Dual functionality of the BiN monolayer: unraveling its photocatalytic and piezocatalytic water splitting properties.

To achieve scalable and economically viable green hydrogen (H2) production, the photocatalytic and piezocatalytic processes are promising methods. The key to successful overall water splitting (OWS) for H2 production in these processes is using suitable semiconductor catalysts with appropriate band edge potentials, efficient optical absorption, higher mechanical flexibility, and piezoelectric coefficients. Thus, we explore the bismuth nitride (BiN) monolayer using density functional theory simulations, revealing intriguing catalytic properties. The BiN monolayer is a semiconductor with an indirect electronic bandgap (Eg) of 2.08 eV and displays excellent visible light absorption (approximately 105 cm-1). Detailed analyses show that the band edges satisfy the redox potential for photocatalytic OWS via biaxial strain engineering and pH variation. Notably, the solar to hydrogen conversion efficiency (ηSTH) for the BiN monolayer can reach 17.18%, which exceeds the 10% efficiency limit of photocatalysts for economical green H2 production. The obtained in-plane piezoelectric coefficient of e11 = 16.18 ŠC m-1 is superior to widely studied 2D materials. Moreover, the generated piezopotential under oscillatory strain stands at 28.34 V, which can initiate the water redox reaction via the piezocatalytic mechanism. This originates from the mechanical flexibility coupled with higher piezoelectric coefficients. The result highlights the BiN monolayer's potential application in photocatalytic, piezocatalytic, and photo-piezo-catalytic OWS.

Intrinsic ferroelectricity and large bulk photovoltaic effect in novel two-dimensional buckled honeycomb-like lattice of NbP: first-principles study.

Using first-principles calculations, we predict that the two-dimensional (2D) monolayers of NbP with the buckled honeycomb-like and puckered tetragonal structure can be obtained from the (110) and (001) orientations, respectively, of its bulk crystal structure. The electronic properties of these monolayers are spectacularly different as tetragonal lattice is metallic whereas the honeycomb-like lattice (h-NbP) is a semiconductor and exhibits intrinsic ferroelectricity originating from a raresd2-sp2hybridization. The shift current bulk photovoltaic effect (BPVE) is systematically investigated in the h-NbP monolayer (1.21 Å thickness) using the Wannier interpolation method. Strong absorption of visible light at ∼2 eV and a large 3D shift current of ∼180µA V-2is obtained which is attributed to the partial delocalization of Bloch states due tosd2-sp2hybridization. We compare the shift current response of h-NbP monolayer with that of some previously reported bulk ferroelectrics and 2D monolayers, suggesting that h-NbP monolayer can yield a large shift current at an ultimate thickness and is a promising 2D material for the BPVE application under the visible light. Strain effect is also investigated, revealing that the h-NbP monolayer is dynamically stable up to a strain limit of ±3%, and the shift current increases by ∼9% at a compressive strain of -3% as the Bloch states are more delocalized due to the strengthening ofsd2-sp2hybridization. The results presented in this study can pave the paths to fabricate the 2D monolayered structures of NbP, and realize the BPVE based next-generation solar cells of h-NbP monolayer.

Anodic formation of thick anatase TiO2 mesosponge layers for high-efficiency photocatalysis.

We report a process for the fabrication of an anatase TiO(2) mesosponge (TMS) layer by an optimized Ti anodization process in a hot glycerol electrolyte followed by a suitable etching process. Such layers can easily be grown to >10 microm thickness and have regular channels and structural features in the 5-20 nm range. The layers show high photocatalytic activity and are mechanically very robust. The layers therefore open new pathways to the wide field of TiO(2)(anatase) applications.

Effective La-Na Co-Doped TiO2 Nano-Particles for Dye Adsorption: Synthesis, Characterization and Study on Adsorption Kinetics.

The mesoporous La-Na co-doped TiO2 nanoparticles (NPs) have been synthesized by non-aqueous, solvent-controlled, sol-gel route. The substitutional doping of large sized Na+1 and La+3 at Ti4+ is confirmed by X-ray diffraction (XRD) and further supported by Transmission Electron Microscopy (TEM) and X-ray Photo-electron Spectroscopy (XPS). The consequent increase in adsorbed hydroxyl groups at surface of La-Na co-doped TiO2 results in decrease in pHIEP, which makes nanoparticle surface more prone to cationic methylene blue (MB) dye adsorption. The MB dye removal was examined by different metal doping, pH, contact time, NPs dose, initial dye concentration and temperature. Maximum dye removal percentage was achieved at pH 7.0. The kinetic analysis suggests adsorption dynamics is best described by pseudo second-order kinetic model. Langmuir adsorption isotherm studies revealed endothermic monolayer adsorption of Methylene Blue dye.

Strain engineering of ferroelectric KNbO3 for bulk photovoltaic applications: an insight from density functional theory calculations.

A large ferroelectric (FE) polarization and low bandgap are essential to improving the bulk photovoltaic response which is the generation of photocurrent in the polar non-centrosymmetric materials such as FE perovskite oxides. Among various perovskite oxides, Potassium Niobate (KNbO3, KNO) is a promising FE material for bulk photovoltaic applications as its bandgap and polarization can be tuned effectively by strain, doping, or by applying an electric field. In this work, using the density functional theory calculations, we present an insight into the strain engineering of polarization, band structure, and optical properties of the cubic (C), tetragonal (T), and orthorhombic (O) structures of KNO. The tensile and compressive strain under the triaxial, biaxial, and uniaxial conditions are applied along the direction parallel and perpendicular to the polar axis of KNO structures. We find that the bandgap decreases along with a substantial increment of polarization on the application of tensile strain along the direction parallel to the polar axis. In T (O) phase at +2% strain, the polarization increases by 18 µC cm-2 (14 µC cm-2) in triaxial, 26 µC cm-2 (16 µC cm-2) in biaxial, and 29 µC cm-2 (29 µC cm-2) in uniaxial conditions with a considerable decreasing of bandgap with respect to zero strain condition. Therefore, wisely applying the tensile strain along the direction parallel to the polar axis, the photovoltaic efficiency of KNO can be improved.

Extraintestinal Infections Caused by Non-toxigenic Vibrio cholerae non-O1/non-O139.

Vibrio cholerae is an aerobic, sucrose fermentative Gram-negative bacterium that generally prevails in the environment. Pathogenic V. cholerae is well-known as causative agent of acute diarrhea. Apart from enteric infections, V. cholerae may also cause other diseases. However, their role in causing extraintestinal infections is not fully known as it needs proper identification and evaluation. Four cases of extraintestinal infections due to V. cholerae non-O1/non-O139 have been investigated. The isolates were screened for phenotypic and genetic characteristics with reference to their major virulence genes. Serologically distinct isolates harbored rtx, msh, and hly but lacked enteric toxin encoding genes that are generally present in toxigenic V. cholerae. Timely detection of this organism can prevent fatalities in hospital settings. The underlying virulence potential of V. cholerae needs appropriate testing and intervention.

The effects of post-processing on the surface and the optical properties of copper indium sulfide quantum dots.

In the current contribution we report on investigations regarding the surface of CuInS2 quantum dots and on different strategies to control the amount of surface ligands in a post-processing step. In particular, the reactivity of the organic components, that is, 1-dodecanthiol and 1-octadecene as ligand and solvent, respectively, during nanocrystal formation was studied. A new method to remove residuals from the reaction mixture and to detach excess organics from the surface of the nanocrystals is reported. Our new method, which is based on the utilization of acids, is compared with standard purification procedures by means of thermogravimetric analysis (TGA) with particular focus on its efficiency to remove organics. As a complement, the surface chemistry is analyzed by nuclear magnetic resonance spectroscopy (NMR) to shed light on the nature of the organic components still present after purification. Further analysis of the product by inductively coupled plasma optical emission spectroscopy (ICP-OES) is performed to verify the influence of the new purification method on surface composition and properties. Moreover, steady state and time resolved spectroscopies give insights into excitonic behavior as well as recombination processes. Finally, the new method is optimized for the purification of CuInS2-ZnS nanocrystals, which show enhanced optical properties.

Microstructure and properties of well-ordered multiferroic Pb(Zr,Ti)O(3)/CoFe(2)O(4) nanocomposites.

A nanofabrication technique combining pulsed laser deposition and a nanoporous anodic aluminum oxide membrane mask is being proposed to prepare various types of multiferroic nanocomposites, viz. periodically ordered CoFe(2)O(4) dots covered by a continuous Pb(Zr,Ti)O(3) layer, Pb(Zr,Ti)O(3) dots covered with CoFe(2)O(4), and Pb(Zr,Ti)O(3)/CoFe(2)O(4) bilayer heterostructure dots. By properly tuning the processing parameters, epitaxial nanodot-matrix composites can be obtained. For the composite consisting of CoFe(2)O(4) nanostructures covered by a Pb(Zr,Ti)O(3) film, an unexpected out-of-plane magnetic easy axis induced by the top Pb(Zr,Ti)O(3) layer and a uniform microdomain structure can be observed. The nanocomposites tested by piezoresponse force microscopy (PFM) exhibit strong piezoelectric signals, and they also display magnetoelectric coupling revealed by magnetic-field dependent capacitance measurement.