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Magnesium–Sulfur batteries are one of most appealing options among the post‐lithium battery systems due to its potentially high energy density, safe and sustainable electrode materials. The major practical challenges are originated from the soluble magnesium polysulfide intermediates and their shuttling between the electrodes, which cause high overpotentials, low sulfur utilization, and poor Coulombic efficiency. Herein, a functional Mo6S8 modified separator is designed to effectively address these issues. Both the experimental results and density functional theory calculations show that the electrochemically active Mo6S8 layer has a superior adsorption capability of polysulfides and simultaneously acts as a mediator to accelerate the polysulfide conversion kinetics. Remarkably, the magnesium–sulfur cell assembled with the functional separator delivers a high specific energy density (942.9 mA h g−1 in the 1st cycle) and can be cycled at 0.2 C for 200 cycles with a Coulombic efficiency of 96%. This work demonstrates a new design concept toward high‐performance metal–sulfur batteries. [ABSTRACT FROM AUTHOR]

Ultrafast, light-induced dynamics in copper–zinc–tin–sulfide (CZTS) photovoltaic nanoparticles are investigated through a combination of optical and x-ray transient absorption spectroscopy. Laser-pump, x-ray-probe spectroscopy on a colloidal CZTS nanoparticle ink yields element-specificity, which reveals a rapid photo-induced shift of electron density away from Cu-sites, affecting the molecular orbital occupation and structure of CZTS. We observe the formation of a stable charge-separated and thermally excited structure, which persists for nanoseconds and involves an increased charge density at the Zn sites. Combined with density functional theory calculations, the results provide new insight into the structural and electronic dynamics of CZTS absorbers for solar cells. [ABSTRACT FROM AUTHOR]

The structure of the electrolyte is crucial for the performance of rechargeable magnesium batteries. Doubly charged cations interact much stronger with both anions and solvent molecules, forming different size clusters. Here, we apply DFT calculations to investigate salt solvation by altering the first solvation shell of the magnesium‐chloride complexes in different ethereal solvents: tetrahydrofuran, monoglyme, diglyme, triglyme and tetraglyme. The analysis was performed by looking for the most stable structures, considering mono‐, di‐ and trimeric clusters of MgxCly. The determination of clusters geometries, together with their energies, resulted in a comprehensive picture of the thermodynamically preferred state of the electrolyte, and allowed for a simple assessment of the electrochemical activity of the electrolyte. Our analysis shows that clustering is beneficial for desolvation of magnesium from the cluster, but causes overpotentials due to hindered electron transfer. [ABSTRACT FROM AUTHOR]

The development of multivalent metal (such as Mg and Ca) based battery systems is hindered by lack of suitable cathode chemistry that shows reversible multi‐electron redox reactions. Cationic redox centres in the classical cathodes can only afford stepwise single‐electron transfer, which are not ideal for multivalent‐ion storage. The charge imbalance during multivalent ion insertion might lead to an additional kinetic barrier for ion mobility. Therefore, multivalent battery cathodes only exhibit slope‐like voltage profiles with insertion/extraction redox of less than one electron. Taking VS4 as a model material, reversible two‐electron redox with cationic–anionic contributions is verified in both rechargeable Mg batteries (RMBs) and rechargeable Ca batteries (RCBs). The corresponding cells exhibit high capacities of >300 mAh g−1 at a current density of 100 mA g−1 in both RMBs and RCBs, resulting in a high energy density of >300 Wh kg−1 for RMBs and >500 Wh kg−1 for RCBs. Mechanistic studies reveal a unique redox activity mainly at anionic sulfides moieties and fast Mg2+ ion diffusion kinetics enabled by the soft structure and flexible electron configuration of VS4. [ABSTRACT FROM AUTHOR]

Highlights • Understanding the different phases of TaO x and their electrical characteristics is essential in memristor devices but also for a wider range of other applications. • So far there is no detailed work about the correlation between the oxygen partial pressure during deposition using PLD, the exact composition of TaO x thin films and the electrical properties. • Here, we investigated the relation between the oxygen partial pressure and the chemical and physical properties of the film. Abstract Tantalum oxide has a wide range of applications and has drawn much attention especially for its useful properties in resistive random-access memories, in which the Ta oxide composition plays an important role to control the electrical properties of the TaO x thin films. In this paper, we present a way to tune the composition of TaO x thin films by varying the oxygen partial pressure during growth using pulsed laser deposition. TaO x thin films were deposited at room temperature, under oxygen partial pressures ranging from 10−6 mbar to 2 × 10−2 mbar. Using angle resolved X-ray photoelectron spectroscopy, we show that the composition of the film varies systematically with the oxygen partial pressure during the film growth. We then correlate the oxygen content with the electrical properties of the film and the results show that the composition has a great influence on the resistivity of the TaO x thin films. As the oxygen partial pressure during deposition increases, the percentage of tantalum pentoxide (Ta 2 O 5) as well as the resistivity of the films increases. This experimental approach provides a pathway to control the TaO x thin film stoichiometry and its electrical properties during growth. [ABSTRACT FROM AUTHOR]

The two-dimensional metal forming at the interface between an oxide insulator and SrTiO3 provides new opportunities for oxide electronics. However, the quantum Hall effect, one of the most fascinating effects of electrons confined in two dimensions, remains underexplored at these complex oxide heterointerfaces. Here, we report the experimental observation of quantized Hall resistance in a SrTiO3 heterointerface based on the modulation-doped amorphous-LaAlO3/SrTiO3 heterostructure, which exhibits both high electron mobility exceeding 10,000 cm²/V s and low carrier density on the order of ~1012 cm-2. Along with unambiguous Shubnikov-de Haas oscillations, the spacing of the quantized Hall resistance suggests that the interface is comprised of a single quantum well with ten parallel conducting two-dimensional sub-bands. This provides new insight into the electronic structure of conducting oxide interfaces and represents an important step towards designing and understanding advanced oxide. [ABSTRACT FROM AUTHOR]