Theoretical investigation of Janus Ti2BST (T = O, Se) monolayers as anode materials for Na/K-ion batteries.

The structures, stability, and electrochemical performances of Janus Ti2BST (T = O, Se) monolayers as anode materials for Na/K-ion batteries (NIBs/KIBs) are investigated by first-principles calculations. The results demonstrate that Ti2BST monolayers are mechanically, dynamically, and thermally stable. The electronic structures display good conductivity. Moreover, the low diffusion barriers of 0.107/0.039 eV (0.111/0.063 eV) for Na/K indicate that the Ti2BSO (Ti2BSSe) monolayer has excellent rate performance for NIBs/KIBs. Low average open circuit voltages (OCVs) (0.322-0.439 V) can produce a high voltage in NIBs/KIBs. Meanwhile, little structural changes during charge/discharge ensure great cycle stability. Especially, the Ti2BSO monolayer has a high theoretical capacity of 691.64/537.75 mA h g-1 for NIBs/KIBs. The outstanding performances demonstrate that the Ti2BST monolayers are potential anode materials for NIBs/KIBs.

miRNA-200c-3p deficiency promotes epithelial-mesenchymal transition in triple-negative breast cancer by activating CRKL expression.

Epithelial-mesenchymal transition (EMT) plays an important role in malignant progression of Triple-negative breast cancer (TNBC). Many studies have confirmed that miRNA-200c-3p is related to EMT. And we found that it is involved in the regulation of EMT, but the exact mechanism is unclear. CRKL is highly expressed in a variety of tumors and plays a role in EMT. In this study, the potential targets of miRNA-200c-3p were searched in miRPathDB, Targetscan and PicTar. And there are 68 potential targets at the intersection of the three databases. Then, bioinformatics and text mining performed by Coremine Medica, and found that among 68 potential targets, CRKL has the strongest correlation with EMT in TNBC. Therefore, we speculated that miRNA-200c-3p involvement in EMT might be related to CRKL. To verify miRNA-200c-3p inhibits the malignant phenotype of TNBC by regulating CRKL, RT‒PCR, western blotting, Clonal formation assays,CCK-8 proliferation assays, transwell invasion assays, Luciferase reporter assay and nude mouse transplantation tumor assay were performed. In this study, we found that miRNA-200c-3p is under-expressed and EMT-related genes are up-regulated in TNBC, and miRNA-200c-3p can inhibit cancer cell proliferation, invasion and the expression of EMT-related genes and proteins in TNBC. Further research confirmed that miRNA-200c-3p could inhibit EMT by inhibiting the expression of CRKL that directly combining CRKL gene.

S-scheme NiO/C3N5 heterojunctions with enhanced interfacial electric field for boosting photothermal-assisted photocatalytic H2 and H2O2 production.

Heterostructured visible-light-responsive photocatalysts represent a prospective approach to achieve efficient solar-to-chemical energy conversion. Herein, we propose a facile self-assembly technique to synthesize NiO nanoparticles/C3N5 nanosheets (NOCN) heterojunctions for hydrogen (H2) evolution catalysis and hydrogen peroxide (H2O2) production under visible light. In this regard, the black NiO nanoparticles (NPs) were tightly anchored on the surface of C3N5 nanosheets (CNNS) to construct S-scheme NOCN heterojunction, enabling efficient charge separation and high redox capability. Obtained results elucidated that the incorporated NiO NPs significantly promote light-harvesting efficiency and photo-to-thermal capacity over the NOCN composites. The enhanced photothermal effect facilitates the charge carrier transfer rate across the heterojunction and boosts the surface reaction kinetics. Accordingly, the photocatalytic performances of CNNS for H2 release and H2O2 production can be manipulated by introducing NiO NPs. The modified photocatalytic properties of NOCN composites are ascribed to the synergistic effects of all integrated components and the S-scheme heterojunction formation. Impressively, the high H2 evolution photocatalysis efficiency of NOCN nano-catalysts in seawater certifies their potential environmental applicability. Among all, the 12-NOCN nano-catalyst exhibits a higher photocatalytic efficiency for H2 release (112.2 µmol∙g-1∙h-1) and H2O2 production (91.2 µmol∙L-1∙h-1). Besides, the 12-NOCN nano-catalyst reveals excellent recyclability and structural stability. Additionally, the possible mechanism for photothermal-assisted photocatalysis is proposed. This work affords a feasible pathway to design photothermal-assisted S-scheme heterojunctions for diverse photocatalytic applications.

Bioinspired 1T-MoS2-based aerogel beads for efficient freshwater harvesting in harsh environments.

Freshwater scarcity is one of the most critical issues worldwide, particularly in arid regions, stemming from population growth and climate change. Inspired by the hydrophilic bump structures of desert beetles, 1T-MoS2-based aerogel beads with porous structures and CaCl2-crystal loading (termed as MoAB-m@CaCl2-n) were prepared for freshwater harvesting. Metallic-phase MoS2 nanospheres exhibit excellent photothermal conversion abilities, facilitating solar-driven water desorption and evaporation. Owing to the synergistic effect of its localized surface features, hydrophilic groups, and dispersive CaCl2 particles, MoAB-2@CaCl2-2 efficiently harvests water from atmosphere with a superior moisture adsorption capacity (0.18-0.82 g g-1) at a wide range of relative humidity (10 %-70 %). Under one-sun illumination, MoAB-2@CaCl2-2 demonstrates an outstanding solar-driven water evaporation rate of 2.25 kg m-2h-1. The water evaporation rate from soil (water content = 20 %) is 1.19 kg m-2h-1, which is sufficient for sustainable freshwater generation from the soil in arid regions. More importantly, the multifunctional MoAB-2@CaCl2-2-based homemade freshwater generation prototype delivers a certain amount of water harvesting (0.99 g g-1 day-1) on a rainy day and provides an impressive daily freshwater yield (53.7 kg m-2) under natural sunlight. The integrated device exhibits excellent efficiency and practicality and offers a feasible method for freshwater harvesting in harsh environments.

ROS-Responsive Bola-Lipid Nanoparticles as a Codelivery System for Gene/Photodynamic Combination Therapy.

The nonviral delivery systems that combine genes with photosensitizers for multimodal tumor gene/photodynamic therapy (PDT) have attracted much attention. In this study, a series of ROS-sensitive cationic bola-lipids were applied for the gene/photosensitizer codelivery. Zn-DPA was introduced as a cationic headgroup to enhance DNA binding, while the hydrophobic linking chains may facilitate the formation of lipid nanoparticles (LNP) and the encapsulation of photosensitizer Ce6. The length of the hydrophobic chain played an important role in the gene transfection process, and 14-TDZn containing the longest chains showed better DNA condensation, gene transfection, and cellular uptake. 14-TDZn LNPs could well load photosensitizer Ce6 to form 14-TDC without a loss of gene delivery efficiency. 14-TDC was used for codelivery of p53 and Ce6 to achieve enhanced therapeutic effects on the tumor cell proliferation inhibition and apoptosis. Results showed that the codelivery system was more effective in the inhibition of tumor cell proliferation than individual p53 or Ce6 monotherapy. Mechanism studies showed that the production of ROS after Ce6 irradiation could increase the accumulation of p53 protein in tumor cells, thereby promoting caspase-3 activation and inducing apoptosis, indicating some synergistic effect. These results demonstrated that 14-TDC may serve as a promising nanocarrier for gene/PDT combination therapy.

Exploring the structural, electronic, and hydrogen storage properties of hexagonal boron nitride and carbon nanotubes: insights from single-walled to doped double-walled configurations.

This study investigates the structural intricacies and properties of single-walled nanotubes (SWNT) and double-walled nanotubes (DWNT) composed of hexagonal boron nitride (BN) and carbon (C). Doping with various atoms including light elements (B, N, O) and heavy metals (Fe, Co, Cu) is taken into account. The optimized configurations of SWNT and DWNT, along with dopant positions, are explored, with a focus on DWNT-BN-C. The stability analysis, employing binding energies, affirms the favorable formation of nanotube structures, with DWNT-C emerging as the most stable compound. Quantum stability assessments reveal significant intramolecular charge transfer in specific configurations. Electronic properties, including charge distribution, electronegativity, and electrical conductivity, are examined, showcasing the impact of doping. Energy gap values highlight the diverse electronic characteristics of the nanotubes. PDOS analysis provides insights into the contribution of atoms to molecular orbitals. UV-Vis absorption spectra unravel the optical transitions, showcasing the influence of nanotube size, dopant type, and location. Hydrogen storage capabilities are explored, with suitable adsorption energies indicating favorable hydrogen adsorption. The desorption temperatures for hydrogen release vary across configurations, with notable enhancements in specific doped DWNT-C variants, suggesting potential applications in high-temperature hydrogen release. Overall, this comprehensive investigation provides valuable insights into the structural, electronic, optical, and hydrogen storage properties of BN and C nanotubes, laying the foundation for tailored applications in electronics and energy storage.

Promising sensors for pharmaceutical pollutant adsorption using Clar's goblet-based 2D membranes.

This study focuses on the design of new 2D membranes from connected Clar's Goblet as a potential sensor for pharmaceutical pollutants, specifically the painkiller drugs aspirin, paracetamol, ibuprofen, and diclofenac. The electronic, optical, and interaction properties are investigated using density functional theory calculations. The Clar's Goblet membranes (CGMs) that were chosen are semiconductors with an energy gap of around 1.5 eV, according to energy gap calculations and density of states. Molecular electrostatic potential (ESP) analysis shows that CGMs have electrophilic and nucleophilic sites, suggesting their suitability for interacting with pharmaceutical pollutants. The adsorption energies confirm the chemical adsorption of pharmaceutical pollutants with diclofenac showing the strongest adsorption. The UV-Vis absorption spectra of CGMs-drug complexes are analyzed, revealing a redshift compared to the absorption spectrum of CGMs alone, confirming the adsorption of these drugs. Further analysis using hole/electron examinations indicates that the type of excitation is local excitation rather than charge transfer excitation. This study quantitatively characterized hole and electron distribution in excited states using various indices. The analysis revealed local excitation transitions and significant charge transfer between the CGMs molecule and pharmaceutical pollutants. Additionally, non-covalent interaction analysis indicates the presence of van der Waals interactions, highlighting the adsorption behavior of the drugs. These results demonstrate the potential of CGMs as a highly sensitive sensor for pharmaceutical pollutants.

A photothermal MoS2 decorated biomass carbon-based aerogel with a directionally aligned porous structure for mitigating heavy metal stress under seawater acidification.

Marine animals and human are threatened by seawater acidification and metal contamination. Especially, the toxicity of copper (Cu) is expected to be boosted with seawater acidification. However, studies on the removal of Cu under seawater acidification are limited for practical applications, owing to obstacles such as instability, secondary contamination, and low adsorption efficiency. In this work, coconut shells were utilized for the synthesis of biomass carbon, which was then decorated with MoS2. A novel porous MoS2/carbon-based aerogel (MCA) with the synergistic effect of photothermal conversion and adsorption was constructed via directional freeze-drying technology. The adsorption properties of MCA were a precise match with Freundlich isotherm and pseudo-second-order kinetic models with a high correlation coefficient (R2) of more than 0.995. Under solar illumination, the surface temperature of MCA reached up to 36.3 °C and the adsorption capacity of MCA increased to 833.8 mg g-1, indicating that the remarkable thermal properties of MCA contributed to achieving high adsorption capacity. The adsorption mechanisms of MCA involved in the removal of Cu(ii) ions were dominated by chemisorption rather than surface physical adsorption. Owing to its outstanding photothermal conversion performance and directionally aligned porous structure, MCA was able to remove Cu(ii) species from seawater, and the adsorption ability of MCA reached 247.1 mg g-1 after ten adsorption cycles. MCA exhibited excellent stability to resist the complex natural environment and was easy to reuse. Overall, MCA with a series of merits, including high adsorption efficiency, excellent photothermal conversion property, and outstanding cycling stability, was confirmed to contribute to addressing heavy metal stress under seawater acidification.

Exploring the Potential of Chemically Modified Graphyne Nanodots as an Efficient Adsorbent and Sensitive Detector of Environmental Contaminants: A First Principles Study.

In this study, we investigated the reactivity of γ-graphyne (Gp) and its derivatives, Gp-CH3, Gp-COOH, Gp-CN, Gp-NO2, and Gp-SOH, for the removal of toxic heavy metal ions (Hg+ 2, Pb+ 2, and Cd+ 2) from wastewater. From the analysis of the optimized structures, it was observed that all the compounds exhibited planar geometry. The dihedral angles (C9-C2-C1-C6 and C9-C2-C1-C6) were approximately 180.00°, indicating planarity in all molecular arrangements. To understand the electronic properties of the compounds, the HOMO (EH) and LUMO (EL) energies were calculated, and their energy gaps (Eg) were determined. The EH and EL values ranged between - 6.502 and - 8.192 eV and - 1.864 and - 3.773 eV, respectively, for all the compounds. Comparing the EH values, Gp-NO2 exhibited the most stable HOMO, while Gp-CH3 had the least stable structure. In terms of EL values, Gp-NO2 had the most stable LUMO, while Gp-CH3 was the least stable. The Eg values followed the order: Gp-NO2 < Gp-COOH < Gp-CN < Gp-SOH < Gp-CH3 < Gp, with Gp-NO2 (4.41 eV) having the smallest energy gap. The density of states (DOS) analysis showed that the shape and functional group modifications affected the energy levels. Functionalization with electron-withdrawing (CN, NO2, COOH, SOH) or electron-donating (CH3) groups reduced the energy gap. To specifically target the removal of heavy metal ions, the Gp-NO2 ligand was selected for its high binding energy. Complexes of Gp-NO2-Cd, Gp-NO2-Hg, and Gp-NO2-Pb were optimized, and their properties were analyzed. The complexes were found to be planar, with metal-ligand bond distances within the range of 2.092→3.442 Å. The Gp-NO2-Pb complex exhibited the shortest bond length, indicating a stronger interaction due to the smaller size of Pb+ 2. The computed adsorption energy values (Eads) indicated the stability of the complexes, with values ranging from - 0.035 to -4.199 eV. Non-covalent interaction (NCI) analysis was employed to investigate intermolecular interactions in Gp-NO2 complexes. The analysis revealed distinct patterns of attractive and repulsive interactions, providing valuable insights into the binding preferences and steric effects of heavy metals.

CaCu3Mn2Te2O12: An Intrinsic Ferrimagnetic Insulator Prepared Under High Pressure.

CaCu3Mn2Te2O12 was synthesized using high-temperature and high-pressure conditions. The compound possesses an A- and B site ordered quadruple perovskite structure in Pn3̅ symmetry with the charge combination of CaCu32+Mn22+Te26+O12. A ferrimagnetic phase transition originating from the antiferromagnetic interaction between A' site Cu2+ and B site Mn2+ ions is found to occur at TC ≈ 100 K. CaCu3Mn2Te2O12 also shows insulating electric conductivity. Optical measurement demonstrates the energy bandgap to be about 1.9 eV, in agreement with the high B site degree of chemical order between Mn2+ and Te6+. The first-principles theoretical calculations confirm the Cu2+(↓)-Mn2+(↑) ferrimagnetic coupling as well as the insulating nature with an up-spin direct bandgap. The current CaCu3Mn2Te2O12 provides an intriguing example of an intrinsic ferrimagnetic insulator with promising applications in advanced spintronic devices.

Electronic and optical properties of chemically modified 2D GaAs nanoribbons.

We employed density functional theory calculations to investigate the electronic and optical characteristics of finite GaAs nanoribbons (NRs). Our study encompasses chemical alterations including doping, functionalization, and complete passivation, aimed at tailoring NR properties. The structural stability of these NRs was affirmed by detecting real vibrational frequencies in infrared spectra, indicating dynamical stability. Positive binding energies further corroborated the robust formation of NRs. Analysis of doped GaAs nanoribbons revealed a diverse range of energy gaps (approximately 2.672 to 5.132 eV). The introduction of F atoms through passivation extended the gap to 5.132 eV, while Cu atoms introduced via edge doping reduced it to 2.672 eV. A density of states analysis indicated that As atom orbitals primarily contributed to occupied molecular orbitals, while Ga atom orbitals significantly influenced unoccupied states. This suggested As atoms as electron donors and Ga atoms as electron acceptors in potential interactions. We investigated excited-state electron-hole interactions through various indices, including electron-hole overlap and charge-transfer length. These insights enriched our understanding of these interactions. Notably, UV-Vis absorption spectra exhibited intriguing phenomena. Doping with Te, Cu, W, and Mo induced redshifts, while functionalization induced red/blue shifts in GaAs-34NR spectra. Passivation, functionalization, and doping collectively enhanced electrical conductivity, highlighting the potential for improving material properties. Among the compounds studied, GaAs-34NR-edg-Cu demonstrated the highest electrical conductivity, while GaAs-34NR displayed the lowest. In summary, our comprehensive investigation offers valuable insights into customizing GaAs nanoribbon characteristics, with promising implications for nanoelectronics and optoelectronics applications.

Interfacial engineering of Ti3C2 MXene/CdIn2S4 Schottky heterojunctions for boosting visible-light H2 evolution and Cr(VI) reduction.

Developing efficient heterojunction photocatalysts that have a high charge carrier separation rate and improved light-harvesting capacity is a crucial step in solving energy crisis and reducing environmental pollution. Herein, we synthesized few-layered Ti3C2 MXene sheets (MXs) by a manual shaking process, and combined with CdIn2S4 (CIS) to construct novel Ti3C2 MXene/CdIn2S4 (MXCIS) Schottky heterojunction through a solvothermal method. The strong interface between two-dimensional (2D) Ti3C2 MXene and 2D CIS nanoplates led to enhanced light-harvesting capacity and promoted charge separation rate. Additionally, the presence of S vacancies on the MXCIS surface helped to trap free electrons. The optimal sample, 5-MXCIS (with 5 wt% MXs loading), exhibited outstanding performance for photocatalytic hydrogen (H2) evolution and Cr(VI) reduction under visible light due to the synergistic effect of enhanced light-harvesting capacity and charge separation rate. The charge transfer kinetics was thoroughly studied using multiple techniques. The reactive species of •O2-, •OH and h+ were generated in 5-MXCIS system, and e- and •O2- radicals were found to be the main contributors to Cr(VI) photoreduction. Based on the characterization results, a possible photocatalytic mechanism for H2 evolution and Cr(VI) reduction was proposed. On the whole, this work provides new insights into the design of 2D/2D MXene-based Schottky heterojunction photocatalysts for boosting photocatalytic efficiency.

All-Weather Freshwater and Electricity Simultaneous Generation by Coupled Solar Energy and Convection.

Integrating solar evaporation-driven desalination and electricity production has emerged as a promising approach to alleviate energy crisis and freshwater scarcity. However, there remain huge challenges to achieve high water productivity and steady power generation efficiency. Herein, a compact evaporation-induced water-electricity co-generation device was proposed using a bio-waste squid ink sphere-based cellulose fabric as an evaporator and a silicon nanowires array-based evaporation-driven moist-electric generator. The efficient localized solar thermal heating of the photothermal component leads to significant enhancement in freshwater yield, and the latent heat of vapor condensation is recycled to promote the electricity generation. More notably, the device is capable of harvesting wind energy toward all-weather water and power generation. The fabricated device demonstrated a high evaporation rate of 2.17 kg m-2 h-1 with a collection rate of 66.7% and a maximum output voltage of 1.48 V under one sun illumination with a wind speed of 4 m s-1. The outdoor experiments display a maximum water evaporation rate of 1.84 kg m-2 h-1 with a maximum output voltage of 1.35 V even on cloudy days. Such superior performance of a comprehensive device has great potential for sustainable and practical application in freshwater and electricity generation.

Remarkably Enhanced Red Upconversion Emission in ß-NaLuF4:Er,Tm Microcrystals via Ion Exchange.

Internal OH- defects always cause significant depletion of excitation energy for low upconversion efficiency; however, preventing the incorporation of OH- into the crystal lattice is very difficult during the synthesis of upconversion crystals. In this work, red upconversion emission is dramatically enhanced in Er3+-sensitized hexagonal NaLuF4 (ß-NaLuF4) microcrystals through a collaborative effect of ion exchange and Tm3+ doping. The ion exchange can not only maintain the morphology very well but also strongly reduce the internal OH- defects, which can enhance the upconversion luminescence due to improved excitation energy harvesting and red to green (R/G) ratio due to intense cross-relaxation. Doping of Tm3+ as an energy trapping center not only regulates the red emission output but also reduces the excitation energy loss. ß-NaLuF4:Er,Tm microcrystals after ion exchange exhibit stronger red upconversion emission compared with ß-NaYF4:Er,Tm and ß-NaGdF4:Er,Tm counterparts. Moreover, fluorescent labeling of the fingerprint pattern printed from ß-NaLuF4:Er,Tm microcrystals with stable and intense red fluorescence has been demonstrated under 980 nm excitation.

Modulation of the lipophilicity and molecular size of thiosemicarbazone inhibitors to regulate tyrosinase activity.

A group of 5-methylsalicylaldehyde thiosemicarbazone derivatives (HMTs) bearing different lipophilic and steric substituents attached at the 3-position of cresol ring were synthesized and investigated as mushroom tyrosinase (TYR) inhibitors. The ability of HMTs to inhibit the diphenolase activity of TYR was evaluated with L-DOPA as substrate by determining IC50 values in relation to their structure modifications. HMTs displayed distinct inhibitory competencies towards TYR activity with IC50 values in the range of 1.02-143.56 µM. A close correlation between their inhibition potency and both lipophilicity and molecular size was observed. The inhibitory effect of the hydroxyethyl-containing derivatives was much higher than the hydroxyethyl-free ones overall. Among them, HMT-NBO exhibited the most potent effect with IC50 of 5.85 µM, which was nearly 25-fold and 3.8-fold lower than its parent HMT-NBE and the control kojic acid, respectively. The hydroxyethyl clearly benefited the improvement of the inhibitory competences and acted as a regulating group of lipophilicity of the inhibitors. The kinetic analyses showed that HMTs were reversible and mixed type inhibitors against mushroom TYR. The inhibition mechanism was studied by means of fluorescence spectroscopy, FT-IR, ESI-MS and molecular docking analysis. The results indicated that the observed inhibitory effect of HMTs was accomplished by acting on the amino acid residues rather than by chelating the centre copper ions of TYR. Each of HMTs can insert the hydrophobic pocket and interact with the residues of TYR through Van der Waals forces and hydrogen bonds, with additional electrostatic interactions for HMT-NEE and HMT-NEO further strengthening the affinity. Meanwhile, the inhibitors were observed to bind with L-DOPA or/and L-DOPAquinone forming 1:1 stoichiometric complexes, probably exerting indirect inhibition against TYR activity.

Chiral Majorana edge modes and vortex Majorana zero modes in superconducting antiferromagnetic topological insulator.

The antiferromagnetic topological insulator (AFTI) is topologically protected by the combined time-reversal and translational symmetryTc. In this paper we investigate the effects of thes-wave superconducting pairings on the multilayers of AFTI, which breaksTcsymmetry and can realize quantum anomalous Hall insulator with unit Chern number. For the weakly coupled pairings, the system corresponds to the topological superconductor (TSC) with the Chern numberC= ±2. We answer the following questions whether the local Chern numbers and chiral Majorana edge modes of such a TSC distribute around the surface layers. By the numerical calculations based on a theoretic model of AFTI, we find that when the local Chern numbers are always dominated by the surface layers, the wavefunctions of chiral Majorana edge modes must not localize on the surface layers and show a smooth crossover from spatially occupying all layers to only distributing near the surface layers, similar to the hinge states in a three dimensional second-order topological phases. The latter phase, denoted by the hinged TSC, can be distinguished from the former phase by the measurements of the local density of state. In addition we also study the superconducting vortex phase transition in this system and find that the exchange field in the AFTI not only enlarges the phase space of topological vortex phase but also enhances its topological stability. These conclusions will stimulate the investigations on superconducting effects of AFTI and drive the studies on chiral Majorana edge modes and vortex Majorana zero modes into a new era.

In Situ Modulation of A-Site Vacancies in LaMnO3.15 Perovskite for Surface Lattice Oxygen Activation and Boosted Redox Reactions.

Modulation of A-site defects is crucial to the redox reactions on ABO3 perovskites for both clean air application and electrochemical energy storage. Herein we report a scalable one-pot strategy for in situ regulation of La vacancies (VLa ) in LaMnO3.15 by simply introducing urea in the traditional citrate process, and further reveal the fundamental relationship between VLa creation and surface lattice oxygen (Olatt ) activation. The underlying mechanism is shortened Mn-O bonds, decreased orbital ordering, promoted MnO6 bending vibration and weakened Jahn-Teller distortion, ultimately realizing enhanced Mn-3d and O-2p orbital hybridization. The LaMnO3.15 with optimized VLa exhibits order of magnitude increase in toluene oxidation and ca. 0.05 V versus RHE (reversible hydrogen electrode) increase of half-wave potential in oxygen reduction reaction (ORR). The reported strategy can benefit the development of novel defect-meditated perovskites in both heterocatalysis and electrocatalysis.

Two-dimensional quantum dots for highly efficient heterojunction solar cells.

The electronic and optical properties of finite silicene, graphene, and arsenene heterostructures are investigated using first principles calculations. The optoelectronic properties of these structures are precisely controlled, by chemical functionalization, shape, and size, to produce suitable donor energy gap and minimal conduction band offset that enable the construction of efficient heterojunction solar cells. Heterojunctions with only Van der Waals interactions between layers have been achieved in functionalized silicene/graphene and arsenene/graphene. The distribution of the highest occupied/lowest unoccupied molecular orbital on donor/acceptor layer in addition to the contribution of each layer into the total electronic density of states insure that the only interlayer interaction is the van der Waals one and charge separation is attained. The heterojunctions have donors' energy gaps ranging from 1.2 to 1.8 eV which in conjunction with the very low conduction band offset ∼ 0.002 eV enable the building of type-II solar cells with extremely high power conversion efficiency up to 23.34%. The prominent low energy optical excitations are mainly contributed by a transition from donor molecular orbitals to acceptor ones. Therefore, functionalized 2D heterojunctions are excellent candidates for building ultrathin, stable, and low-cost efficient solar cells.

Fast 3D-lithium-ion diffusion and high electronic conductivity of Li2MnSiO4 surfaces for rechargeable lithium-ion batteries.

High theoretical capacity, high thermal stability, the low cost of production, abundance, and environmental friendliness are among the potential attractiveness of Li2MnSiO4 as a positive electrode (cathode) material for rechargeable lithium-ion batteries. However, the experimental results indicated poor electrochemical performance in its bulk phase due to high intrinsic charge transfer resistance and capacity fading during cycling, which limit its large-scale commercial applications. Herein, we explore the surface stability and various lithium-ion diffusion pathways of Li2MnSiO4 surfaces using the density functional theory (DFT) framework. Results revealed that the stability of selected surfaces is in the following order: (210) > (001) > (010) > (100). Moreover, the Wulff-constructed equilibrium shape revealed that the Li2MnSiO4 (001) surface is the most predominant facet, and thus, preferentially exposed to electrochemical activities. The Hubbard-corrected DFT (DFT + U, with U = 3 eV) results indicated that the bulk insulator with a wide band gap (E g = 3.42 eV) changed into narrow electronic (E g = 0.6 eV) when it comes to the Li2MnSiO4 (001) surface. Moreover, the nudged elastic band analysis shows that surface diffusion along the (001) channel was found to be unlimited and fast in all three dimensions with more than 12-order-of-magnitude enhancements compared with the bulk system. These findings suggest that the capacity limitation and poor electrochemical performance that arise from limited electronic and ionic conductivity in the bulk system could be remarkably improved on the surfaces of the Li2MnSiO4 cathode material for rechargeable lithium-ion batteries.

Ultrathin Z-scheme 2D/2D N-doped HTiNbO5 nanosheets/g-C3N4 porous composites for efficient photocatalytic degradation and H2 generation under visible light.

To realize highly efficient utilization of solar energy for solving problems of environmental pollution and energy shortage has attracted increasing attention. Herein, a two-step exfoliation-restacking process was employed to construct ultrathin Z-scheme two-dimensional (2D)/2D N-doped HTiNbO5 nanosheets/g-C3N4 (RTCN) heterojunction composites with the increased specific surface areas, showing the enhanced photocatalytic performance for rhodamine B (RhB) degradation and hydrogen (H2) generation under visible light irradiation. A 2D/2D heterojunction structure was formed between N-doped H+-restacked HTiNbO5 nanosheets (N-RTNS) and g-C3N4, which was beneficial for the effectively spatial separation of photogenerated charge carriers. The improved photocatalytic activities may be attributed to the synergistic effects of the increased specific surface area, N-doping and 2D/2D heterostructure. The active species of holes (h+), hydroxyl (•OH) and superoxide (•O2-) radicals contributed to RhB photodegradation. A Z-scheme photocatalytic mechanism was proposed over RTCN-2 composite, showing dual advantages of the highly redox ability and efficient charge carrier separation.