Piezoelectricity in wide bandgap semiconductor 2D crystal GaN nanosheets.

Gallium nitride (GaN) exhibits various potential applications in optics and optoelectronics due to its outstanding physical characteristics, including a wide direct bandgap, strong deep-ultraviolet emission, and excellent electron transport properties. However, research on the piezoelectric and related properties of GaN nanosheets are scarce, as previous small-scale GaN investigations have mainly concentrated on nanowires and nanotubes. Here, we report a strategy for growing 2D GaN nanosheets using chemical vapor deposition on Ga/W liquid-phase substrates.

Above-Room-Temperature Strong Ferromagnetism in 2D MnB Nanosheet.

Two-dimensional (2D) room-temperature (RT) ferromagnetic materials have amassed considerable interest in the field of fundamental physics for applications in next-generation spintronic devices owing to their physical properties. However, realizing strong RT ferromagnetism and a high Curie temperature () in these 2D magnetic materials remains challenging. Herein, we develop a 2D MnB nanosheet for known 2D ferromagnets that demonstrates strong RT ferromagnetism and a record-high above-RT of ∼585.

Extending on-surface synthesis from 2D to 3D by cycloaddition with C.

As an efficient molecular engineering approach, on-surface synthesis (OSS) defines a special opportunity to investigate intermolecular coupling at the sub-molecular level and has delivered many appealing polymers. So far, all OSS is based on the lateral covalent bonding of molecular precursors within a single molecular layer; extending OSS from two to three dimensions is yet to be realized. Herein, we address this challenge by cycloaddition between C and an aromatic compound.

Photocatalytic nanocomposite membranes for environmental remediation.

We report the design and one-pot synthesis of Ag-doped BiVOembedded in reduced graphene oxide (BiVO:Ag/rGO) nanocomposites via a hydrothermal processing route. The binary heterojunction photocatalysts exhibited high efficiency for visible light degradation of model dyes and were correspondingly used for the preparation of photocatalytic membranes using polyvinylidene fluoride (PVDF) or polyethylene glycol (PEG)-modified polyimide (PI), respectively. The surface and cross-section images combined with elemental mapping illustrated the effective distribution of the nanocomposites within the polymeric membranes.

Cu S Capped AuCu Nanostars for Efficient Plasmonic Photothermal Tumor Treatment in the Second Near-Infrared Window.

Plasmonic nanohybrids are promising photo energy conversion materials in photoelectronics and biomedicine, due to their unique surface plasmon resonance (SPR). Au and Cu S nanostructures with strong SPR in the near-infrared (NIR) spectral region are classic plasmonic systems used to convert NIR photons into heat for photothermal therapy (PTT). The rational design of the Au/Cu S nanohybrids is expected to induce better photothermal conversion; however, the construction of such hybrids via wet-chemistry methods with a well-controlled interfacial structure is still challenging.

On-Surface Decarboxylation Coupling Facilitated by Lock-to-Unlock Variation of Molecules upon the Reaction.

On-surface synthesis (OSS) involving relatively high energy barriers remains challenging due to a typical dilemma: firm molecular anchor is required to prevent molecular desorption upon the reaction, whereas sufficient lateral mobility is crucial for subsequent coupling and assembly. By locking the molecular precursors on the substrate then unlocking them during the reaction, we present a strategy to address this challenge. High-yield synthesis based on well-defined decarboxylation, intermediate transition, and hexamerization is demonstrated, resulting in an extended and ordered network exclusively composed of the newly synthesized macrocyclic compound.

Mesenchymal Stem Cell-Laden Hydrogel Microfibers for Promoting Nerve Fiber Regeneration in Long-Distance Spinal Cord Transection Injury.

Mesenchymal stem cell (MSC)-based regenerative medicine is widely considered as a promising approach for repairing tissue and re-establishing function in spinal cord injury (SCI). However, low survival rate, uncontrollable migration, and differentiation of stem cells after implantation represent major challenges toward the clinical deployment of this approach. In this study, we fabricated three-dimensional MSC-laden microfibers via electrospinning in a rotating cell culture to mimic nerve tissue, control stem cell behavior, and promote integration with the host tissue.

Long-range ordered and atomic-scale control of graphene hybridization by photocycloaddition.

Chemical reactions that convert sp to sp hybridization have been demonstrated to be a fascinating yet challenging route to functionalize graphene. So far it has not been possible to precisely control the reaction sites nor their lateral order at the atomic/molecular scale. The application prospects have been limited for reactions that require long soaking, heating, electric pulses or probe-tip press.

Direct Measurement of Electronic Band Structure in Single Quantum Dots of Metal Chalcogenide Composites.

Metal chalcogenide quantum dots (QDs) are among the most promising materials as light harvesters in all-inorganic systems for applications in solar cells and production of solar fuels. The electronic band structure of composite QDs formed by lead and cadmium chalcogenides directly grafted on highly oriented pyrolytic graphite surfaces through successive ionic layer absorption and reaction is investigated. Atomic force microscopy and Kelvin probe force microscopy (KPFM) are applied to investigate PbS, CdS, and PbS/CdS QD systems.

Supramolecular Assemblies on Surfaces: Nanopatterning, Functionality, and Reactivity.

Understanding how molecules interact to form large-scale hierarchical structures on surfaces holds promise for building designer nanoscale constructs with defined chemical and physical properties. Here, we describe early advances in this field and highlight upcoming opportunities and challenges. Both direct intermolecular interactions and those that are mediated by coordinated metal centers or substrates are discussed.

Enhanced conversion efficiency in Si solar cells employing photoluminescent down-shifting CdSe/CdS core/shell quantum dots.

Silicon solar cells have captured a large portion of the total market of photovoltaic devices mostly due to their relatively high efficiency. However, Silicon exhibits limitations in ultraviolet absorption because high-energy photons are absorbed at the surface of the solar cell, in the heavily doped region, and the photo-generated electron-hole pairs need to diffuse into the junction region, resulting in significant carrier recombination. One of the alternatives to improve the absorption range involves the use of down-shifting nano-structures able to interact with the aforementioned high energy photons.

Combined magnetron sputtering and pulsed laser deposition of TiO and BFCO thin films.

We report the successful demonstration of a hybrid system that combines pulsed laser deposition (PLD) and magnetron sputtering (MS) to deposit high quality thin films. The PLD and MS simultaneously use the same target, leading to an enhanced deposition rate. The performance of this technique is demonstrated through the deposition of titanium dioxide and bismuth-based perovskite oxide BiFeCrO (BFCO) thin films on Si(100) and LaAlO (LAO) (100).

Modulating Exciton Dynamics in Composite Nanocrystals for Excitonic Solar Cells.

Quantum dots (QDs) represent one of the most promising materials for third-generation solar cells due to their potential to boost the photoconversion efficiency beyond the Shockley-Queisser limit. Composite nanocrystals can challenge the current scenario by combining broad spectral response and tailored energy levels to favor charge extraction and reduce energy and charge recombination. We synthesized PbS/CdS QDs with different compositions at the surface of TiO2 nanoparticles assembled in a mesoporous film.