At present the most successful rechargeable battery is the Li-ion battery, due to the small size, high energy density, and low reduction potential of Li. Computational materials science has become an increasingly important tool to study these batteries, and in particular cathode properties. In silico studies of cathode materials have proven to be a valuable tool to understand the workings of cathodes, without having to do sophisticated experiments. First-principles and empirical computations have been used by various groups to study key properties, such as structural stability, electronic structure, ion diffusion mechanisms, equilibrium cell voltage, thermal and electrochemical stability, and surface behavior of Li-ion battery cathode materials. Arguably, the most practical and promising Li-ion cathode materials today are layered oxide materials, and in particular LiNi 1−x−y Co x Mn y O 2 (NCM) and LiNi 1−x−y Co x Al y O 2 (NCA). Here, some of the computational approaches to studying Li-ion batteries, with special focus on issues related to layered materials, are discussed. Subsequently, an overview of theoretical and related experimental work performed on layered cathode materials, and in particular on NCM and NCA materials, is provided.

An enduring impediment in the photocatalysis domain is the rapid recombination of photoinduced charge carriers. One viable strategy to realize efficient separation of photoinduced charge carriers is to design core/shell nanostructures. In this context, our work explains the substantial separation of photocarriers and enhanced light harvesting in TiO 2 nanostructures following the realization of core/shell geometry with CuS. We demonstrate the design of the TiO 2 /CuS core/shell nanostructures, utilizing a surface-functionalizing agent, 3-mercaptopropionic acid, and offering commendable visible light driven photocatalytic performance for degradation of virulent organic pollutants of dye wastewater, like methylene blue (MB). To validate the merits of the TiO 2 /CuS core/shell nanostructures, we have also designed TiO 2 /CuS composite nanostructures under similar conditions (without utilizing the surface-functionalizing agent, 3-mercaptopropionic acid). Successful realization of TiO 2 /CuS nanostructures (core/shell and composite) was concluded from the PXRD, FESEM, TEM, HRTEM, EDS elemental mapping, and DRS studies. The resulting core/shell nanostructures have propitious photocatalytic performance (∼90%) over composite nanostructures (∼58%), which could be scrutinized in terms of core/shell geometry, maximizing the interfacial contact between TiO 2 and CuS and enabling retardation in the recombination rate of the photoinduced charge carriers by confining electrons mainly in one component (core) and holes in the other component (shell).To have the best photocatalytic performance from the TiO 2 /CuS core/shell nanostructures, we also determined the optimum amount of photocatalyst (0.3 g/L) and organic pollutant dye concentration (0.003 g/L) required for visible light driven degradation of MB. A credible mechanism of the charge transfer process and mechanism of photocatalysis supported from trapping experiments in the TiO 2 /CuS nanostructures for the degradation of an aqueous solution of MB is also explicated. Degradation intermediates analysis performed using mass spectroscopy (MS) studies showed that MB dye degradation is initiated by a demethylation pathway. Our work also highlights the stability and recyclability of a core/shell nanostructures photocatalyst and supports its potential for environmental applications. We thus anticipate that our results bear broad potential in the photocatalysis domain for the design of a visible light functional and reusable core/shell nanostructures photocatalyst.

The antimicrobial activities of zirconia (ZrO2) nanoparticles and zirconium mixed ligand complexes were studied on bacterial strains of E. coli, S. aureus and fungal strain of A. niger. The nanoparticles of zirconia and Zr(IV) complexes with different amino acids as ligands were synthesized by hydrothermal method. X-ray diffraction (XRD) and HRTEM confirmed the crystalline nature and morphology of the synthesized products. The antimicrobial studies revealed that the zirconia exhibits activity only against the E. coli, whereas, the Zr(IV) complexes exhibits activity against both the bacteria: gram -ve E. coli and gram +ve S. aureus as well as fungal strains. The Zr(IV) complexes are found to possess significant antifungal activity against A. niger. The results are indicative of crystal plane-dependent antimicrobial activity of zirconia nanoparticles and complexes. The observed difference in the antibacterial activity of ZrO2 crystals and Zr(IV) complexes may be ascribed to the atomic arrangements of different exposed surfaces. On the basis of the study, it could be speculated that the ZrO2 nanoparticles with the same surface areas but with different shapes i.e., different active facets will show different antimicrobial activity.

Band gap engineering offers tunable optical and electronic properties of semiconductors in the development of efficient photovoltaic cells and photocatalysts. Our study demonstrates the band gap engineering of ZnO nanorods to develop a highly efficient visible-light photocatalyst. We engineered the band gap of ZnO nanorods by introducing the core/shell geometry with Ag2S sensitizer as the shell. Introduction of the core/shell geometry evinces great promise for expanding the light-harvesting range and substantial suppression of charge carrier recombination, which are of supreme importance in the realm of photocatalysis. To unveil the superiority of Ag2S as a sensitizer in engineering the band gap of ZnO in comparison to the Cd-based sensitizers, we also designed ZnO/CdS core/shell nanostructures having the same shell thickness. The photocatalytic performance of the resultant core/shell nanostructures toward methylene blue (MB) dye degradation has been studied. The results imply that the ZnO/Ag2S core/shell nanostructures reveal 40- and 2-fold enhancement in degradation constant in comparison to the pure ZnO and ZnO/CdS core/shell nanostructures, respectively. This high efficiency is elucidated in terms of (i) efficient light harvesting owing to the incorporation of Ag2S and (ii) smaller conduction band offset between ZnO and Ag2S, promoting more efficient charge separation at the core/shell interface. A credible photodegradation mechanism for the MB dye deploying ZnO/Ag2S core/shell nanostructures is proposed from the analysis of involved active species such as hydroxyl radicals (OH(•)), electrons (e(-)(CB)), holes (h(+)(VB)), and superoxide radical anions (O2(•-)) in the photodegradation process utilizing various active species scavengers and EPR spectroscopy. The findings show that the MB oxidation is directed mainly by the assistance of hydroxyl radicals (OH(•)). The results presented here provide new insights for developing band gap engineered semiconductor nanostructures for energy-harvesting applications and demonstrate Ag2S to be a potential sensitizer to supersede Cd-based sensitizers for eco-friendly applications.

We report on highly Mn-doped GaAs nanowires (NWs) of high crystalline quality fabricated by ion beam implantation, a technique that allows doping concentrations beyond the equilibrium solubility limit. We studied two approaches for the preparation of Mn-doped GaAs NWs: First, ion implantation at room temperature with subsequent annealing resulted in polycrystalline NWs and phase segregation of MnAs and GaAs. The second approach was ion implantation at elevated temperatures. In this case, the single-crystallinity of the GaAs NWs was maintained, and crystalline, highly Mn-doped GaAs NWs were obtained. The electrical resistance of such NWs dropped with increasing temperature (activation energy about 70 meV). Corresponding magnetoresistance measurements showed a decrease at low temperatures, indicating paramagnetism. Our findings suggest possibilities for future applications where dense arrays of GaMnAs nanowires may be used as a new kind of magnetic material system.

We report on temperature-dependent charge transport in heavily doped Mn(+)-implanted GaAs nanowires. The results clearly demonstrate that the transport is governed by temperature-dependent hopping processes, with a crossover between nearest neighbor hopping and Mott variable range hopping at about 180 K. From detailed analysis, we have extracted characteristic hopping energies and corresponding hopping lengths. At low temperatures, a strongly nonlinear conductivity is observed which reflects a modified hopping process driven by the high electric field at large bias.

Solar light harvesting and conversion to useful energy are the most important tasks for overcoming the world energy crisis. The design of advanced materials for solar light conversion requires focused research to obtain efficient photocatalytic systems. Photogenerated charge carrier separation is a crucial prerequisite in applications such as photo‐electrochemical water splitting, photovoltaics, and photocatalytic dye degradation. Interfacial charge‐transfer (IFCT) plays a significant role in electron–hole separation considering the energy barriers of the energy levels at semiconductor–semiconductor, semiconductor–metal, semiconductor–molecule, and semiconductor–electrolyte interfaces. Both electron and hole transport across the interface via IFCT, with comparable rates, are important for maintaining enhanced photocatalytic efficiency and stability of the catalysts. The key focus of this article is to understand the charge transfer processes at the interface and the relationship between photogenerated charge separation and photocatalytic activity. The interfacial charge transfer in different interfaces is discussed, along with the fundamentals of IFCT in photo‐electrochemical processes; semiconductor heterojunctions with materials having proper band alignment and offer new ways to design multifunctional photocatalysts are also disucssed. The charge transfer process from semiconductor to catalyst molecules and dye molecules to semiconductor is explained in detail.

We report on low-temperature magnetotransport and SQUID measurements on heavily doped Mn-implanted GaAs nanowires. SQUID data recorded at low magnetic fields exhibit clear signs of the onset of a spin-glass phase with a transition temperature of about 16 K. Magnetotransport experiments reveal a corresponding peak in resistance at 16 K and a large negative magnetoresistance, reaching 40% at 1.6 K and 8 T. The negative magnetoresistance decreases at elevated temperatures and vanishes at about 100 K. We interpret our transport data in terms of spin-dependent hopping in a complex magnetic nanowire landscape of magnetic polarons, separated by intermediate regions of Mn impurity spins, forming a paramagnetic/spin-glass phase.