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1,4-Dimethylphenazine endoperoxide releases singlet oxygen with a half-life of 89 hours at 37 °C. The thermal cycloreversion reaction is accompanied by a strong increase in the emission intensity with a peak at 490 nm, due to the formation of the phenazine core. The endoperoxide is effective against cancer cells in culture medium and tumor spheroids, with singlet oxygen-mediated cytotoxicity. [ABSTRACT FROM AUTHOR]

Binary CN compounds received considerable interest in green energy and sustainable materials. However, the energy density and structural stability at the ambient conditions are usually mutually exclusive in high-nitrogen CN materials. In this work, CN20 is identified via ab initio evolutionary searches at 35 GPa, termed as P4¯21c-C(N5)4, in which carbon is only 4.11% in mass fraction but can provide enough electrons to stabilize the aromatic cycle-N5− anions. The results show that P4¯21c-C(N5)4 exhibits excellent thermodynamic and dynamic stability under the synthesis pressure, and the robust covalent structure of P4¯21c-C(N5)4 can be maintained under ambient conditions while releasing the pressure. The electronic structures indicate that P4¯21c-C(N5)4 possesses high chemical inertness because of its non-absorption of visible light with a well-proportioned charge distribution. In addition, the decomposition of P4¯21c-C(N5)4 can release an energy of 6.53 kJ g−1, which, to our knowledge, is the highest recorded among room-temperature stable binary nitrogen-rich compounds. The energy released can be further improved to 11.13 kJ g−1 under an oxygen-rich environment. Moreover, the detonation pressure of P4¯21c-C(N5)4 is up to 44.76 GPa, which is similar to that of a potential rocket propellant. In light of these hallmarks, P4¯21c-C(N5)4 is a promising low cost and environmentally friendly high energy density material. [ABSTRACT FROM AUTHOR]

Two-dimensional carbon nitrides (CxNy) have gained significant attention in various fields including hydrogen energy development, environmental remediation, optoelectronic devices, and energy storage owing to their extensive surface area, abundant raw materials, high chemical stability, and distinctive physical and chemical characteristics. One effective approach to address the challenges of limited visible light utilization and elevated carrier recombination rates is to establish heterojunctions for CxNy-based single materials (e.g. C2N3, g-C3N4, C3N4, C4N3, C2N, and C3N). The carrier generation, migration, and recombination of heterojunctions with different band alignments have been analyzed starting from the application of CxNy with metal oxides, transition metal sulfides (selenides), conductive carbon, and Cx′Ny′ heterojunctions. Additionally, we have explored diverse strategies to enhance heterojunction performance from the perspective of carrier dynamics. In conclusion, we present some overarching observations and insights into the challenges and opportunities associated with the development of advanced CxNy-based heterojunctions. [ABSTRACT FROM AUTHOR]

Layered double hydroxide (LDH) is frequently used for phosphate removal in water, while a desirable LDH adsorbent should have sufficiently high adsorption capacity and selectivity. To enhance the removal performance and selectivity of phosphate by LDH, La-doped layered double hydroxide/biochar (La–MgAl–LDH/BC) was synthesized by using a co-precipitation method. Investigation results showed that lanthanum (La) metal loading can significantly enhance the phosphate adsorption performance of La–MgAl–LDH. Then, the introduction of La–MgAl–LDH into BC improved the adsorption capacity of phosphate by the adsorbent, which is 1.8 times that of pure La–MgAl–LDH. The optimum La to Al molar ratio was 0.2 : 0.8 in La–MgAl–LDH materials, and the La–MgAl–LDH to BC mass ratio was 9.3 : 10. Furthermore, both La–MgAl–LDH and La–MgAl–LDH/BC exhibited an enhanced ability to resist interference from co-existing anions (Cl−, SO42−, NO3− and CO32−) compared to LDH. For batch experiments, the kinetic results indicated that the adsorption process of phosphate by La–MgAl–LDH/BC follows a pseudo-second-order kinetics model, reaching equilibrium quickly within 1 h. Furthermore, film diffusion and intra-particle diffusion simultaneously took place. The maximum monolayer phosphate adsorption capacity of La–MgAl–LDH/BC could reach 249.3 mg PO43− g−1 (513.6 mg PO43− g−1, converting to an equivalent La–MgAl–LDH). After four cycles, La–MgAl–LDH/BC showed good reusability, and over 63.5% of phosphate uptake was retained with minimal metal leaching. Additionally, phosphate could be rapidly removed from actual water and simulated water at low concentrations. The electrostatic attraction, ligand exchange, ion exchange and Lewis acid action jointly facilitate the adsorption of phosphate. [ABSTRACT FROM AUTHOR]

We conducted high-throughput calculations on the structure library of two-dimensional covalent organic frameworks (2D COFs), with the aim of finding new candidate materials as electron transport layers (ETLs) for the high-performance perovskite light-emitting diodes (PeLEDs). Starting with nearly 400 unique 2D COFs with hexagonal (hcb) topology, 23 candidates for β-ketoenamine linked 2D COFs composed of 1,3,5-triformylphloroglucinol (Tp) and linear diamines are identified by band structures. Interestingly, 2 β-ketoenamine linked 2D Tp-DAAQ and 2D Tp-DABDA with electron-accepting substituents, are the most promising candidates due to the optimal band edge and effective mass. Further, the nonpolarity of the Tp-DAAQ molecule makes it a more favorable choice for the ETL, as confirmed by nonadiabatic molecular dynamics that 2D Tp-DAAQ with anthraquinone diamine linker has a longer e–h nonradiative recombination time. This work provides a paradigm for the design of high-performance ETLs. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) β-TeO2 is a novel semiconductor with potential applications in electronic circuits due to its air-stability and ultra-high carrier mobility. In this study, we explore the possibility of using a 2D β-TeO2 monolayer for the detection of gaseous pollutants including SO2, NO2, H2S, CO2, CO, and NH3 gas molecules based on first-principles calculations. The adsorption properties including the adsorption energy, adsorption distance and charge transfer indicate that the interaction between 2D β-TeO2 and the six gases is via a physisorption mechanism. Among the six gas adsorption systems, the SO2 adsorption system has the most negative adsorption energy and the largest charge transfer. In addition, the adsorption of SO2 obviously changes the electrical conductivity of the β-TeO2 monolayer because the band gap decreases from 2.727 eV to 1.897 eV after adsorbing SO2. Our results suggest that the 2D β-TeO2 should be an eminently promising SO2 sensing material. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) heterostructures have been proposed as potential anode materials for lithium-ion batteries due to their large surface areas and excellent electronic properties. In this study, we employ first-principles calculations to investigate the structural stability, electronic properties, and ion diffusion behaviors of 2D graphene/C2N lateral heterostructures. Three species of (5, 26), (11, 26), and (17, 26) heterostructures are chosen to explore the effects of graphene components on electronic properties. The results show that graphene/C2N lateral heterostructures exhibit good dynamic stability due to a small lattice mismatch and strong chemical interaction at the heterojunction interface. By introducing zero-gap graphene, these heterostructures acquire good electronic conductivity with small direct band gaps. The component ratio of graphene can significantly tune the band gap, showing a monotonic decrease as the ratio increases. Moreover, the introduction of C2N components can greatly improve the lithium capacities of heterostructures. Small diffusion energy barriers (0.257–0.273 eV) and a low average operating voltage of 0.758 V are observed in graphene/C2N heterostructures. The effects of graphene components and valence states on Li migration are discussed. Our results demonstrate that the graphene/C2N lateral heterostructure can effectively combine the advantages of graphene and the C2N monolayer, showing great promise as an anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The utilization of conventional metal contacts has restricted the industrial implementation of two-dimensional channel materials. To address this issue, we conducted first-principles calculations to investigate the interface properties of C31 and MoS2 contacts. An ohmic contact and a low van der Waals barrier were found in the C31/MoS2 heterostructure. Our findings provide a promising new contact metal material for two-dimensional nanodevices based on MoS2. [ABSTRACT FROM AUTHOR]

In order to accelerate the application of quaternary optoelectronic materials in the field of luminescence, it is crucial to develop new quaternary semiconductor materials with excellent properties. However, faced with vast alternative quaternary semiconductors, traditional trial-and-error methods tend to be laborious and inefficient. Here, we combined machine learning (ML) with density functional theory (DFT) calculation to predict the bandgaps of 2180 quaternary semiconductors, most of which were undeveloped but environmentally friendly. The evaluation coefficient (R2) of the model using a random forest algorithm was up to 0.93 in ML. Four novel quaternary semiconductors with direct bandgaps: Ag2InGaS4, AgZn2InS4, Ag2ZnSnS4, and AgZn2GaS4, were selected from the ML model. Then their electronic structures and optical properties were further verified and studied by DFT calculations, which demonstrated that the four quaternary semiconductors had direct bandgaps, a small effective mass, and a large exciton binding energy and Stokes shift. Our calculation could significantly speed up the discovery of novel optoelectronic semiconductors and has a certain reference value for the study of luminescent materials and devices. [ABSTRACT FROM AUTHOR]

Exhaustive research of phase engineering of two-dimensional molybdenum disulfide (2D-MoS2) is currently ongoing to develop numerous applications, including optoelectronic devices, spintronics, and new platforms for the study of unconventional quantum phenomena. Therefore, it is urgently needed to achieve phase-controlled synthesis of MoS2 with a high quality and large area. However, the metallic phase MoS2 (1T-MoS2) synthesized by conventional chemical vapor deposition (CVD) is randomly distributed in the semiconductor phase (2H-MoS2) domain, and the position-controlled synthesis of the phase is not achieved. In this study, we achieved the controlled synthesis of the 1T-MoS2 domain in the 2H main phase. Salt-assisted CVD was used to induce V-atom doping at the right time by controlling the concentration of vanadium ions. The synthesis benefitted from 1D vapor–liquid–solid (VLS) growth and 2D vapor–solid (VS) edge expansion. The results of the growth controlled by regulating the NaCl concentration showed that the 1T phase was located at the three vertex domains of the MoS2 triangle. The distribution domains of 1T phase MoS2 can be confirmed by Raman mapping, X-ray photoelectron spectroscopy, and transmission electron microscopy. Furthermore, we calculated the doping rate of V atoms in VLS and VS modes based on the two-dimensional diffusion model and observed that the doping rate of V atoms in the VLS mode was approximately three times higher than that in the VS mode, which was consistent with the experimental results. The controllable phase-domain synthesis of 2D-MoS2 is beneficial to the preparation of nano-electronic devices and provides a platform for the study of physicochemical properties. [ABSTRACT FROM AUTHOR]

CD147 functions as the receptor of extracellular cyclophilin A (CypA) in various diseases, and CD147–CypA binding ulteriorly underlies the pathological process of various viral infections including HIV-1, SARS, and SARS-CoV-2. Although CyPA has been identified as a key intermediate pro-inflammatory factor, the mechanism by which CD147 cooperates with CypA in the development of the cytokine storm remains largely unknown, and the binding profile of CD147 with CypA remains to be elucidated as well. Here, we prepared three binding models of the CD147–CypA complex, including the active site of CypA severally binding to the groove bound by the Ig1 and Ig2 domains (model-0), P180-G181 (model-1), and P211 (model-2) of CD147, as well as introducing mutations P180A-G181A and P211A individually in each model. All systems were studied using accelerated molecular dynamics simulations and the molecular mechanics generalized Born surface area (MM/GBSA) method. For model-0, CypA bound to the ectodomain of CD147 with the highest binding affinity. Moreover, mutations P180A-G181A of CD147 in model-0 decreased the binding affinity and weakened the dynamic correlation between CD147 and CypA, which resulted in CypA shifting from the initial binding location. Other residue mutations of CD147 did not significantly affect the CD147-CypA binding, as reflected by the energy and structural analyses. Compared with surface plasmon resonance results and nuclear magnetic resonance shift signals, CypA should tend to reciprocally bind to the groove of CD147, and the binding process might be modulated by P180-G181 rather than P211. Besides, residue R201 of CD147 is critical for CD147-CypA binding and needs further experimental verification. These findings further our understanding of the recruitment between CD147 and CypA and its potential role in the development of inflammation and viral infection. [ABSTRACT FROM AUTHOR]

The search for efficient, stable, and low-cost electrocatalysts toward the water splitting and oxygen reduction reaction (ORR) in acidic media is of great significance to develop renewable energies, but remains an ongoing challenge. Herein, by employing large-scale density functional theory computations, we demonstrate that atomically dispersed bi-atom catalysts (BACs) could act as a versatile design platform to achieve efficient electrochemical hydrogen evolution reaction (HER), oxygen reduction reaction (OER), and ORR activity. Through regulating bi-atom combinations on a g-CN substrate, a materials genome containing 26 homonuclear and 253 heteronuclear BACs (M2/g-CN and MIMII/g-CN) is built. Eight, one and three BACs go beyond the activity benchmark of Pt(111) and IrO2(110) surfaces and have excellent performance for the HER, OER, and ORR, respectively. Especially, PdNi/g-CN and AgPt/g-CN exhibit a negligible potential barrier for the HER. AuRh/g-CN shows a small overpotential of 0.35 V for the ORR. AgPd/g-CN has promising bifunctional activity for both the OER and ORR with small overpotentials of 0.43 and 0.48 V respectively. AuCo/g-CN reveals tremendous trifunctional activities (with an overpotential of 0.05 V for the HER, 0.52 V for the OER, and 0.48 V for the ORR). A kinetic simulation further verifies their catalytic performance. Finally, a machine-learning technique is employed to establish the internal relationship between the HER/OER/ORR, and identify the key characteristic factors that govern the catalytic performance including the geometry parameters of the M–M–N6 (MI–MII–N6) moiety. This work not only provides a comprehensive view of BACs for water splitting and the ORR, but also presents a new path for designing and searching for efficient BACs toward electrochemical reactions. [ABSTRACT FROM AUTHOR]

p38α mitogen-activated protein kinase (MAPK) undergoes autophosphorylation induced by the binding of TGFβ-activated kinase 1 binding protein 1 (TAB1) in myocardial ischemia. Investigation of the conformational transformations in p38α triggered by TAB1 binding is motivated by the need to find selective p38α activation inhibitors to treat myocardial ischemia. Herein, the conformational transformations of p38α were studied via all-atom accelerated molecular dynamics simulations and principal component analysis. With the binding of TAB1, the conformational changes of p38α auto-activation were characterized by the movement of the activation loop (A-loop) away from the αG helix toward the αF, αE helixes and L16-loop. In addition, a diverse intermediate state with an extensional and phosphorylated A-loop different from the transition intermediate state was explored. The conformational changes, including the A-loop alpha-structure breaking and the stronger hydrogen bond network formation, are accompanied by the extension of the A-loop and more intramolecular interactions in p38α. TAB1 correlates with other regions of p38α that are distal from the TAB1-binding site, including the A-loop, αC helix, and L16-loop, which regulates the intramolecular correlation of p38α. And, the phosphorylation further enhances the correlations between the A-loop and the other regions of p38α. The correlation results imply the regulation process of p38α conformational transformations. These findings will improve our understanding of the autophosphorylation of kinase and facilitate the development of selective inhibitors for the treatment of ischemic injury. [ABSTRACT FROM AUTHOR]

In spintronics, the embodiment of abundance availability, long spin relaxation time, complete spin-polarization and high Curie temperature (TC) in intrinsic metal-free half-metallic ferromagnets (MFHMFs) are highly desirable and challenging. In this work, employing density functional theory, we first propose a dynamically, thermally, and mechanically stable two-dimensional (2D) intrinsic MFHMF, i.e. a MoS2-like PN2 monolayer, which possesses not only completely spin-polarized half-metallicity, but also an above-room-temperature TC (385 K). The half-metallic gap is calculated to be 1.70 eV, which can effectively prevent the spin–flip transition caused by thermal agitation. The mechanism of magnetism in the PN2 monolayer is mainly derived from the p electron direct exchange interaction that separates from usual d-state magnetic materials. Moreover, the robustness of the ferromagnetism and half-metallicity is observed against an external strain and carrier (electron or hole) doping. Surprisingly, electron doping can effectively increase the Curie temperature of the PN2 monolayer. The proposed research work provides an insight that PN2 can be a promising candidate for realistic room-temperature metal-free spintronic applications. [ABSTRACT FROM AUTHOR]

GaSb nanowires integrated on a silicon-based substrate are of great significance for p-type field-effect transistors. In particular, chips are becoming more and more miniaturized, and complicated dielectric engineering needs to be avoided. Therefore, the introduction of junction field-effect transistor (JFET) can be used to improve the performance of transistors. We demonstrated a heterostructure p-channel depletion type GaSb junction field-effect transistor by combining with n-WS2 sheets. Typical diode characteristics are observed in n-WS2/p-GaSb heterostructure diodes, with a high rectification ratio of ∼104. The JFET has excellent electrical features with an ON/OFF ratio of ∼104 and the sub-threshold swing (SS ≈ 723 mV dec−1). With the back gate control the ON/OFF current ratio is improved to ∼106 and the low SS is restrained to 166 mV dec−1. Moreover, due to the electrical properties of the heterojunction the JFET and p–n diodes maintain good stability at high temperatures. Therefore, the WS2/GaSb heterojunction enables the miniaturization of an integrated power electronic system and provides a promising route to low power electronics. [ABSTRACT FROM AUTHOR]

The electrical contacts at the van der Waals (vdW) interface between two-dimensional (2D) semiconductors and metal electrodes could dramatically affect the device performance. Herein, we construct a series of graphene (Gr)/XC (X = P, As, Sb, and Bi) vdW heterostructures, in which XC monolayers have aroused considerable attention recently as an emerging class of 2D semiconductors. The electronic structures and contact properties of Gr/XC vdW heterostructures are investigated systematically using first-principles calculations. The band structures indicate that both Gr/PC and Gr/AsC heterostructures form n-type Schottky contacts with Schottky barrier heights (SBHs) of 0.01 eV and 0.43 eV, respectively, while both Gr/SbC and Gr/BiC heterostructures preferably form Ohmic contacts. The different X atoms result in different work functions, electron flows, charge distributions and orientations of the dipole moment in Gr/XC heterostructures. Moreover, the tunneling probabilities increase with the increasing atom radius of X from P to Bi, indicating the most improved current and smaller contact resistance at the interfaces of Gr/BiC compared to Gr/PC, Gr/AsC and Gr/SbC heterostructures. Our work could provide meaningful information for designing high-performance nanoelectronic devices based on Gr/XC heterostructures. [ABSTRACT FROM AUTHOR]

In the present study, a functionalized carboxymethyl cellulose-based adsorbent (PEI–PAM–CMC) was prepared via linking polyethyleneimine and polyacrylamide with carboxymethyl cellulose by epichlorohydrin. It possessed a sponge-like structure with a large number of micron-sized pores, which facilitated the mass transfer of Cr(VI). Under neutral conditions, Cr(VI) can be efficiently removed by the protonated PEI–PAM–CMC. The residual levels in the effluent were below 0.5 and 0.05 mg L−1 for 10 and 1 mg L−1 of Cr(VI), respectively. The adsorption data fitted well with the pseudo-second order kinetic model and Langmuir isotherm. Common ions including Cl−, H2PO4−, NO3−, K+, Na+, Ca2+, Mg2+ and Cr3+ had neglectable influence for Cr(VI) adsorption on the PEI–PAM–CMC except SO42−. Meanwhile, PEI–PAM–CMC showed good regeneration and reusability with a 7.5% decrease in the removal rate after ten adsorption/desorption cycles. XPS analysis and DFT calculation revealed that Cr(VI) uptake by the PEI–PAM–CMC was involved in electrostatic attraction and chemical binding. Electrostatics and induction were the main weak interaction between Cr(VI) and the adsorbent, and the major chemical adsorption sites were mainly distributed in the nitrogen groups. This research not only developed an efficient material for Cr(VI) removal but also provided a promising insight into an adsorption mechanism study. [ABSTRACT FROM AUTHOR]

Emerging two-dimensional (2D) noble-metal dichalcogenide (NMDC) PdX2 (X = S and Se) materials crystallize in an unusual orthorhombic structure (2O phase) with unique pentagons and PdX4 planar squares as building blocks, and have attracted tremendous attention in recent years for their novel physical and chemical properties, as well as promising applications in the future. Motivated by the attractive properties and encouraging applications of PdX2 materials, we explore the 2O phase NMDC material PdSSe using particle swarm optimization algorithms combined with first-principles calculations. We not only uncover three stable low-energy bulk phases, but also predict two polymorphs of the 2D monolayer exfoliated from the bulk phases, exhibiting mechanical, dynamic, and thermal stabilities. Due to its novel puckered pentagonal structure, the PdSSe monolayer exhibits flexible mechanical properties with anisotropic Young's modulus and Poisson's ratio. The bandgaps of the two polymorphs of the 2D pentagonal PdSSe monolayer are 2.10 and 2.06 eV, and their band-edges perfectly straddle the redox potential of water. Furthermore, these materials possess excellent light absorption in the visible and ultraviolet regions, and the absorption coefficients reach the order of 106 cm−1. More importantly, the predicted materials exhibit highly desirable carrier mobilities and anisotropy, which can promote the separation of the photogenerated electrons and holes, and effectively reduce the probability of recombination, thus remarkably promoting photocatalytic water splitting. These excellent properties enable PdSSe monolayers as candidate materials for promising applications in high-performance optoelectronic and nanoelectronic devices. The predicted unconventional properties of PdSSe not only supply a meaningful complement to the fascinating NMDC materials of PdSe2 and PdS2, but also will attract extensive interest from a wide audience to explore unanticipated properties and design new functional devices based on PdSSe. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 has recently caused an epidemic in humans and poses a huge threat to global public health. As a primary receptor of SARS-CoV-2, angiotensin-converting enzyme 2 (ACE2) exists in different hosts that are in close contact with humans, especially cats and dogs. However, the underlying mechanism of how the spike receptor binding domain (RBD) of SARS-CoV-2 cooperates with human ACE2 (hACE2), cat ACE2 (cACE2) and dog ACE2 (dACE2) and the variation in binding remains largely unsolved. Therefore, we explored the binding behavior of the spike RBD with cACE2, dACE2 and hACE2 via all-atom molecular dynamics simulations. In accordance with the binding free energies and residue interactions, the spike RBD has respective binding specificities with cACE2, dACE2 and hACE2, and the binding affinities decrease in the order of hACE2, cACE2, dACE2, mainly due to changes in the amino acids Q24L, H34Y, and M82T in cACE2 or dACE2. Furthermore, alanine scanning analysis results validated some key residues of the spike RBD interact with ACE2 and provided clues to the variation of amino acid that could influence the transmissibility or immune responses of SARS-CoV-2. Decreasing dynamic correlations strengths of ACE2 with the RBD were found in all hACE2–RBD, cACE2–RBD and dACE2–RBD systems. The ACE2 protein shows variable motion modes across the zinc metallopeptidase domain, which induces different interactions between ACE2 and the RBD. Our studies reveal that the motion pattern of the zinc metallopeptidase domain is critical to the binding behavior of RBD with ACE2. These findings could aid our understanding of selective recognition involving various ACE2 with the SARS-CoV-2 spike and shed further light on the binding mechanisms. [ABSTRACT FROM AUTHOR]

The role of interfaces in facilitating the growth of conventional 1D nanostructures is well established. Apparently, the presence of interfaces is also decisive in the growth of 2D transition metal dichalcogenides, but their role remains ambiguous. Here, we show that the molten Na–Nb–O liquid precursor would create microscale vapor–liquid and liquid–solid interfaces, which determine the nucleation and growth of large single-crystal monolayer 2D metallic NbS2 by vapor–liquid–solid (VLS) method. We discover that reaction and growth are separated at the vapor–liquid interface and the liquid–solid interface, respectively, due to the insolubility between S and the liquid precursor. The vapor–liquid interface reaction reduces the concentration of NbSx monomers in droplets, thus effectively controlling the nucleation density. The liquid–solid interface lowers the diffusion barrier of NbS2 monomers, which increases the growth rate. We establish a 2D diffusion model and calculate and conclude that the growth rate in VLS mode is approximately 8 times that in vapor–solid (VS) mode, which is consistent with our experimental results. This finding reveals that two interfaces are the determining factors that control the nucleation and growth of large NbS2 single crystals, which will likely contribute to the development of the wafer-scale growth of 2D materials for further device applications. [ABSTRACT FROM AUTHOR]

A Li+-doping strategy is a promising route for achieving highly efficient Cu2ZnSn(S,Se)4 (CZTSSe) photovoltaic devices with a large grain absorber layer, high p-type carrier concentration and good band alignment at the Cu2ZnSn(S,Se)4/CdS interface. However, Li+-doped CZTSSe solar cells based on in situ and pre-deposition doping strategies reported thus far generally suffer from massive lithium losses and sodium rejection due to the soda-lime glass substrate. Therefore, simultaneously fulfilling the goals of simple and efficient Li+-doping remains a major technical challenge, which may be addressed, as we demonstrate here, with the development of a Se&LiF co-selenization process. By engineering the band alignment of the Cu2ZnSn(S,Se)4/CdS interface through the Se&LiF co-selenization process, an encouraging efficiency of 11.63% with an open-circuit voltage deficit of 0.583 V has been reached. Furthermore, the crystallinity of the absorber layer and the distribution of copper are improved, and a more copper-poor CZTSSe surface is formed. This novel Li+-doping strategy introduces a new approach towards the goal of high-performance CZTSSe solar cells compatible with a simple manufacturing process and excellent performance. [ABSTRACT FROM AUTHOR]

All-inorganic halide perovskites have made significant achievements in electronics, optoelectronics, and other fields due to their unique physical and chemical properties. However, the researchers focus on the traditional planar field-effect transistors, which have limited electrical performance and applications due to their planar structure with a long channel length. Here, we report a vertical field-effect transistor (VFET) based on the CsPbBr3 microplatelet grown by van der Waals epitaxial growth. The VFET is achieved by a direct evaporation method utilizing the height difference between the CsPbBr3 single-crystal and the graphene substrate. Compared with the traditional planar structure transistors, the device exhibits more excellent performance, such as a high current density of 12.3 A cm−2 and a high on/off ratio over 106 at room temperature. The trap-state density of the CsPbBr3 single-crystal is calculated to be as low as 2.3 × 1015 cm−3 by space-charge-limited currents, which further proves its excellent crystallinity. Also, we have firstly fabricated a MoS2/CsPbBr3 heterostructure inverter with a vertical structure, which could implement the "No" function in logic operations. This work opens a new pathway for practical application of all-inorganic halide perovskites in future electronics. [ABSTRACT FROM AUTHOR]

Restacking of 2D nanomaterials is often deemed to be detrimental to their applications. In contrast to this common notion, here we demonstrate that tightly packed stacked MoS2 exhibits a higher electrocatalytic activity for hydrogen evolution than the more loosely stacked ones. [ABSTRACT FROM AUTHOR]

Since graphene has been successfully exfoliated, two-dimensional (2D) materials constitute a vibrant research field and open vast perspectives in high-performance applications. Among them, bismuthene and 2D bismuth (Bi) are unique with superior properties to fabricate state-of-the-art energy saving, storage and conversion devices. The largest experimentally determined bulk gap, even larger than those of stanene and antimonene, allows 2D Bi to be the most promising candidate to construct room-temperature topological insulators. Moreover, 2D Bi exhibits cyclability for high-performance sodium-ion batteries, and the enlarged surface together with the good electrochemical activity renders it an efficient electrocatalyst for energy conversion. Also, the air-stability of 2D Bi is better than that of silicene, germanene, phosphorene and arsenene, which could enable more practical applications. This review aims to thoroughly explore the fundamentals of 2D Bi and its improved fabrication methods, in order to further bridge gaps between theoretical predictions and experimental achievements in its energy-related applications. We begin with an introduction of the status of 2D Bi in the 2D-material family, which is followed by descriptions of its intrinsic properties along with various fabrication methods. The vast implications of 2D Bi for high-performance devices can be envisioned to add a new pillar in energy sciences. In addition, in the context of recent pioneering studies on moiré superlattices of other 2D materials, we hope that the improved manipulation techniques of bismuthene, along with its unique properties, might even enable 2D Bi to play an important role in future energy-related twistronics. [ABSTRACT FROM AUTHOR]

Ultraviolet-B (UV-B, 290–320 nm) photons in the solar spectrum are essential for the generation of vitamin D, which plays an essential role in the absorption of calcium in the human body. However, excess UV-B irradiation can also induce diseases, such as erythema or skin cancer. Thus, the quantitative detection of UV-B is indispensable maximizing the advantages of this wavelength range. In general, due to scattering in the atmosphere, the UV-B signal that reaches the earth's surface is always too weak to detect. Here, we report a photodetector based on solution-processed ZnGa2O4 truncated octahedral microparticles, which exhibit a sensitive response to UV-B photons in the air, while not responding to UV-A or visible photons. An outstanding performance in accurate detection of a weak UV-B photon signal of 31.8 nW cm−2 with detectivity of ＞4 × 1014 Jones is achieved. To our knowledge, this is the first demonstration for the accurate detection of UV-B radiation at such low intensity. Other figures of merit in our photodetector, including high Ion/Ioff ratio of ＞104 and low noise current of ∼2 × 10−14 A Hz−1/2, confirm the promising application of our detector in quantitative detection of UV-B photons in ambient or applied conditions for biological or medical applications. [ABSTRACT FROM AUTHOR]

Downsizing alloy anode materials has been demonstrated as an efficient strategy to alleviate volume expansion and prolong the cycling performance for lithium (Li) ion storage. However, dimension and size dependent Li-ion diffusion and battery performances have scarcely been explored. This work was carried out to determine the tailored engineering required to create a natural layered material, β-phase antimony (Sb), and identify the dimension and size effects on the Li ion storage performance, which is of particular interest for alloy anode materials at present. Two types of tailored engineering, in the vertical direction and omnidirectional, were adopted to produce few layer antimonene and Sb nanoparticles (NPs) using ultrasonication regulation. In the absence of helpful fluoroethyl carbonate additives, tailored engineering can still improve the cycling stability and the reversible capacity, and the lateral size dominated two-dimensional (2D) antimonene exhibits a higher rate performance than Sb NPs. In situ electron microscopy analysis reveals the limited expansion of the lateral size for 2D antimonene upon lithiation. Theoretical simulation reveals that the in-plane diffusion energy barrier (0.25 eV) for layered β-phase Sb is much smaller than the diffusion energy barrier across its interlayers (1.14 eV). Therefore, the unique 2D antimonene with large lateral size can achieve better high rate performance than Sb NPs, and also has stable capacity for Li ion storage. [ABSTRACT FROM AUTHOR]

Two-dimensional dichalcogenides (2D TMDCs) have emerged as a class of materials that may impact on future nanoelectronic and optoelectronic technologies. Design and discovery of new TMDC materials with reduced dimensionality is a significant and particularly interesting subject. Here, we proposed a new 2D layered structure material PdSe2 realized via high pressure by first-principles simulations. We found PdSe2 undertaking structural phase transitions under pressure, from the monoclinic phase with a space group of I2/a to two similar 2D layered structure phases with monoclinic C2/m and hexagonal P3̅m1 space groups at 4.5 GPa and 17.5 GPa, respectively. Interestingly, a new type of 2D monolayer material PdSe2 can be cleaved from the monoclinic C2/m bulk phase, suggested by the small exfoliation energy of 33.85 meV Å−2 (0.54 J m−2). More importantly, the new 2D PdSe2 monolayer is not only confirmed to be both dynamically and thermally stable, but also possesses a moderate band gap of about 1.10 eV and excellent visible-light optical absorption, suitable for photovoltaic applications. Furthermore, the effective masses and carrier mobility of the electrons and holes display extraordinary anisotropy along different transport directions, indicating that the monoclinic monolayer PdSe2 is a promising 2D material to facilitate effective electron/hole separation in high-performance nanoelectronic devices. [ABSTRACT FROM AUTHOR]

In this paper, we precisely controlled the d-spacing of vertically aligned MoS2 arrays ranging from 6.2 to 10 Åvia heating-controlled deintercalation of NH4+ ions. The finely controllable interlayer nanoarchitecture resulted in an optimal d-spacing of 7.3 Å, which on nitrogenous reduced graphene oxide (N-RGO) delivered a reversible capacity of 295 mA h g−1 after 2000 cycles at 1 A g−1 for Na+ intercalation. [ABSTRACT FROM AUTHOR]

Inspired by the recent experimental realization of pnictogen–silicon analogues of benzene and great interest in silicene, phosphorene and their heavier counterparts, herein we designed three planar porous 2D nanomaterials, namely porous silaphosphorene (pSiP), silaarsenene (pSiAs) and silaantimonene (pSiSb), and systematically investigated their stability, and electronic and optical properties, as well as their potential as photocatalysts for water splitting. Porous silaphosphorene, silaarsenene and silaantimonene monolayers are all thermodynamically, dynamically and thermally stable, and the aromaticity in each six-membered Si3P3/Si3As3/Si3Sb3 ring plays an important role in their enhanced stability. They are all semiconductors with direct band gaps of 1.93, 1.57 and 0.95 eV (HSE06) and have comparable carrier mobility to MoS2. Their good stability and exceptional electronic and optical properties make them promising candidates for applications in solar cells and other optoelectronics fields. Moreover, the suitable band edge alignments of pSiP and pSiAs monolayers endow them with potential applications as photocatalysts for water splitting. [ABSTRACT FROM AUTHOR]

Phosphorene, an emerging two-dimensional material, has received considerable attention due to its layer-controlled direct bandgap, high carrier mobility, negative Poisson's ratio and unique in-plane anisotropy. As cousins of phosphorene, 2D group-VA arsenene, antimonene and bismuthene have also garnered tremendous interest due to their intriguing structures and fascinating electronic properties. 2D group-VA family members are opening up brand-new opportunities for their multifunctional applications encompassing electronics, optoelectronics, topological spintronics, thermoelectrics, sensors, Li- or Na-batteries. In this review, we extensively explore the latest theoretical and experimental progress made in the fundamental properties, fabrications and applications of 2D group-VA materials, and offer perspectives and challenges for the future of this emerging field. [ABSTRACT FROM AUTHOR]

The enhanced photocatalytic mechanisms for the hybrid AlN/MX2 (MX2 = MoSe2, WS2, and WSe2) nanocomposites are systematically investigated by density-functional-theory calculations. Our theoretical calculations study the photocatalytic performance of AlN/MX2 nanocomposites with the inclusion of the spin–orbit coupling (SOC) effect. The results demonstrate that the band gaps of the AlN/MX2 bilayers vary from 1.72 to 1.93 eV, covering the main region of the visible light. All of the AlN–MX2 bilayers exhibit prominent visible and UV light response compared to their individual constituents, implying their potential applications as excellent light-absorbers. The AlN–MX2 heterobilayers are excellent photocatalysts for splitting water into hydrogen due to the perfect fit of band edge positions with respect to water reduction and oxidation potentials. Particularly, AlN–WS2 has type-II band alignment. Besides, the applied small biaxial tensile strain can not only effectively tune the band edge positions, but can also trigger an indirect–direct band gap transition in AlN–MX2 bilayers maintaining the excellent optical properties. Therefore, the strained AlN–MX2 bilayers are expected to be more promising candidates for photocatalysis. Overall, our theoretical predictions point toward the prospective future of novel AlN–MX2 heterostructures for photocatalysis. [ABSTRACT FROM AUTHOR]

Photothermal therapy is regarded as one of the most promising cancer treatment technologies due to its negligible side effects and fast operation. However, its therapeutic efficacy is still limited by the lack of cost-effective photostable and biocompatible therapeutic agents with efficient light absorption in the biological window. Here, taking MoO2 as an example, we propose oxide nanocrystals (NCs), with both a metallic electronic structure and near-infrared (NIR) plasmon resonance, for efficient, stable and biocompatible photothermal cancer therapy. Monoclinic MoO2 NCs with good crystallinity were fabricated through the combination of laser ablation in liquid and solvothermal synthesis. The as-synthesized NCs showed intensive local surface plasmon resonance (LSPR) absorption at 800–1000 nm, the NIR biological window, due to their metallic electronic structure and oxide dielectric function. This unique NIR LSPR characteristic leads to excellent photothermal performance, i.e., the maximum temperature elevation was found to be up to 37.5 °C with a MoO2 NC concentration of 0.05 mg mL−1 under 808 nm laser irradiation. Moreover, MoO2 solution is highly photostable, as it exhibits stable irradiation-induced temperature elevation of about 14.3 °C even after four temperature elevation cycles. As a photothermal therapy agent against 4T1 cancer cells, MoO2 NCs exhibit not only good biocompatibility, but also excellent tumor inhibition effects. The highest inhibition rate was up to 80.45%, and the average tumor volume was 2.73 times smaller than normal growth 14 days after the treatment. The results prove that MoO2 NCs exhibiting NIR LSPR can act as an effective agent for photothermal cancer therapy with great photostability and biocompatibility. [ABSTRACT FROM AUTHOR]