In Situ Lattice-Resolution Revelation of the Origins of Unexplored Anisotropic Sodiation Kinetics and Phase Transition in the Niobium Sulfide Anode.

Layered transition metal dichalcogenides (TMDs) have exhibited huge potential as anode materials for sodium-ion batteries. Most of them usually store sodium via an intercalation-conversion mechanism, but niobium sulfide (NbS) may be an exception. Herein, through in situ transmission electron microscopy, we carefully investigated the insertion behaviors of Na ions in NbS and directly visualized anisotropic sodiation kinetics.

A 2D-0D-2D Sandwich Heterostructure toward High-Performance Room-Temperature Gas Sensing.

The construction of two-dimensional (2D) van der Waals (vdW) heterostructures over black phosphorus (BP) has been attracting significant attention to better utilize its inherent properties. The sandwich of zero-dimensional (0D) noble metals within BP-based vdW heterostructures can provide efficient catalytic channels, modulating their surface redox potentials and therefore inducing versatile functionalities. Herein, we realize a 2D WS-Au-BP heterostructure, in which Au nanoparticles are connected between BP and WS via ionic bonds.

Atomic-Scale Deciphering of Multiple Dynamic Phase Transformations and Reversible Sodium Storage in Ternary Metal Sulfide Anode.

Ternary metal sulfides (TMSs), endowed with the synergistic effect of their respective binary counterparts, hold great promise as anode candidates for boosting sodium storage performance. Their fundamental sodium storage mechanisms associated with dynamic structural evolution and reaction kinetics, however, have not been fully comprehended. To enhance the electrochemical performance of TMS anodes in sodium-ion batteries (SIBs), it is of critical importance to gain a better mechanistic understanding of their dynamic electrochemical processes during live (de)sodiation cycling.

Enhancing the ambient stability of few-layer black phosphorus by surface modification.

Based on high-throughput density functional theory calculations, we investigated the adsorption characteristics of various elements across the Periodic Table on few-layer black phosphorus (BP). Using the criterion that the ratio of adsorption energy ( ) to bulk cohesive energy ( ) is greater than one ( / > 1), we selected fifteen elements. The adsorption of these elements on few-layer BPs could significantly shift their conduction-band minimum (CBM) downward, suggesting the possibility of preventing the few-layer BPs from oxidation if the CBM can be shifted below the O/O redox potential.

CO Adsorption on Metal-Decorated Phosphorene.

Using first principle calculations, we have investigated the adsorption of CO gas on various metal-decorated phosphorene. Almost all of the metals were considered to decorate phosphorene. By comparing binding energy ( ) and cohesive energy ( ), only 10 metals (Li, Na, K, Rb, Cs, Ca, Sr, Ba, Pd, and La) can stably decorate phosphorene and avoid clustering.

A 'jump-to-coalescence' mechanism during nanoparticle growth revealed by in situ aberration-corrected transmission electron microscopy observations.

In this work, we used in situ aberration-corrected transmission electron microscopy (AC-TEM) to observe the coalescence of gold nanoparticles. We observed a critical edge-to-edge distance d(c)(e) ~ 0.5 nm below which the two particles will coalesce rapidly (jump-to-coalescence).

Fullerene growth from encapsulated graphene flakes.

The direct in situ observation of fullerene formation encapsulated within a graphene ridge has been made possible using an aberration corrected transmission electron microscope (AC-TEM). An atom-by-atom mechanism was proposed based on in situ AC-TEM observations. First principle calculations found a continuous energy decrease upon the addition of carbon atoms to the edge of the graphene flakes, which mimics the fullerene growth steps and supports the atom-by-atom mechanism.

Orientation Effects in Ballistic High-Strained P-type Si Nanowire FETs.

In order to design and optimize high-sensitivity silicon nanowire-field-effect transistor (SiNW FET) pressure sensors, this paper investigates the effects of channel orientations and the uniaxial stress on the ballistic hole transport properties of a strongly quantized SiNW FET placed near the high stress regions of the pressure sensors. A discrete stress-dependent six-band k.p method is used for subband structure calculation, coupled to a two-dimensional Poisson solver for electrostatics.

Negative index of refraction in metallic metamaterial comprising split-ring resonators.

We numerically investigate the negative index of refraction in a metamaterial composed of metallic split-ring resonators, which exhibits simultaneously negative permittivity and permeability without resorting to additional metallic wires. It is confirmed that, in the left-handed band, negative permittivity is generated in analogy to the cut-wire metamaterial and negative permeability comes from the antisymmetric resonant mode, which occurs at a frequency band about 3 times higher than the fundamental magnetic resonance proposed by Pendry [IEEE Trans. Microwave Theory Tech.