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Layered 2D (PbI₂)_1−x(BiI₃)_xmaterials exhibit a nonlinear dependence in structural and charge transport properties unanticipated from the combination of PbI₂and BiI₃. Within (PbI₂)_1−x(BiI₃)_xcrystals, phase integration yields deceptive structural features, while phase boundary separation leads to new conductance switching behavior observed as large peaks in current during current–voltage (I–V) measurements (±100 V). Temperature‐ and time‐dependent electrical measurements demonstrate that the behavior is attributed to ionic transport perpendicular to the layers. High‐resolution transmission electron microscopy reveals that the structure of (PbI₂)_1−x(BiI₃)_xis a “brick wall” consisting of two phases, Pb‐rich and Bi‐rich. These brick‐like features are 10s nm a side and it is posited that iodide ion transport at the interfaces of these regions is responsible for the conductance switching action.

 

The practical application of lithium (Li) metal anode (LMA) is still hindered by non‐uniformity of solid electrolyte interphase (SEI), formation of “dead” Li, and continuous consumption of electrolyte although LMA has an ultrahigh theoretical specific capacity and a very low electrochemical redox potential. Herein, a facile protection strategy is reported for LMA using a double layer (DL) coating that consists of a polyethylene oxide (PEO)‐based bottom layer that is highly stable with LMA and promotes uniform ion flux, and a cross‐linked polymer‐based top layer that prevents solvation of PEO layer in electrolytes. Li deposited on DL‐coated Li (DL@Li) exhibits a smoother surface and much larger size than that deposited on bare Li. The LiF/Li₂O enriched SEI layer generated by the salt decomposition on top of DL@Li further suppresses the side reactions between Li and electrolyte. Driven by the abovementioned advantageous features, the DL@Li||LiNi_0.6Mn_0.2Co_0.2O₂cells demonstrate capacity retention of 92.4% after 220 cycles at a current density of 2.1 mA cm^–2(C/2 rate) and stability at a high charging current density of 6.9 mA cm^–2(1.5 C rate). These results indicate that the DL protection is promising to overcome the rate limitation of LMAs and high energy‐density Li metal batteries.

 

β-Ga2O3 is emerging as an interesting wide band gap semiconductor for solar blind photo detectors (SBPD) and high power field effect transistors (FET) because of its outstanding material properties including an extremely wide bandgap (Eg ~4.9eV) and a high breakdown field (8 MV/cm). This review summarizes recent trends and progress in the growth/doping of β-Ga2O3 thin films and then offers an overview of the state-of-the-art in SBPD and FET devices. The present challenges for β-Ga2O3 devices to penetrate the market in real-world applications are also considered, along with paths for future work. 

Corrosion is a significant problem for the stability of structural metals and potentially for functional nanomaterials in operating environments. When two metals with different electrochemical potentials form a junction, galvanic corrosion occurs, resulting in the sacrificial dissolution of the metal with a higher oxidation potential (lower electrode potential). Here, it is shown that bimetallic hetero‐nanostructures composed of phase‐segregated metals undergo galvanic corrosion in aqueous environments. Such selective etching of the sacrificial metal in heterojunction particles leads to the formation of unusual and kinetically stabilized half‐spheroid particles. By using a fluid cell and in situ scanning transmission electron microscopy, a two‐stage corrosion process can be observed where the Cu experiences a fractal breakdown before the Ag corrodes due to the lack of a protective oxide layer. However, when treated with a mild Ar plasma, the stability of these structures against corrosion is enhanced due to the conversion of the amorphous native oxide to a denser, thin layer of CuO on the Cu surface. Taken together, this work highlights the importance of considering the effects of galvanic corrosion on the stability of multicomponent nanoparticles, and it shows how mass transport in a nanoscale system is influenced by redox processes.

 

High-energy nickel (Ni)–rich cathode will play a key role in advanced lithium (Li)–ion batteries, but it suffers from moisture sensitivity, side reactions, and gas generation. Single-crystalline Ni-rich cathode has a great potential to address the challenges present in its polycrystalline counterpart by reducing phase boundaries and materials surfaces. However, synthesis of high-performance single-crystalline Ni-rich cathode is very challenging, notwithstanding a fundamental linkage between overpotential, microstructure, and electrochemical behaviors in single-crystalline Ni-rich cathodes. We observe reversible planar gliding and microcracking along the (003) plane in a single-crystalline Ni-rich cathode. The reversible formation of microstructure defects is correlated with the localized stresses induced by a concentration gradient of Li atoms in the lattice, providing clues to mitigate particle fracture from synthesis modifications.

 

Lateral heterogeneities in atomically thin 2D materials such as in‐plane heterojunctions and grain boundaries (GBs) provide an extrinsic knob for manipulating the properties of nano‐ and optoelectronic devices and harvesting novel functionalities. However, these heterogeneities have the potential to adversely affect the performance and reliability of the 2D devices through the formation of nanoscopic hot‐spots. In this report, scanning thermal microscopy (SThM) is utilized to map the spatial distribution of the temperature rise within monolayer transition metal dichalcogenide (TMD) devices upon dissipating a high electrical power through a lateral interface. The results directly demonstrate that lateral heterojunctions between MoS₂and WS₂do not largely impact the distribution of heat dissipation, while GBs of MoS₂appreciably localize heating in the device. High‐resolution scanning transmission electron microscopy reveals that the atomic structure is nearly flawless around heterojunctions but can be quite defective near GBs. The results suggest that the interfacial atomic structure plays a crucial role in enabling uniform charge transport without inducing localized heating. Establishing such structure–property‐processing correlation provides a better understanding of lateral heterogeneities in 2D TMD systems which is crucial in the design of future all‐2D electronic circuitry with enhanced functionalities, lifetime, and performance.