Li-CO 2 batteries, dependence on a favorable hierarchical architecture and rich charge transfer constructed by homogeneously distributed MnO 2 nanoplates rooted in the MXene surface supported by carbon paper. Detailedly, it exhibits impressive ultra-long-term stability of 1087 cycles (4348 h) with a low polarization gap (≈ 0.47 V) at a high current of 200 μA cm−2, which is outperformed by all the liquid electrolyte-based Li-CO2 batteries reported previously. Electronic structure analysis reveals that facile charge transfer occurs between catalytic surface and Li 2 CO 3 , springing from the –OH functional group (in MXene) to MnO 2 by –OH⋯O hydrogen bonds, which acts as charge transfer channels, improving the metallicity of Li 2 CO 3 and facilitating its decomposition and extending battery cyclability. This work paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [ABSTRACT FROM AUTHOR]

The as-prepared NCMOF/expanded graphite paper (NCMOF/EGP) exhibits high specific capacitance of 2.41 F cm−2 at 0.5 A cm−2, and still retain the specific capacitance of 1.75 F cm−2 even at 20 A cm−2, indicating the excellent rate capability. • NiCo-MOF/EGP composite has three-dimensional hierarchical structure. • NiCo-MOF/EGP electrodes have a high capacitance of 2.41 F cm−2 at 0.5 A cm−2. • The supercapacitor show high energy density of 0.11 mW h cm−2. • The capacitance retention of supercapacitor device is 71.2% after 10,000 cycles. Metal-organic frameworks (MOFs) are considered as a promising energy storage material owing to their inherent advantages of large surface area, regulatable pore size and functional groups. However, the relative poor electronic conductivity is an obstacle to their wide practical application. Herein, the partially-exfoliated graphite paper (EGP) composed of graphene nanosheets is prepared by a controlled cathodic exfoliation. EGP exhibits 3D hierarchical porous structure and good electronic conductivity, which acts as an ideal substrate for growing accordion-like structure NiCo-based bimetal-organic framework (NCMOF). The as-synthesized NCMOF/EGP shows high areal specific capacitance of 2.41 F cm−2 at 0.5 mA cm−2, and good rate performance of 72.6% at the current densities from 0.5 to 20 mA cm−2. Furthermore, the constructed NCMOF/EGP//active carbon delivers an energy density of 0.11 mW h cm−2 at a power density of 0.75 mW cm−2, and long cycle life. The outstanding electrochemical energy storage performance of NCMOF/EGP are assigned to 3D hierarchical porous structure and good electronic conductivity of EGP combined with layered structure of NCMOF. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we present electronic and optical properties of two important scintillating materials: the Bi4Ge3O12 (BGO) and the Bi4Si3O12 (BSO). These properties were calculated by first-principles, density-functional theory based full potential augmented plane wave method. We discuss the differences between the band structures and optical constants of the BGO and BSO, and analyze the process of absorption of the radiation energy in these materials. Our results indicate that the major part of this energy is absorbed by the O p-electrons and then transferred to the Bi p-electrons. [Copyright &y& Elsevier]

In this paper the electronic structure of the valence states in CuInSe 2 , CuGaSe 2 and CuIn 0.5 Ga 0.5 Se 2 is considered in details in a wide energy range up to 20 eV from the Fermi level. Examining the electronic structure within the LDA + U method we focus on the deep, occupied 4d indium and 3d gallium electronic states. The calculated electronic structure is compared with high-resolution experimental photoemission (PE) spectra measured for high structural quality single crystals of these compounds at a photon energy of 600 eV. The comparison helped us to understand the nature of the observed spectral features associated with electronic states near the Fermi level. The calculated energies of the Ga-3d and In-4d states exhibited a good agreement with the experimentally determined spectral positions of these states in the PE spectra. The significance of these states for the application in quantum optics is discussed. • The electronic structure of Cu(In,Ga)Se 2 is studied within LDA + U method. • The calculations are found to be in a good agreement with the photoemission spectra. • We explore the effect of spin-orbit coupling of the deep 4d In and 3d Ga states. • We discuss the influence of deep states on applications in quantum optics. [ABSTRACT FROM AUTHOR]

The synergistic effect between metals is of great significance for improving the performance of materials, but the mechanism of synergistic catalytic of bimetallic has rarely been reported in the hydrolysis of sodium borohydride (NaBH 4 , SB). In this paper, a flower shaped Co 2 FeO 4 catalyst with high catalytic performance was selected from a series of Co x M 3-x O 4 (M = Fe, Ni, Cu) catalysts by controlling the composition. Based on the results of XPS characterization and density functional theory (DFT) calculation, the influence of component control on catalytic performance was discussed and explained from the perspective of electronic structure, and the "valence band center" and "D-band center" descriptors were introduced into the SB hydrolysis reaction. The simulation analysis results showed that the synergistic effect between Co–Fe elements resulted in the smallest center shift of the D band, the smallest binding energy of the hydrolysis reaction, and the best promoting effect on the electronic structure, manifested as the best catalytic performance. The calculation results were consistent with the XPS characterization results and the experimental results of hydrolysis performance testing, revealing the principle of bimetallic synergistic effect on catalytic performance. The synergistic effect between metals is of great significance for improving the performance of materials, but the mechanism of synergistic catalytic of bimetallic has rarely been reported in the hydrolysis of sodium borohydride (NaBH 4 , SB). In this paper, a flower shaped Co 2 FeO 4 catalyst with high catalytic performance was selected from a series of Co x M 3-x O 4 (M = Fe, Ni, Cu) catalysts by controlling the composition. Based on the results of XPS characterization and density functional theory (DFT) calculation, the influence of component control on catalytic performance was discussed and explained from the perspective of electronic structure, and the "valence band center" and "D-band center" descriptors were introduced into the SB hydrolysis reaction. The simulation analysis results showed that the synergistic effect between Co–Fe elements resulted in the smallest center shift of the D band, the smallest binding energy of the hydrolysis reaction, and the best promoting effect on the electronic structure, manifested as the best catalytic performance. The calculation results were consistent with the XPS characterization results and the experimental results of hydrolysis performance testing, revealing the principle of bimetallic synergistic effect on catalytic performance. [Display omitted] • Flower-like Co 2 FeO 4 showed the best catalytic performance. • The "D-band center" and "valence -band center" of Co 2 MO 4 were studied. • Composition and electronic control improve the catalytic performance of Co 2 MO 4. • The adsorption configuration of H 2 O on the Co 2 MO 4 (311) surface was studied. [ABSTRACT FROM AUTHOR]

A new fluorogenic probe, COUBM (where, COUBM = 3-(1H-benzoimidazol-2-yl)-8-benzothiazol-2-yl-chromen-2-ylideneamine) is developed for selective and rapid detection of phosgene in solution and gas phase. In presence of phosgene, the probe COUBM exhibits a sharp increase in the fluorescence intensity at 449 nm in solution. Moreover, the probe is efficiently used to detect phosgene in vapor phase using the COUBM loaded filter paper kit. • The new fluorogenic sensor, COUBM is designed for selective and rapid detection of phosgene. • COUBM is efficiently utilized for dual mode detection of phosgene both in solution and vapor phase. • The enhancement of fluorescence intensity of COUBM in presence of phosgene is interpreted by inhibition of PET process. • COUBM loaded filter paper strip is successfully used for the detection of phosgene. A new fluorogenic probe, COUBM (where, COUBM = 3-(1H-benzoimidazol-2-yl)-8-benzothiazol-2-yl-chromen-2-ylideneamine) is designed and synthesized for selective and rapid detection of phosgene both in solution and gas phase. COUBM reacts with phosgene to form a cyclic carbamylated product (COUBM-PHOS) and consequently a sharp increase in fluorescence intensity is observed. The probe is efficiently used to detect phosgene in vapor phase using the COUBM loaded filter paper kit. Theoretical calculation by DFT/B3LYP/6−31+G(d) method is performed to interpret the electronic structure and the probable sensing mechanism of the probe for the detection of phosgene. [ABSTRACT FROM AUTHOR]

Using the WIEN2k code, first-principles simulations of ZrXH 3 (X = Zn, Cd) hydride perovskites are performed to determine their hydrogen storage properties. The purpose of this study is to investigate their structural, optoelectronic, hydrogen storage, mechanical and thermoelectric properties. The structural analysis demonstrates their stability through the heat of formation along with desorption temperature and shows that these compositions belong to the orthorhombic space group Cmcm (no.63). The band structure and density of states are estimated for electronic characteristics, indicating the metallic nature of both compositions. Analysis of elastic properties such as elastic constants, Pugh's ratio, bulk modulus, Poisson's ratio, and anisotropy factor are explored to determine the mechanical stability of these compositions and demonstrate their suitability as a transport medium in hydrogen storage systems even at higher pressure. To study the optical behavior of the perovskites under consideration for hydrogen storage applications, the dielectric parameters, dielectric constants, refractive index, optical conductivity, absorptivity, and energy loss function are studied. The present paper represents the initial theoretical effort toward future exploration of these materials for hydrogen storage applications. [Display omitted] Using the WIEN2k code, first-principles simulations of ZrXH 3 (X = Zn, Cd) hydride perovskites are performed to determine their hydrogen storage properties. The purpose of this study is to investigate their structural, optoelectronic, hydrogen storage, mechanical and thermoelectric properties. The structural analysis demonstrates their stability through the heat of formation along with desorption temperature and shows that these compositions belong to the orthorhombic space group Cmcm (no.63). The band structure and density of states are estimated for electronic characteristics, indicating the metallic nature of both compositions. Analysis of elastic properties such as elastic constants, Pugh's ratio, bulk modulus, Poisson's ratio, and anisotropy factor are explored to determine the mechanical stability of these compositions and demonstrate their suitability as a transport medium in hydrogen storage systems even at higher pressure. To study the optical behavior of the perovskites under consideration for hydrogen storage applications, the dielectric parameters, dielectric constants, refractive index, optical conductivity, absorptivity, and energy loss function are studied. The present paper represents the initial theoretical effort toward future exploration of these materials for hydrogen storage applications. • Stability of ZrXH 3 (X = Zn, Cd) hydride perovskites is confirmed by Enthalpy of formation. • ZrXH 3 (X = Zn, Cd) hydride perovskites have high value of decomposition temperature. • The gravimetric hydrogen storage capacities comes out to be 1.89 % and 1.46 % respectively. • Metallic behavior is reveled by electronic structure of these hydrides. [ABSTRACT FROM AUTHOR]

In this paper, detailed models of GaTe/XSe heterojunctions are constructed and geometrically optimised. The GaTe/InSe(X = Zn, In) heterojunction is calculated to be a Type-II direct bandgap semiconductor with a forbidden bandwidth of 1.26 eV based on the DFT study, while the GaTe/ZnSe heterojunction behaves as a Type-II indirect bandgap semiconductor with a forbidden bandwidth of 0.899 eV. The forbidden bandwidth reaches its maximum value at 2% of tensile strain. When the compressive strain reaches −8%, the forbidden bandwidth is 0 and the heterojunction is converted from a semiconductor to a conductor. The analysis of the absorption spectra of GaTe/InSe and GaTe/ZnSe heterojunctions shows that both heterojunctions increase the absorption in the visible region as well as broaden the absorption range of the spectrum. Therefore, GaTe/InSe heterojunctions are useful in the field of optoelectronic devices. • The band gap width of the GaTe/InSe heterojunction is calculated to be 1.254 eV, and this heterojunction is a direct band gap semiconductor. The band gap width of the GaTe/ZnSe heterojunction is 0.899 eV, and this material is an indirect band gap semiconductor. • GaTe/ZnSe and GaTe/InSe heterojunctions have good optoelectronic properties with smaller bandgap widths and a wider range of light absorption. [ABSTRACT FROM AUTHOR]

The developing of electrocatalytic energy conversion technology to replace traditional energy sources is an important way of addressing the exhaustion of fossil fuels as well as related issues of the environment. The exploitation of the electro-catalysts having favorable electro-catalytic activity and stability is the key to realize these technologies. Single atomic catalysts (SACs) with the greatest atom availability and distinctive electronic structures and coordination environments are prospective candidate catalysts for application in electrocatalytic CO 2 reduction and water splitting. The intrinsic structures of the central sites of the SACs also vary with species or coordination environments, which provides a new way to engineer SACs for electrocatalytic CO 2 reduction and water splitting electrocatalysis. This paper reviews the recent advances of SACs in electro-catalytic CO 2 reduction and water splitting in recent years. In addition, combining experiments and theories, this article also presents an outlining of the strategies of ligand junction environment modulation to improve the electrocatalytic performance. Finally, the main challenges facing current SACs are pointed out, and some possible development directions are suggested. • The advantages of atomic metal catalysts for electrocatalytic reactions are summarized. • Many advanced characterization techniques for SACs are presented. • Some methods for tuning the coordination environment of metal atoms are also demonstrated. • The perspective insights into the challenges and future directions are also provided. [ABSTRACT FROM AUTHOR]

In this paper, the structure and electronic properties of InP/PtS 2 heterojunction as well as the photocatalytic and solar hydrogen production efficiency are studied by first principles. Studies have shown that InP/PtS 2 heterojunction is type II band alignment, typical Z heterostructure, has strong light absorption coefficient in the absorption spectrumand, InP/PtS 2 heterojunction with an indirect bandgap of 1.97 eV，the band edge positions that meet the energy band prerequisites for water splitting across different pH levels，The band edge positions and light absorption capabilities have been modified through biaxial strain, with tensile strain enhancing the absorption capacity within the visible light spectrum ranging from 450 to 800 nm(nm). The InP/PtS 2 heterojunction achieves a solar-to-hydrogen conversion efficiency (ηSTH) of 32.5%, which is higher than that of most heterojunctions. The InP/PtS 2 heterojunction is anticipated to emerge as a promising contender for the next generation of photocatalysts. InP/PtS 2 heterojunction is a typical direct Z-scheme heterojunction, which can change its electronic and optical properties under strain, and may contribute to the fields of water splitting. The solar-to-hydrogen efficiency of the InP/PtS2 heterostructure can reached 32.5%. The absorption coefficient in the visible range is enhanced by the application of strain. [Display omitted] • Compared with InP monolayer and PtS 2 monolayer, InP/PtS 2 heterojunctions have better visible light absorption efficiency. • The InP/PtS 2 heterojunction achieves a solar-to-hydrogen conversion efficiency (ηSTH) of 32.5%, which is higher than that of most heterojunctions. [ABSTRACT FROM AUTHOR]

Vacancy engineering has repeatedly proven to be a powerful strategy for manipulating material properties. The important influence of selenium vacancies (V Se) on the physicochemical properties of rhenium diselenide (ReSe 2), exciting applications can be opened in areas such as catalysis and photoelectric devices. However, the effects of V Se on electronic structure, carrier lifetime, and electrochemical activity of ReSe 2 have remained inadequately explored and poorly elucidated. Herein, hydrothermal controlled growth of ReSe 2 with vacancy (V Se -ReSe 2) is used by different synthesis strategies, revealing its growth mechanism. An ethanol-assisted hydrothermal method based on carbon paper was used to adjust the V Se concentration by changing the time parameters. Mediated excitonic effects in the transient absorption (TA) spectroscopy and photoluminescence response of ReSe 2 regulated by V Se were characterized. The defect level (DL) leads V Se -ReSe 2 to produce a unique defect emission peak, and the V Se -mediated exciton dynamics problem was discussed. Moreover, the TA result of V Se -ReSe 2 shows that high V Se concentration prolongs carrier lifetime and causes high carrier separation efficiency and electron utilization. The electrocatalytic hydrogen evolution reaction of ReSe 2 catalyst revealed the ability of V Se concentration to regulate the electrochemical activity, which provides ideas for vacancy management catalyst performance. The presence of DL and the reduction of band gap are indicated by density functional theory, which confirms the regulatory effect of V Se concentration on the electronic structure of ReSe 2. This work proffers an optimal solution strategy for hydrothermal preparation of ReSe 2 , which demonstrates the feasibility of regulating electrochemical activity by vacancy engineering, and the excellent performance of V Se -ReSe 2 makes it show great potential in many fields such as water cracking and physical devices. [Display omitted] • A regulation strategy for the successful construction of V Se rich ReSe 2 nanoflowers was developed. • DFT investigated the reduction of the band gap and orbital contribution of ReSe 2 regulated by V Se. • Mediated excitonic effects in the TA and PL response of ReSe 2 regulated by V Se were analyzed. • The effectively regulate the HER activity of V Se -ReSe 2 were analyzed. Vacancy engineering is powerful for manipulating material properties. Selenium vacancies (V Se) exert significantly impact on the physicochemical properties of rhenium diselenide (ReSe 2), triggering applications in catalysis and photoelectric devices. However, the effects on electronic structure, carrier lifetime, and electrochemical activity are inadequately explored and poorly elucidated. Herein, hydrothermal-controlled growth of ReSe 2 with V Se is synthesized by different strategies. The ethanol-assisted hydrothermal method can adjust V Se concentration of ReSe 2 on carbon paper by time parameters. Mediated excitonic effects were characterized in the transient absorption spectroscopy and photoluminescence of V Se -regulated ReSe 2. The defect level produces unique defect emission peak, and the V Se -mediated exciton dynamics problem was discussed. The transient absorption result shows that high V Se concentration can optimize carrier lifetime, carrier separation efficiency, and electron utilization. The electrocatalytic hydrogen evolution reaction of ReSe 2 catalyst revealed the electrochemical activity regulation by V Se concentration, which provides ideas for enhancing catalyst performance. Density functional theory result confirms the role of selenium vacancies in the regulation of the electronic structure of ReSe 2. This work proffers an optimal solution strategy for hydrothermal preparation of ReSe 2 , and demonstrates the feasibility of regulating electrochemical activity by vacancy engineering. The excellent performance is beneficial for water cracking and physical devices. [ABSTRACT FROM AUTHOR]

The introduction of the entropy effect has paved the way for a new realm of research in high entropy oxide ceramics (HEOCs). Through ongoing exploration, numerous HEOCs with exceptional properties have been discovered. This review provides a comprehensive summary of the research progress on the entropy effect in HEOCs, covering aspects such as structure, preparation methods, properties, and applications. [Display omitted] In 2004, Yeh and Cantor introduced high-entropy alloys (HEAs), which maximize configurational entropy by utilizing nearly equal elemental molar ratios. These HEAs are valuable for exploring the central regions of phase diagrams. Building on this concept, Rost et al. proposed entropy-stabilized oxides in 2015, revealing that high-entropy oxides (HEOs) exhibit structural stability driven by entropy. This article provides a comprehensive overview of HEOs, with a specific focus on high-entropy oxide ceramics (HEOCs). The paper explores the origins of the high-entropy concept and the fundamental effects of high-entropy materials. It examines entropy from its basic definition and investigates microscopic atomic distribution, crystal-level distortions, and electronic structures. Additionally, the article introduces theoretical prediction methods applied to high-entropy materials. Furthermore, this review systematically summarizes HEOCs, encompassing three key aspects: crystal structure, preparation methods, and performance applications. Finally, the review concludes by proposing future research directions based on the current progress in HEOCs. [ABSTRACT FROM AUTHOR]

Engineering-efficient, stable and low-cost electrocatalyst is facing with essential demand for overall water cracking to generate hydrogen and oxygen. Higher activation energy and sluggish kinetics are the main limiting factors for improved yield. In this paper, ZIF-67 was applied to prepare porous metal sulfide and foreign Fe atoms were introduced to substitute Co atoms in situ in CoS to modulate the electronic structure of the active centers. The as-constructed catalytic system reveals expected pH-universal HER performance and alkaline OER activity, and requires quite small over-potentials. Our theoretical prediction verifies the effective charge transfer between the doped Fe atom and its neighboring S atoms on the surface and the chemical environment variation in the doping sites. In addition, the improved conductivity and the decreased activation energy barriers are calculated in the FeCoS catalyst, further explaining its superiority in catalyzing OER and HER processes. This strategy is expected to be expandable to multiple energy transformation applications and provide a constructive strategy for fast charge transfer in water splitting. [Display omitted] • Non-precious bifunctional electrocatalyst were facile established. • FeCoS/NF-2 exhibited excellent performance for HER in the full pH range. • The chemical environment variation in the doping sites was explored. • DFT calculation explained the reasons for the excellent properties. [ABSTRACT FROM AUTHOR]

In the field of research on renewable energy conversion and storage methods, the development of catalysts with excellent properties and outstanding stability for oxygen evolution reaction (OER) acting at various pH values has become a much-anticipated research focus. RuO 2 as a benchmark OER catalyst, its wide application has always been limited by slow reaction kinetics and limited persistence. In this paper, Mn-doped RuO 2 material was developed and the optimum doping ratio was identified for using as an OER electrocatalyst under general purpose pH media. Mn 0.1 Ru 0.9 O 2 exhibited a lower overpotential value of 224 mV in acidic environment with a Tafel slope value of 51.62 mV dec−1. Moreover, in alkaline and neutral environments, overpotentials of 231 mV and 376 mV were required to obtain a current density of 10 mA cm−2, respectively. In addition, through continuous stability testing over 24 h in alkaline, acidic and neutral solutions, it has been further demonstrated that the Mn-doped RuO 2 material exhibits extremely high stability. The advancements in this research offer crucial insight into the rational development of efficient and durable RuO 2 -based catalysts. [Display omitted] • Mn 0.1 Ru 0.9 O 2 is successfully synthesized by a facile sol-gel method. • Mn doping modulates the electronic structure of RuO 2. • The catalyst exhibits enhanced OER activity and stability in pH-Universal media. [ABSTRACT FROM AUTHOR]

Introducing the second metal is an effective strategy to ameliorate oxygen reduction reaction (ORR) performance of cobalt and nitrogen doped carbon materials (Co-NC). In this study, Sn modulated Co-NC catalysts with enriched active sites (CoSn-NC) were synthesized by using formamide as ligand. Co and Sn bimetals coexist on nitrogen-doped carbon carriers and coordinated with nitrogen to form M − N active centers. Compared with Co-NC, CoSn -NC exhibited outstanding catalytic activity in terms of early initial potential of 1.04 V and positive half-wave potential of 0.89 V. Electrochemical testing and XPS characterization proved that the addition of Sn enriched the active site of Co-NC. More importantly, the electronic structure of Co–N is adjusted to perfect adsorption energy of the intermediate. The study puts forward a new idea and direction for optimizing single metal Co-NC catalyst. Synopsis: This paper is committed to developing Cobalt-based bimetallic materials with enrich active sites to replace scarce Pt/C for ORR. [Display omitted] • Co and Sn bimetals coexist on nitrogen-doped carbon carriers. • Sn Modulated Co-NC catalysts with enriched active sites. • The M − N structure is the main catalytic site by SCN− toxicity experiments. • CoSn-NC shows enhanced ORR catalytic activity, stability and methanol resistance. [ABSTRACT FROM AUTHOR]

Recently, transition metal dichalcogenide photocatalysts have been substantially explored as efficient catalysts for water splitting. This paper systematically investigates the electronic structure and related properties of four, hitherto uninvestigated, Janus MoSSe/Ga 2 SSe vdW heterostructures using first-principles calculations. The results indicate that two out of the four heterostructures exhibit a type-II energy band arrangement, which facilitates the effective separation of electron-hole pairs in space. Additionally, the electrostatic potential, charge density difference and Bader charges analyses indicate that charge transfer in the interfacial region creates a built-in electric field that effectively inhibits electron and hole complexation, and that one out of the four heterostructures corresponds to a direct Z-scheme heterojunction. The optical absorption coefficients show that the MoSSe/Ga 2 SSe vdW heterostructures have a broad absorption range from visible to ultraviolet. These findings suggest that the Janus SMoSe/SGa 2 Se and SMoSe/SeGa 2 S vdW heterostructures could be suitable for photocatalytic water decomposition. The SMoSe/SGa 2 Se and SMoSe/SeGa 2 S vdW heterostructures have high corrected solar-to-hydrogen (STH) efficiency of 11.84% and 10.13%, respectively. [Display omitted] • Two Janus MoSSe/Ga 2 SSe vdW heterostructures are found type-II heterojunctions. • One of the type-II heterojunctions is a candidate as direct Z-scheme photocatalyst. • The built-in electric field can promote the separation of charge carriers. • Heterostructures band positioning are suitable for water splitting. • The heterostructures exhibit a broad absorption range from visible to ultraviolet. [ABSTRACT FROM AUTHOR]

• Nanostructure of SnO 2 doped with Fe ions were synthesized through co-precipitation method. • XRD pattern infer the single phase nature of Fe doped SnO 2 nanoparticles. • Band gap engineering of Fe doped SnO 2 nanoparticles. • NEXAFS study infers that Fe in mixed valence state. This paper presents the electronic structure and optical behavior of Sn 1-x Fe x O 2 (0 % ≤ x ≤ 7 %) nanoparticles synthesized using co-precipitation assisted hydrothermal method. The structural properties of as-synthesized nanoparticles were examined using XRD and Raman spectroscopy. The XRD results demonstrated that all the samples are crystallized in tetragonal (rutile) crystal structure without any hint of impurity phase. The crystallite sizes measured using XRD spectra were found to vary from 7.0 to 10.0 nm. The effect of Fe doping and local defects were identified via surface-enhanced Raman spectroscopy (SERS). The local electronic structure was studied using NEXAFS at Fe L 3, 2 , O K edges which demonstrate that Fe ions are situated at the Sn sites with Fe3+ (pre-dominant) and Fe2+ (minor) mixed valance states. The octahedral (O h) ligand field split the Fe (3d) state into t 2g and e g states with ∼ 3 eV energy splitting. The optical properties were explored by using UV–vis spectra, which reveals transparent behavior in the visible light region and good absorption in the ultraviolet range. The asymmetrical change in the bandgap energy (3.6–3.1 eV) with the variation in Fe dopant level may be due to the casual distribution of Fe ions inside the host SnO 2 crystal texture. [ABSTRACT FROM AUTHOR]

To further enhance the long-term durability of the cost-effective Ir-based catalysts, some acid-stable oxides are used as supports for acidic OER catalysts. Herein, taking carbon paper (CP) as the substrate, we prepared a self-standing IrW/WO 3-x @NC/CP electrode via a layer-by-layer modified method. Among it, N-doped porous C framework not only provides a large specific surface for the attachment of WO 3-x , but also makes up for the lack of conductivity of WO 3-x and accelerates the electron transport process. The interaction between Ir and W sites in the form of IrW alloy which has generated during the high-temperature calcination and the dispersed Ir in WO 3-x matrix improve the intrinsic catalytic activity. And due to the Pt-like effect of W and the tuning role of the electronic structure by the IrW alloy, IrW/WO 3-x @NC/CP with an Ir content of only 19.1 µg cm−2 exhibits excellent bifunctional activity in acidic media. To obtain 10 mA cm−2, IrW/WO 3-x @NC/CP just needs overpotential of 22 mV (for HER) and 206 mV (for OER) respectively with a mass specific activity of 4.008 A mg Ir −1 at 1.55 V. For the whole water splitting, it only requires 1.52 V and 1.70 V to reach 10 mA cm−2 and 100 mA cm−2 respectively, and can operate continuously for over 40 h. [ABSTRACT FROM AUTHOR]

• N-doped CoSe 2 on carbon paper is prepared by hydrothermal and plasma nitridation. • N- possesses numerous active sites and beneficial electronic structures. • N- needs 106 mV and 237 mV to drive 10 mA cm−2 towards HER and OER. • Only 1.57 V is required to arrive at 10 mA cm−2 for overall water splitting. N-doped CoSe 2 porous nanomesh arrays grown on carbon paper (N-CoSe 2 @CP) have been prepared through hydrothermal method followed by a facile plasma nitridation strategy. The obtained N-CoSe 2 @CP electrodes combine advantages of abundant electrochemical active sites and beneficial electronic structures induced by porous structure and N doping, respectively, thus exhibiting low overpotentials towards HER and OER in alkaline medium. Moreover, it can also be employed as an excellent bifunctional electrocatalyst for overall water splitting. [Display omitted] CoSe 2 has been as one of promising electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) due to its earth-abundant resource, and tunable electronic structure. However, enhancing electrocatalytic activity of CoSe 2 to meet the large-scale practical applications is desirable. Herein, we report a facile plasma nitridation strategy to generate N-doped CoSe 2 nanomesh arrays on commercial carbon paper (N-CoSe 2 @CP). The obtained N-CoSe 2 @CP electrodes combined advantages of abundant electrochemical active sites and beneficial electronic structures, thus exhibiting a low overpotential of 106 mV and 237 mV to drive 10 mA cm−2 towards HER and OER in alkaline medium, respectively. Moreover, it can be employed as bifunctional electrocatalyst for overall water splitting, where a small potential of 1.57 V was required to reach 10 mA cm−2, and long-term stability was also realized. This work develops a promising strategy to explore highly-efficient nanocatalysts towards new energy conversion. [ABSTRACT FROM AUTHOR]

The first principle of calculation is a computational technique based on quantum mechanics that may precisely determine the ground-state electronic structure and associated mechanical and thermodynamic characteristics of solid materials. This study explains the history of first-principles development, calculation techniques, and the use of ultra-soft pseudopotential in hydrogen storage materials based on an inquiry and analysis of the findings of previous research. This paper primarily reviews the research progress of first principles in improving two-dimensional hydrogen storage materials, metal-organic framework materials, alkali metal-base composite hydrides, and metal-base hydrogen storage materials in order to speculate on the hydrogen storage mechanisms of materials. It is possible to estimate the location of hydrogen adsorption in a material by computing its electronic structure, band structure, electron density, and lattice vibration. This information is then used to compute the hypothetical new hydrogen storage material. Finally, the direction of first-principles computing in hydrogen storage materials is anticipated. • The research progress of DFT in predicting and simulating new hydrogen storage materials is introduced. • The merits and demerits of the application of DFT in solid hydrogen storage and its future development direction are pointed out. [ABSTRACT FROM AUTHOR]

Improving the catalytic activity and long-term stability of catalysts have always been the goal of its application. The structure stability and good electrical conductivity of catalysts are the key to OER performance, which have been challenge for application of catalysts. In the paper, we designed an in-situ growth of hierarchical core-shell structure CuMn 0.5 Co 2 O 4 @CC with superior conductivity directly as the catalytic electrode for improved OER performance. The well-standing CuMn 0.5 Co 2 O 4 nanoneedles with mesoporous structure entirely encapsulated on the carbon fibers, exposing a large special surface area and structural stability, while carbon fibers improved its electrical conductivity. Meanwhile, the richer oxygen vacancies and self-regulating electronic structure by the diversification of the metal oxidation state in the catalyst would promote the OER activity and stability. Benefitting from these merits, the requiring overpotential of CuMn 0.5 Co 2 O 4 @CC was 189 mV at the current density of 10 mA cm−2 and the Tafel slop value was 64.1 mV⋅dec−1, which was lower than that of CuMn 0.5 Co 2 O 4 //CC (η 10 = 337 mV and Tafel slop value of 113.9 mV⋅dec−1). In addition, the CuMn 0.5 Co 2 O 4 @CC had a competitive stability of with the current retention rate of 95.3 % after 1000 cycles. The present work provide a useful attempt to construct highly catalytic active and durably stable metal oxide composite catalysts. The synthesized CuMn 0.5 Co 2 O 4 @CC electrode exhibited the excellent OER activity (η 10 = 189 mV and Tafel slope of 64.1 mV⋅dec−1) and higher stability (the current retention rate of 95.3 % after 1000 cycles), which was attributed to the excellent conductivity of carbon fiber, the large surface area of active ingredients, and the regulated electronic structure with adjacent elements. [Display omitted] • The large special surface area and coupled with high structural stability for CuMn 0.5 Co 2 O 4 @CC catalyst. • The richer oxygen vacancies and self-regulating electronic structure promote the OER performance. • The improving OER activity and stability was attributed to the synergetic coupling effect between CC and CuMn 0.5 Co 2 O 4. • A lower overpotential of 189 mV, Tafel slop of 64.1 mV⋅dec−1, and the current density retention of 95.3 % were obtained. [ABSTRACT FROM AUTHOR]

The design of nanostructures and the adjustment of components are very important to improve the performance of hydrogen evolution electrocatalysts. In this paper, Ni, W and Mo trimetallic catalysts are studied from the aspects of morphology, structure and electronic transfer, and a better combination of hydrogen reaction efficiency is obtained. The W/Mo co-doped nickel sulfide electrocatalyst was synthesized on Ni foam by one-step hydrothermal method. As anticipated, the individual incorporation of either tungsten (W) or molybdenum (Mo) into the electrocatalyst did not yield satisfactory enhancements in hydrogen evolution reaction (HER) performance. However, when both W and Mo were co-doped onto the electrocatalyst, a significant improvement in catalyst material performance was observed. Hence, the coexistence of W and Mo is the key to improve HER electrocatalytic activity. In 1 M KOH solution, the W/Mo-Ni 3 S 2 /NF electrocatalyst exhibited exceptional HER activity with an overpotential of only 136 mV at a current density of 10 mA·cm−2 and demonstrated excellent cycle stability exceeding 20 hours. In this paper, the strategy of bimental co-doping composite is adopted to adjust the structure of nickel sulfide, which provides reference value for the design of reasonable and efficient HER electrocatalyst. • Due to the combined action of tungsten and molybdenum elements, the electrocatalyst forms a unique nanowire structure. • The combined action of bimetallic elements results in an electrode material with superhydrophilic and aerophobic properties. • The nanowire structure provides greater roughness to the surface of the electrode material, increasing the exposed active sites, thereby improving the overall performance of the electrocatalyst and maintaining better stability in long-term testing. [ABSTRACT FROM AUTHOR]

To explore novel high-performance nonlinear optical (NLO) materials, this paper focuses on studying and discussing the geometric, electrical, and NLO properties of superalkali-doped C 6 H 6 F 6. Geometrical and thermodynamic properties have been calculated by density-functional theory (DFT) calculations at the ωB97XD/6-31 + G (d,p) level of theory. Electronic properties related to charge transfer between the superalkali and C 6 H 6 F 6 were obtained through calculations such as NBO charge analysis and frontier molecular orbitals (FMO). The electronic properties are rationalized by the density of states analysis, and in this paper, using the two-energy level model to analyzed the factors that affect the first hyperpolarizability. The frequency-dependent hyperpolarisation coefficients are analyzed to understand the dynamic NLO response. To obtain the NLO response of these new complexes experimentally, the Hyper-Rayleigh scattering (β HRS) coefficients of the complexes were also investigated. The dynamic and static hyperpolarizability properties of these complexes show good NLO response. It is also hoped that this work may provide theoretical help for the future synthesis of new efficient NLO materials. [ABSTRACT FROM AUTHOR]

The previous paper has indicated that it is important to depress both direct recombination and reverse reaction between ionic relaxation products, i.e., latent image centers (Ag n) and Br 2 for dark matter (DM) detection by a super-fine-grained nuclear emulsion named NIT. This paper describes the results of the analyses on the reverse reaction in the NIT containing a typical halogen acceptor Na 2 SO 3 (SS), which is used to make the NIT sensitive. The electronic structure of the NIT layer containing SS as measured by means of photo-electron yield spectroscopy in air revealed that Ag(SO 3) 2 3− was formed in emulsions and could become to be Ag(SO 3) 2 2−by giving an electron to Br 2. Although SS could not stop the reverse reaction, SS made it so slow that SS could make the NIT with SS available for DM detection when the irradiated NIT layers were kept at low temperature (−20 °C to −50 °C) in order to bring about further slowdown of the reaction rate. It is thought that Ag(SO 3) 2 2− took a place of Br 2 for the reverse reaction and decreased its rate, since the diffusion of Ag(SO 3) 2 2−, which is electrically charged and large in size, is slower than that of Br 2 owing to attractive interaction between Ag(SO 3) 2 2− and many ionized substituents in gelatin. Discussions are made on ideas to depress further the reverse reaction. [ABSTRACT FROM AUTHOR]

In recent years, spinel ferrites with chemical formula MFe 2 O 4 , have attracted much attention due to their impressive photocatalytic and electrocatalytic performances, which are significantly influenced by their spinel structures. However, it is still a big challenge to distinguish or predict spinel structures for spinel ferrites. As an attempt to address this issue, this paper presents a first-principles study of the thermodynamics and electronic structures for six spinel ferrites with different spinel structures. The configurational free energy of these spinel ferrites at different inversion degrees is calculated to determine the equilibrium inversion degree for each spinel, which successfully predicts the spinel structure type of these spinel ferrites. The partial density of states is obtained for six spinel ferrites assuming they are normal or inverse spinels. The electronic states close to the Fermi energy of each spinel ferrite are carefully examined, showing that normal spinels have weak interactions between M and Fe states, while strong interactions exist in mixed or inverse spinels. Our results offer an insightful understanding of different spinel structures, and provide a reliable approach to determine the spinel structure of spinel ferrites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ppb-level, ratiometric detection of pyrophosphate: Signal amplification. • Pyrophosphate induced demetallation which led to disassembly of probe molecule. • Electronic influence of spacer unit: rigid vs flexible spacer. • Detection in diluted blood serum samples and inside living cells. • On-location rapid detection using low-cost, reusable paper strips. In the present work, we have designed and synthesized two dimeric fluorescein derivatives with flexible salen (1) or a rigid salophen (2) linker unit. The Fe(III) complexes of these compounds ([ 1.Fe]+ and [ 2.Fe]+) showed changes in solution color specifically upon addition of inorganic pyrophosphate (PPi) at pH 7.0 in PBS buffer. Along this, we also observe appearance of green fluorescence (turn-on) in the prescence of PPi. The mechanistic studies suggested PPi-induced demetallation process, which led to disassembly for molecular structure in the aqueous medium and release of highly fluorescent fluorescein aldehyde. The disassembly process was found to be dependent on electronic structure, rigidity of the linker unit, temperature, and local pH etc. The selectivity as well as sensitivity of [ 1.Fe]+ towards PPi was also found to be superior than that observed with [ 2.Fe]+. Since each disassembly process released two signalling unit (fluorescein), we could observe a huge increment in FL intensity even with small quantity of PPi (<10 µM). Finally, the sensory system was utilized for detection of PPi in diluted blood serum samples and inside living mammalian cells (HeLa, cervical cancer cells). Chemically-modified paper strips have been developed for the detection of PPi in water samples at outside laboratory conditions. [ABSTRACT FROM AUTHOR]

In this paper, the crystal structure and electronic structure of Ti 4 O 7 were calculated based on density functional theory, and Magnéli phase Ti 4 O 7 bulks were successfully prepared by spark plasma sintering (SPS). Results indicated that the contribution of Ti 3 d to Fermi level increased due to the lack of oxygen atom in lattice, and the energy band gap of Ti 4 O 7 was reduced compared with that of TiO 2. By calculating the relationship between the densification rate and effective stress in the process of SPS, it can be known that the densification mechanism of Ti 4 O 7 powders was controlled by diffusion. Based on this, under the conditions of sintering temperature of 1000 °C, holding time of 10 min and sintering pressure of 30 MPa, Ti 4 O 7 bulks with the optimal electrical conductivity (961.5 S cm−1) could be obtained, which was more than 30% higher than the graphite material reported in literature. The results reveals that Ti 4 O 7 will be one of the most promising electrode materials in the electrochemical field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Inducing lattice distortion in NiFe-LDH nanosheets by Ce-doping towards accelerating electrocatalytic oxygen evolution reaction. • The optimal NiFeCe-LDH@CP only requires 267 mV to deliver 100 mA cm−2, which is 41 mV lower than pure NiFe-LDH@CP. • NiFeCe-LDH@CP have retained their structural property after 70 h stability. • DFT calculations reveal that lattice distortion could optimize the electronic structure of the Ni element in active sites and lower the energy barrier, thus accelerating the OER. Nickel-iron layered double hydroxide (NiFe-LDH) is a promising active electrocatalyst for oxygen evolution reaction (OER). However, the development of NiFe-LDH is limited by poor electrical conductivity and inferior cycling stability. Herein, we present a structural perturbation and distinct distorted lattice strategy via Ce doping in NiFe-LDH on carbon paper (CP) (NiFeCe-LDH@CP) to boost its OER performance. Lattice distortion results in a large accessible surface area and induces more O vac , accelerating the OER by modifying the intrinsic electronic structure and optimizing the adsorption energy of intermediates. As a result, the optimized NiFeCe-LDH@CP possesses excellent stability over 70 h and can deliver the current density of 100 mA/cm2 with the overpotentials of only 267 mV, which is 41 mV lower than pure NiFe-LDH@CP. Theoretical calculations indicate that the introduction of lattice distortion into NiFe-LDH could optimize the electronic structure of the Ni element in active sites and lower the energy barrier, thus leading to a significant increase in OER activity. This work figures out the effect of lattice distortion strategy on the improvement of OER performance, which opens new perspectives on the development of defect-rich OER electrocatalysts. [ABSTRACT FROM AUTHOR]

Herein, using first-principles density functional theory (DFT) calculations, we have investigated the effects of Bi substitution on the structural, electronic, and magnetic properties of barium hexaferrite (BaFe 12-x Bi x O 19 , x = 0; 0.5; 1.5 and 2). As a result of the calculation, it was determined that the most stable structure exists if the spin of the Fe atom on the 2a, 2b, and 12k positions of the barium hexaferrite compound is taken in the upward direction. The calculated lattice constant c a = 3.9 and magnetic moment (4.24 μ B) of iron ions are in reasonable agreement with other experimental works. Moreover, the presence of bismuth reduces the electronic band gap. Energy gain and magnetic anisotropy energy calculations for FIM, FM, and NM states were performed for the most stable states. It has been established that the most stable structural state is characteristic of х = 0.5. It has been calculated that substitution by the large Bi3+ ion dramatically changed the electronic structure and sharply reduced the band gap. This paper is the first step towards establishing the nature of the distribution of ions in M-type hexaferrites under conditions of substitution by ions with a large ionic radius. [ABSTRACT FROM AUTHOR]

Millions of people in poor areas are still under the threat of fluoride contamination. How to effectively separate fluorine in water is an important step to reduce the ecological risk. In this paper, we performed a systematic DFT calculation focused on the defluorination behavior between the LiAl- and MgAl-LDHs. The results indicated that the LiAl-LDHs exhibited high chemical activity before the defluorination, because of the better electronic structure. After the defluorination, the LiAl-LDHs with adsorbed-F– were also more stable than the MgAl-LDHs. In addition, the existence of coordination covalent bond for the adsorbed-F– attached to the LiAl-LDHs was confirmed. This is an important reason for the high defluorination efficiency by the LiAl-LDHs. In addition, a series of weak interaction, including hydrogen bond and van der Waals interaction were also observed. Finally, a LiAl-LDHs with excellent fluoride removal properties were synthesized well by simple hydrothermal method. The results showed that our synthesized LiAl-LDHs with the capacity of 156.09 mg/g, could be effectively defluorinated in water. Notably, it surpasses most materials and has potential applications. [Display omitted] [ABSTRACT FROM AUTHOR]

With the development of industrialization, the use of mercury in industry has become more and more widespread, causing serious impacts on the environment. It is therefore urgent to find new effective ways to combat mercury pollution. In this paper, The effect of C, O, P, Ni and Au doping on the adsorption of Hg atoms by WS 2 has been investigated based on the first nature principle of density functional theory. The electronic structures and optical properties of the adsorbed systems were calculated after atomic doping. The results show that the absolute value of the adsorption energy of the intrinsic adsorption system is small and does not favour the adsorption of Hg on WS 2. However, after C, P, Ni and Au doping, the adsorption energy of the system is significantly increased and a strong charge transfer between WS 2 and Hg atoms occurs, as well as a significant change in the band gap of the structure. This suggests that atomic doping favors the adsorption of Hg by WS 2. The effect of O doping on the adsorption system is not significant. In addition, a study of the optical properties revealed that the static dielectric constants of the system appeared to increase to varying degrees after the doping of the atoms. The doping of P, Ni and Au atoms increases the light absorption coefficient and contributes to the photocatalytic efficiency of the structures. The doped atoms cause a red shift in the reflectivity peak of the adsorbed system. In summary, the doping of C, P, Ni and Au enhances the adsorption of Hg atoms on WS 2. O doping has less effect on the adsorption of Hg on WS 2. • In this paper, the effect of C, O, P, Ni and Au doping on the adsorption of Hg atoms by WS2 was investigated. • The results show that atomic doping favors the adsorption of Hg by WS2. • Atomic doping alters the electronic properties of the structure. • Atomic doping alters the optical properties of the structure. [ABSTRACT FROM AUTHOR]

The application of a potential model to the analysis of differences between the Auger parameters of InSb and the elemental materials yields a value 1.82 ± 0.07 Å for the core hole screening distance in InSb. It also yields a value of 0.22 ± 0.49 e for the charge transfer in InSb. Shifts in the Auger parameters of elements between their metallic states and in a compound semiconductor are interpreted using a novel method based on quantifying atomic core potential, as a quantum mechanical observable, in terms of its dependence on the valence charge and the number of atomic core holes. The core hole screening distance is ∼ 30 % larger than half the interatomic distance between the nearest neighbors and, by the equivalent cores model, is expected to be the screening radius of Sn and Te impurities in InSb. • The main achievement of this paper is to determine the core hole screening distance in InSb. • The paper shows this has a value of 1.82 ± 0.07 Å. • The paper also establishes a method of determining charge transfer in semiconductors though the accuracy of this determination is rather poor: 0.22 ± 0.49 e. [ABSTRACT FROM AUTHOR]

Various trace minimization principles have interplayed with numerical computations for the standard eigenvalue and generalized eigenvalue problems in general, as well as important applied eigenvalue problems including the linear response eigenvalue problem from electronic structure calculation and the symplectic eigenvalue problem of positive definite matrices that play important roles in classical Hamiltonian dynamics, quantum mechanics, and quantum information, among others. In this paper, Ky Fan's trace minimization principle is extended along the line of the Brockett cost function tr (D X H A X) in X on the Stiefel manifold, where D of an apt size is positive definite. Specifically, we investigate inf X ⁡ tr (D X H A X) subject to X H B X = I k (the k × k identity matrix) or X H B X = J k , where J k = diag (± 1). We establish conditions under which the infimum is finite and when it is finite, analytic solutions are obtained in terms of the eigenvalues and eigenvectors of the matrix pencil A − λ B , where B is possibly indefinite and possibly singular, and D is also possibly indefinite. [ABSTRACT FROM AUTHOR]

• Heterojunction models consisting of stacked semiconductor monolayer and half-metallic monolayers is designed. • The MoSi 2 N 4 /ScSi 2 N 4 heterojunction has robust half-metallic behavior and tensile anisotropy at equilibrium. • The physical properties of MoSi 2 N 4 /ScSi 2 N 4 heterojunction can be modulated. Heterojunctions formed by stacking different two-dimensional monolayer materials typically have tunable electronic properties, which will greatly broaden the application prospects of 2D materials in electron devices. In this paper, the structures, electron properties, and anisotropy of MoSi 2 N 4 /ScSi 2 N 4 heterojunctions formed by stacking MoSi 2 N 4 monolayer with semiconductor properties and ScSi 2 N 4 monolayer with half-metallic properties have been systematically studied. The results show that Type-Ⅰ configuration has the most stable structure in terms of total energy, binding energy, phonon spectrum and molecular dynamics among the three configurations formed by MoSi 2 N 4 /ScSi 2 N 4 heterojunctions. The MoSi 2 N 4 /ScSi 2 N 4 heterojunction has robust half-metallic behavior and tensile anisotropy at equilibrium. At the same time, MoSi 2 N 4 /ScSi 2 N 4 heterojunction can still maintain stable ferromagnetic and half-metallic properties under large interlayer distance changes. Studies of magnetic anisotropy show that the direction of hard axis for MoSi 2 N 4 /ScSi 2 N 4 heterojunction is perpendicular to the 2D layer plane. The tunable properties of MoSi 2 N 4 /ScSi 2 N 4 heterojunction provides promising exploration for novel 2D materials. [ABSTRACT FROM AUTHOR]

Liquid organic hydrogen storage is a promising way of storing hydrogen. The development of efficient and low-cost dehydrogenation catalysts is still required to advance the commercialization of N -ethylcarbazole/dodecahydro- N -ethylcarbazole (NEC/H12-NEC) hydrogen storage and transport system. In this paper, PdNi bimetallic catalyst (Pd 3 Ni 1 /LDHs) supported on MgAl hydrotalcite was prepared by NaBH 4 and ultrasound-assisted stepwise reduction. Ultrasonic cavitation could excite the hydroxyl hydrogen of hydrotalcite in the form of hydrogen radicals to reduce PdCl 4 2− to Pd nanoparticles (NPs), and also promoted the formation of PdNi alloys as well as the dispersion of NPs. In the Pd 3 Ni 1 /LDHs catalyst, the average particle size of NPs was 1.98 nm, suggesting an excellent dispersion of Pd, Ni, and PdNi NPs. The electronic effects of Ni and Pd significantly improved the catalytic efficiency of Pd 3 Ni 1 /LDHs in H12-NEC dehydrogenation, resulting in a hydrogen release rate of 98.4 % after 6 h at 180 °C, surpassing that of Pd/LDHs. It can be considered that the dehydrogenation performance of Pd 3 Ni 1 /LDHs for H12-NEC is related to the alloy phase, electronic structure and NPs size. [Display omitted] • Pd 3 Ni 1 /LDHs bimetallic catalyst for H12-NEC dehydrogenation was prepared by NaBH4 and ultrasound-assisted stepwise reduction. • Ultrafine PdNi NPs and the strong electronic effect of Ni and Pd effectively improved the catalytic performance. • Pd 3 Ni 1 /LDHs showed high stability and proficient reusability during 6 consecutive cycles. [ABSTRACT FROM AUTHOR]

In this paper, local oxygen plasma treatment of SiC carbon surface epitaxial graphene (EG/SiC-C) samples was carried out by using an oxygen plasma processor. Some vacancy defects were introduced into the graphene, and the electronic structure of the graphene was regulated. After oxygen plasma treatment, the work function of EG/SiC-C increased, and the doping type gradually changed to P-type. Finally, a self-powered epitaxial graphene (EG)/SiC heterojunction UV photodetector with spot position response characteristics was prepared by reasonable device structure design. [Display omitted] • The SiC carbon surface epitaxial graphene samples with different vacancy defect degree were obtained by oxygen plasma process. • The existence state of defects and the regulation rule of electronic structure in SiC carbon surface epitaxial graphene were studied. • The self- powered system of UV detector was constructed. • Due to the local photodoping effect caused by the excitation light, the detector has spot position response characteristics. [ABSTRACT FROM AUTHOR]

In this paper, the structural, mechanical, electronic, and thermodynamic properties of Ir 3 TM (TM = Sc, Ti, and V) intermetallic compounds in the cubic (L1 2) and hexagonal (D0 19 and D0 24) phases are presented. The outcomes of the simulation rely on density functional theory (DFT) within the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) based on the full-potential linearized augmented plane wave (FP-LAPW) approach. The existing study was performed on the L1 2 cubic phase. in addition to hexagonal D0 24 and D0 19 phases, which may be relative but differ in the way that the atomic layers are stacked. The calculated total, cohesive energy, and heat formation suggest that the Ir 3 Sc compound can be stable in the D0 24 phase because of an overlap between the L1 2 and D0 24 phases with a total energy difference of around 0.026 eV/atom. Ir 3 Ti and Ir 3 V are more stable in L1 2 and D0 19 , respectively. From elastic constants calculations, it reveals that the studied compounds are mechanically stable and harder in the cubic phase than hexagonal phase. However, Ir 3 Sc has the lowest hardness due to its relative ductility. Inversely, Ir 3 V has the maximum hardness with a lack of ductility. It was observed that these compounds have an elastic anisotropy based on the three-dimensional Young's modulus surface, and Ir 3 Sc has the strongest anisotropy, while Ir 3 V has the weakest in the L1 2 phase. The total density of state (TDOS) calculations shows that Ir 3 Ti and Ir 3 V are stable in the L1 2 and D0 19 phases, respectively, except for the Ir3Sc compound which might undergo a martensitic transition. Also, the pseudogap for Ir 3 V moves quite close to the Fermi level, indicating that the covalent bonding in this compound is sharper than the other compounds. Moreover, via the quasi-harmonic Debye model within the Gibbs computational code, thermodynamic properties are calculated and analyzed with temperature and pressure. [ABSTRACT FROM AUTHOR]

In the two papers, (i) Pontremoli C, Chinigò G et al. Photosensitizers for photodynamic therapy: structure-activity analysis of cyanine dyes through design of experiments. Dyes Pigments 2023; 210:111047 and (ii) Yoo N, Lim JY et al. A study on red cyanine dyes employing bis(fluorosulfonyl)imide anions for color filters of virtual and augmented reality displays. Dyes Pigments 2023; 220:111734, it was suggested that the short wavelength sub-band in the electronic absorption spectra of symmetrical cyanine dyes corresponds to the HOMO-LUMO+1 electronic transition. However, all experimental observations lead to the explanation that the fine structure in the spectra is a vibronic fine structure and a sub-band is a vibronic transition from v = 0 to v ', where v is the vibrational quantum number of the totally symmetric carbon-carbon valence vibration of the polymethine chain in the ground electronic state S 0 and v ' is that in the first excited electronic state S 1. The long wavelength sub-band corresponds to the vibronic 0–0 transition and the first short wavelength sub-band to the vibronic 0–1 transition. [ABSTRACT FROM AUTHOR]

[Display omitted] • The structure of paritaprevir in protic and aprotic solvents was investigated. • The weak noncovalent interactions within different conformations in liquid environments were analyzed. • The antitumor potential of paritaprevir was elucidated through molecular docking. Macrocyclic molecules have emerged as significant contenders in drug development and supramolecular chemistry. Paritaprevir is a 15-membered macrocycle approved for the treatment of chronic Hepatitis C virus infection. The structural flexibility inherent in paritaprevir enables the presentation of diverse conformational features in solutions, thereby influencing its binding pattern with proteins. In this paper, we investigated the structural characteristics of paritaprevir in protic solvents (methanol and trifluoroethanol) as well as an aprotic solvent (acetonitrile) by using experimental electronic circular dichroism spectra combined with density functional theory calculations. Our study reveals that paritaprevir can adopt different molecular conformations due to its flexible carbon chain and the solvent environment. Conformer B is particularly stable in polar solvents because of the planar hydrophobic interactions between the phenanthridine and methylpyrazine groups. Density functional theory calculations-assisted structural analyses further disclosed the weak noncovalent interactions within the stable conformations of paritaprevir. Molecular docking of paritaprevir on different cancer proteins showed that the macrocycle was highly selective against lymphoma, endometrial carcinoma, colorectal cancer, and breast cancer. This suggests that paritaprevir could potentially serve as a promising lead compound for drug design targeting these specific types of cancers. The comparison between the low energy conformation and pharmacophore conformation (docking conformation) indicates that conformer B is the primary pharmacophore conformation of paritaprevir, providing important macrocyclic structural characteristics for future macrocyclic drug development. [ABSTRACT FROM AUTHOR]

The unique electronic structure of layered black phosphorus (BP) makes it an ideal candidate material for electrocatalytic oxygen evolution reaction (OER). Charge doping effectively improves the environmental stability and catalytic activity of BP by providing electron transfer channels and reducing charge transfer barrier. Therefore, based on the first principles calculation, this paper theoretically discusses how the intrinsic charge doping without introducing impurities changes the electronic structure and improves the catalytic activity of BP. It is found that charge engineering can effectively regulate and change the electronic structure and work function by stimulating the hybridization between different P- p orbitals, while maintaining the direct bandgap semiconductor characteristics of monolayer BP system. More importantly, in the catalytic process of OER, electrons and hole doping as free charges provide different donor and acceptor energy levels for the system depending on the doping concentration, and affect the adsorption capacity of monolayer BP to different reaction intermediates. At a certain doping concentration, the carrier mobility increases significantly, and the optimal Gibbs free energy and overpotential can be achieved in monolayer BP. These results provide new opportunities and possibilities for designing charge-engineered BP catalysts with adjustable electronic structure and excellent OER activity. [ABSTRACT FROM AUTHOR]

Iron (Fe3+) is an essential trace element in biological organisms. Abnormal concentrations of Fe3+ in aquatic possess the potential to disrupt normal physiological and metabolic processes in living organisms. Consequently, the pursuit of developing fluorescent probes for detecting Fe3+ concentrations in water samples is highly significant. The lone electron pair on the nitrogen atom of quinoline demonstrates outstanding coordination capabilities, enabling the selective detection of metal ions through coordination. Nevertheless, the interaction between metal ions and quinoline-based fluorescent probes tends to lead to nanoparticle aggregation, causing aggregation-caused quenching (ACQ) phenomena. This severely restricts the practical application of these probes. To address this challenge, the study utilizes quinoline as the foundational framework and modulates the excited-state electronic structure of quinoline derivatives through substituent effects. This facilitates the transition from ACQ to aggregation-induced emission (AIE). By integrating theoretical calculations, the paper proposes a comprehensive strategy for designing AIE molecules based on quinoline. This contribution provides innovative perspectives on AIE molecule design. Ultimately, the AIE property of the 8-MQB molecule is harnessed to develop a fluorescent probe capable of detecting Fe3+ in water samples. The fluorescence intensity exhibits a robust linear correlation with Fe3+ concentrations within the range of 5.0 μM to 0.3 mM. Moreover, the probe demonstrates exceptional resistance to interference from other metal ions. In conclusion, this research presents a universal strategy for designing AIE molecules and introduces an AIE probe for the rapid detection of Fe3+ concentrations in water samples. [Display omitted] • The modulation of quinoline derivatives' excited-state electronic structure via substituent effects shifts them from ACQ to AIE, enabling a novel Fe3+ AIE fluorescent probe. [ABSTRACT FROM AUTHOR]

Theoretical studies on CdS/BiOI heterojunctions are lacking; therefore, this paper studies their electronic structure and optical properties through density functional theory calculations. First-principles calculations were made to investigate the effect of introducing oxygen vacancy defects on the photocatalytic efficiency of CdS/BiOI. The band gap of CdS/BiOI was effectively narrowed compared to that of its constituent materials, resulting in a redshift of the absorption edge. Based on the obtained work functions, the difference in Fermi energy levels caused a spontaneous flow of electrons, resulting in band bending and the establishment of a local electric field. The electric field promoted the separation of electron–hole pairs. At the same time, the addition of oxygen vacancies created impurity levels, allowing light absorption to extend to the infrared region, further promoting carrier separation. Our study reveals the origin of the enhanced efficiency of CdS/BiOI heterostructures and also predicts the photocatalytic activity of CdS/BiOI heterojunctions after introducing oxygen vacancies. These results may facilitate the design of such structures with enhanced photocatalytic properties. • The electronic structure and optical properties of CdS/BiOI heterojunction are studied by using density functional theory, and the effect of introducing oxygen vacancy defects into the structure is predicted theoretically. • According to the band structure, density of state, 3D/2D charge density difference and work function calculated by the first principle, the electron transfer from BiOI to CdS can be analyzed, and the trend is enhanced after the introduction of oxygen vacancy defect. • The calculation of optical properties shows that the formation of heterojunction and the introduction of oxygen vacancy defects promote the enhancement of optical absorption intensity. • This paper supplements the theoretical calculation of vacancy in CdS/BiOI heterojunction. And defects are introduced into the heterostructure to enhance the catalytic performance of such materials. [ABSTRACT FROM AUTHOR]

When preparing SiC/Mg composites, alloy elements play key roles in the nucleation and interfacial wetting. In this paper, effects of Al, Zn and Zr additions on the Mg/SiC interfacial bonding properties were investigated comprehensively via method of first-principle calculations. Mg(0001)/SiC(0001) interfaces with different terminations and stacking sequences were built and C Ⅱ-T C Ⅱ top interface has the largest work of adhesion (W ad). Zn dopants can not improve the W ad for both C-T and Si-T interfaces. Al atom can only strengthen the C-T interface. Zr addition can greatly improve the W ad for both C-T and Si-T interfaces. W ad of C-T interfaces can reach up to 11.55 J/m2 and 12.55 J/m2 after doping 1 monolayer (ML) of Al and Zr atoms. Larger W ad can lead to lower contact angles of Mg on SiC surfaces, which can improve wetting and nucleation in SiC/Mg composites. Analysis of electronic structure shows that Al-C and Zr-C bonds have more covalent composition than the Mg-C bond, which is responsible for the improvement of interfacial bonding strength. Experimental results in references were also analyzed, which are in well agreement with our calculation results. [ABSTRACT FROM AUTHOR]

This paper studies the structural, mechanical, optical, and electronic characteristics of monolayer and bilayer ABC 3 (A Ga, In; B Si, Ge; C S, Se, Te). Their characteristics are obtained using the density functional theory with van der Waals (vdW) correction. The stability is confirmed by examining Born's criterion, cohesive energy, phonon dispersions, and COHP analysis. In addition, the stability of these monolayers against tensile strain is explored. The electronic properties are extensively studied through band structure, PDOS, and effective masses. The optical properties are investigated for possible applications in optoelectronic devices. In the following, bilayer ABC 3 with three different stacking orders is investigated. Most of the monolayers and bilayers ABC 3 show an indirect bandgap. The contributions of each element at the valence and conduction bands are explored through the projected density of the state. The effective mass is derived for the valence and conduction band valleys, whereas the Γ -valley shows the lowest effective mass. Additionally, both real and imaginary parts of the dielectric constant, electron energy loss spectra, and optical absorption are studied, which might lead to intriguing usages in photovoltaic and electroluminescent systems. The analysis of the optical properties reveals that the studied monolayers and bilayers have acceptable visible-range absorption characteristics. Furthermore, the monolayer and bilayer ABC 3 dielectric function and absorption coefficient spectra display prominent optical peaks in the UV light range. Due to their distinct band gaps and optical characteristics, monolayer and bilayer ABC 3 materials are good prospects for upcoming electrical and optoelectronic applications. [ABSTRACT FROM AUTHOR]

Regulating the dual active sites is crucial for enhancing the carrier-directed migration efficiency and shortening mass transfer distance of intermediates, particularly in photocatalytic overall water splitting. In this paper, we adopt in situ hydrothermal coupled gas phase chemical reduction methods to synthesize janus cobalt cocatalysts on g-C 3 N 4. Experimental measurement and density functional theory calculations show that the janus cobalt cocatalysts fine-tunes the local electronic structure of g-C 3 N 4 , which can greatly reduce energy barriers and shorten mass transfer distance of intermediates for reactions. And while the built-in electric field of CoP and CoO also further efficiently facilitates rapid directional separation of interface carriers of the cocatalysts. This study elucidates atom-level mechanisms underlying overall water splitting and offers valuable insights for rational design of high-performance catalysts for overall water splitting. As a result, the CoP/CoO@g-C 3 N 4 samples exhibit a remarkable enhancement in overall water splitting activity (133.2 μmol g−1 h−1 H 2 and 67.2 μmol g−1 h−1 O 2), surpassing that of the CoP@g-C 3 N 4 and CoO@g-C 3 N 4 samples by 1.4 and 3.8 times, respectively. [Display omitted] • The Janus cobalt structure vastly shorten mass transfer distance of intermediates. • The inherent electric field to further enhance the carriers directional separation. • Theoretical calculations demonstrated the reaction path of overall water splitting process. • CoP/CoO@g-C 3 N 4 photocatalysts exhibit remarkable performance in the overall water splitting process. [ABSTRACT FROM AUTHOR]

This paper reveals the mechanism of Hf and Ti doping promoting hydrogen release in ZrCoH 3. Different from previous experimental methods, this study employs the plane wave pseudopotential method and density functional theory to predict the relationship between the formation energy and electronic structure of the ZrCoH 3 -Hf/Ti system, and uses theoretical calculations to guide the modification design of ZrCoH 3. Firstly, by calculating the thermodynamic properties of the ZrCoH 3 -Hf/Ti system and combining the density of states theory, the bonding characteristics and dehydrogenation preference between H atoms and neighboring metal atoms in the ZrCoH 3 -Hf/Ti system are determined. Additionally, the electronic structure of the ZrCoH 3 -Hf/Ti system is calculated to elucidate the hybridization of bonding and antibonding orbitals between atoms in the ZrCoH 3 -Hf/Ti system. Moreover, D Co-d is utilized to measure the strength of antibonding interactions in the ZrCoH 3 -Hf/Ti system. The main cause of antibonding interactions in the ZrCoH 3 -Hf/Ti system is attributed to the variation in formation energy, and the change in antibonding interactions is sensitive to the variation in formation energy. Finally, a feasible method to improve the properties of ZrCoH 3 is proposed, which involves modifying the electronic structure to increase the partial density of states at the Fermi energy level, making the formation energy of hydrides less negative and forcing the structure to be more unstable. This method has potential application value in the modification of ZrCoH 3. [ABSTRACT FROM AUTHOR]

• CoPc/ g -C 3 N 4 composites were successfully synthesized for PMS activation. • CoPc/ g -C 3 N 4 composites exhibited enhanced dispersibility and hydrophilicity. • The electron redistribution resulted in electron-rich Co active centers. • CoPc/ g -C 3 N 4 composites exhibited significantly enhanced PMS activation capability. The catalytic performance of cobalt-based catalysts in Fenton-like reactions is significantly influenced by the electron density of Co centers. However, precise control of the electronic structure to enhance the degradation activity remains a challenge. This paper demonstrates a method to enhance the catalytic activity of cobalt phthalocyanine (CoPc) by modulating its electronic structure via integrating with graphitic carbon nitride (g -C 3 N 4). The electron redistribution between g -C 3 N 4 and CoPc was observed, resulting in electron-rich Co centers. Consequently, the CoPc/ g -C 3 N 4 composites exhibit significantly enhanced peroxymonosulfate (PMS) activation capability compared to CoPc and their physical mixtures. The improved catalytic performance is due to the electron-rich Co centers, better dispersion of CoPc, and enhanced hydrophilicity. This study proposes a novel strategy for the design of efficient PMS activation catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spinel Co 3 O 4 with cationic vacancy at tetrahedral or octahedral site are prepared. • Tetrahedral Co vacancy greatly enhances the OER activity of neighbour Co2+ site. • d-Zn 0.3 -Co 3 O 4 displays excellent OER performance in both alkaline and neutral media. • Vacancy structure is still preserved after 100 h stability test. Spinel Co 3 O 4 which possesses two types of Co sites such as Co2+ at tetrahedral site and Co3+ at octahedral site, has been regarded as a promising non-noble metal oxygen evolution reaction (OER) catalyst to replace the state-of-the-art IrO 2 catalyst. Constructing cationic vacancy is an effective method to regulate the electronic structure and optimize the catalytic performance of the active site. Therefore, the spinel Co 3 O 4 with Co vacancy at tetrahedral site (d-Zn 0.3 -Co 3 O 4) or at octahedral site (d-Al 0.3 -Co 3 O 4) were fabricated in this paper by alkali etching the corresponding Zn doped Co 3 O 4 or Al doped Co 3 O 4. Density of state (DFT) calculations show that the Co vacancy can enhance the d band center close to Fermi level. While Co vacancy at tetrahedral site can greatly enhance the catalytic activity of neighbour Co2+ site, which is even better than the traditional octahedral Co3+ site. Therefore, d-Zn 0.3 -Co 3 O 4 shows the superior OER activity gives a small 293 mV (1 M KOH) and 364 mV (1 M PBS) overpotential at 10 mA cm−2 and admirable long-term stability. [ABSTRACT FROM AUTHOR]