Supramolecular Assembly of Fused Macrocycle-Cage Molecules for Fast Lithium-Ion Transport.

We report a new supramolecular porous crystal assembled from fused macrocycle-cage molecules. The molecule comprises a prismatic cage with three macrocycles radially attached. The molecules form a nanoporous crystal with one-dimensional (1D) nanochannels.

Giant Anisotropic Magnetoresistance in Few-Layer α-RuCl Tunnel Junctions.

The spin-orbit-assisted Mott insulator α-RuCl is proximate to the coveted quantum spin liquid (QSL) predicted by the Kitaev model. In the search for the pure Kitaev QSL, reducing the dimensionality of this frustrated magnet by exfoliation has been proposed as a way to enhance magnetic fluctuations and Kitaev interactions. Here, we perform angle-dependent tunneling magnetoresistance (TMR) measurements on ultrathin α-RuCl crystals with various layer numbers to probe their magnetic, electronic, and crystal structures.

Real-space visualization of a defect-mediated charge density wave transition.

We study the coupled charge density wave (CDW) and insulator-to-metal transitions in the 2D quantum material 1T-TaS. By applying in situ cryogenic 4D scanning transmission electron microscopy with in situ electrical resistance measurements, we directly visualize the CDW transition and establish that the transition is mediated by basal dislocations (stacking solitons). We find that dislocations can both nucleate and pin the transition and locally alter the transition temperature by nearly ~75 K.

Diameter-dependent phase selectivity in 1D-confined tungsten phosphides.

Topological materials confined in 1D can transform computing technologies, such as 1D topological semimetals for nanoscale interconnects and 1D topological superconductors for fault-tolerant quantum computing. As such, understanding crystallization of 1D-confined topological materials is critical. Here, we demonstrate 1D template-assisted nanowire synthesis where we observe diameter-dependent phase selectivity for tungsten phosphides.

Lithiation Induced Phases in 1T'-MoTe Nanoflakes.

Multiple polytypes of MoTe with distinct structures and intriguing electronic properties can be accessed by various physical and chemical approaches. Here, we report electrochemical lithium (Li) intercalation into 1T'-MoTe nanoflakes, leading to the discovery of two previously unreported lithiated phases. Distinguished by their structural differences from the pristine 1T' phase, these distinct phases were characterized using polarization Raman spectroscopy and single-crystal X-ray diffraction.

Nanomolding of Two-Dimensional Materials.

Lateral confinement of layered, two-dimensional (2D) materials has uniquely enabled the exploration of several topological phenomena in electron transport due to the well-defined nanoscale cross-sections and perimeters. At present, research on laterally confined 2D materials is constrained by the lack of synthesis methods that can reliably and controllably produce nanostructures with narrow widths and high aspect ratios. We demonstrate the use of thermomechanical nanomolding (TMNM) to fabricate nanowires of six layered materials (Te, InSe, BiTe, BiSe, GaSe, and SbTe) with widths of 40 nm and aspect ratios above 100.

Scalable Route to Colloidal NiCoS Nanoparticles with Low Dispersity Using Amino Acids.

The thiospinel group of nickel cobalt sulfides (NiCoS) are promising materials for energy applications such as supercapacitors, fuel cells, and solar cells. Solution-processible nanoparticles of NiCoS have advantages of low cost and fabrication of high-performance energy devices due to their high surface-to-volume ratio, which increases the electrochemically active surface area and shortens the ionic diffusion path. The current approaches to synthesize NiCoS nanoparticles are often based on hydrothermal or solvothermal methods that are difficult to scale up safely and efficiently and that preclude monitoring the reaction through aliquots, making optimization of size and dispersity challenging, typically resulting in aggregated nanoparticles with polydisperse sizes.

In operando cryo-STEM of pulse-induced charge density wave switching in TaS.

The charge density wave material 1T-TaS exhibits a pulse-induced insulator-to-metal transition, which shows promise for next-generation electronics such as memristive memory and neuromorphic hardware. However, the rational design of TaS devices is hindered by a poor understanding of the switching mechanism, the pulse-induced phase, and the influence of material defects. Here, we operate a 2-terminal TaS device within a scanning transmission electron microscope at cryogenic temperature, and directly visualize the changing charge density wave structure with nanoscale spatial resolution and down to 300 μs temporal resolution.

Wafer-Scale Fabrication of 2D Nanostructures via Thermomechanical Nanomolding.

With shrinking dimensions in integrated circuits, sensors, and functional devices, there is a pressing need to develop nanofabrication techniques with simultaneous control of morphology, microstructure, and material composition over wafer length scales. Current techniques are largely unable to meet all these conditions, suffering from poor control of morphology and defect structure or requiring extensive optimization or post-processing to achieve desired nanostructures. Recently, thermomechanical nanomolding (TMNM) has been shown to yield single-crystalline, high aspect ratio nanowires of metals, alloys, and intermetallics over wafer-scale distances.

Emergent layer stacking arrangements in c-axis confined MoTe.

The layer stacking order in 2D materials strongly affects functional properties and holds promise for next-generation electronic devices. In bulk, octahedral MoTe possesses two stacking arrangements, the ferroelectric Weyl semimetal T phase and the higher-order topological insulator 1T' phase. However, in thin flakes of MoTe, it is unclear if the layer stacking follows the T, 1T', or an alternative stacking sequence.

Two-Dimensional Violet Phosphorus P: A Large Band Gap Phosphorus Allotrope.

The discovery of novel large band gap two-dimensional (2D) materials with good stability and high carrier mobility will innovate the next generation of electronics and optoelectronics. A new allotrope of 2D violet phosphorus P was synthesized via a salt flux method in the presence of bismuth. Millimeter-sized crystals of violet-P were collected after removing the salt flux with DI water.

Synergizing Electron and Heat Flows in Photocatalyst for Direct Conversion of Captured CO.

We report a ternary hybrid photocatalyst architecture with tailored interfaces that boost the utilization of solar energy for photochemical CO reduction by synergizing electron and heat flows in the photocatalyst. The photocatalyst comprises cobalt phthalocyanine (CoPc) molecules assembled on multiwalled carbon nanotubes (CNTs) that are decorated with nearly monodispersed cadmium sulfide quantum dots (CdS QDs). The CdS QDs absorb visible light and generate electron-hole pairs.

Topological Metal MoP Nanowire for Interconnect.

The increasing resistance of copper (Cu) interconnects for decreasing dimensions is a major challenge in continued downscaling of integrated circuits beyond the 7 nm technology node as it leads to unacceptable signal delays and power consumption in computing. The resistivity of Cu increases due to electron scattering at surfaces and grain boundaries at the nanoscale. Topological semimetals, owing to their topologically protected surface states and suppressed electron backscattering, are promising candidates to potentially replace current Cu interconnects.

Efficient electrocatalytic valorization of chlorinated organic water pollutant to ethylene.

Electrochemistry can provide an efficient and sustainable way to treat environmental waters polluted by chlorinated organic compounds. However, the electrochemical valorization of 1,2-dichloroethane (DCA) is currently challenged by the lack of a catalyst that can selectively convert DCA in aqueous solutions into ethylene. Here we report a catalyst comprising cobalt phthalocyanine molecules assembled on multiwalled carbon nanotubes that can electrochemically decompose aqueous DCA with high current and energy efficiencies.

Axial Higgs mode detected by quantum pathway interference in RTe.

The observation of the Higgs boson solidified the standard model of particle physics. However, explanations of anomalies (for example, dark matter) rely on further symmetry breaking, calling for an undiscovered axial Higgs mode. The Higgs mode was also seen in magnetic, superconducting and charge density wave (CDW) systems.

Compact Super Electron-Donor to Monolayer MoS.

The surface functionalization of two-dimensional (2D) materials with organic electron donors (OEDs) is a powerful tool to modulate the electronic properties of the material. Here we report a novel molecular dopant, Me-OED, that demonstrates record-breaking molecular doping to MoS, achieving a carrier density of 1.10 ± 0.

Unconventional grain growth suppression in oxygen-rich metal oxide nanoribbons.

Nanograined metal oxides are requisite for diverse applications that use large surface area, such as gas sensors and catalysts. However, nanoscale grains are thermodynamically unstable and tend to coarsen at elevated temperatures. Here, we report effective grain growth suppression in metal oxide nanoribbons annealed at high temperature (900°C) by tuning the metal-to-oxygen ratio and confining the nanoribbons.

Synergistic Integration of Chemo-Resistive and SERS Sensing for Label-Free Multiplex Gas Detection.

Practical sensing applications such as real-time safety alerts and clinical diagnoses require sensor devices to differentiate between various target molecules with high sensitivity and selectivity, yet conventional devices such as oxide-based chemo-resistive sensors and metal-based surface-enhanced Raman spectroscopy (SERS) sensors usually do not satisfy such requirements. Here, a label-free, chemo-resistive/SERS multimodal sensor based on a systematically assembled 3D cross-point multifunctional nanoarchitecture (3D-CMA), which has unusually strong enhancements in both "chemo-resistive" and "SERS" sensing characteristics is introduced. 3D-CMA combines several sensing mechanisms and sensing elements via 3D integration of semiconducting SnO nanowire frameworks and dual-functioning Au metallic nanoparticles.

Heterointerface Effects on Lithium-Induced Phase Transitions in Intercalated MoS.

The intercalation-induced phase transition of MoS from the semiconducting 2H to the semimetallic 1T' phase has been studied in detail for nearly a decade; however, the effects of a heterointerface between MoS and other two-dimensional (2D) crystals on the phase transition have largely been overlooked. Here, calculations show that intercalating Li at a MoS-hexagonal boron nitride (BN) interface stabilizes the 1T phase over the 2H phase of MoS by ∼100 mJ m , suggesting that encapsulating MoS with BN may lower the electrochemical energy needed for the intercalation-induced phase transition. However, Raman spectroscopy of BN-MoS-BN heterostructures during the electrochemical intercalation of Li shows that the phase transition occurs at the same applied voltage for the heterostructure as for bare MoS.

cm-Scale Synthesis of MoTe Thin Films with Large Grains and Layer Control.

Owing to the small energy differences between its polymorphs, MoTe can access a full spectrum of electronic states from the 2H semiconducting state to the 1T' semimetallic state and from the T Weyl semimetallic state to the superconducting state in the 1T' and T phase at low temperature. Thus, it is a model system for phase transformation studies as well as quantum phenomena such as the quantum spin Hall effect and topological superconductivity. Careful studies of MoTe and its potential applications require large-area MoTe thin films with high crystallinity and thickness control.

A Highly Efficient All-Solid-State Lithium/Electrolyte Interface Induced by an Energetic Reaction.

The energetic chemical reaction between Zn(NO ) and Li is used to create a solid-state interface between Li metal and Li La Zr Ta O (LLZTO) electrolyte. This interlayer, composed of Zn, ZnLi alloy, Li N, Li O, and other species, possesses strong affinities with both Li metal and LLZTO and affords highly efficient conductive pathways for Li transport through the interface. The unique structure and properties of the interlayer lead to Li metal anodes with longer cycle life, higher efficiency, and better safety compared to the current best Li metal electrodes operating in liquid electrolytes while retaining comparable capacity, rate, and overpotential.