Colloidal Nanoparticles Hold Elementary Charge in Nonpolar Solvent.

The net charge of individual nanoparticles in nonpolar solvents plays a critical role in their intrinsic properties like charge carrier lifetime, electron transport, and interparticle interactions. However, there is a long-standing belief that the oil-dispersed nanoparticles inherently possess no net charge. This work presents an approach for directly quantifying the net charge of individual nanoparticles.

Femtomolar hydrogen sulfide detection via hybrid small-molecule nano-arrays.

Early disease diagnosis hinges on the sensitive detection of signaling molecules. Among these, hydrogen sulfide (HS) has emerged as a critical player in cardiovascular and nervous system signaling. On-chip immunoassays, particularly nanoarray-based interfacial detection, offer promising avenues for ultra-sensitive analysis due to their confined reaction volumes and precise signal localization.

Size-Coded Hydrogel Microbeads for Extraction-Free Serum Multi-miRNAs Quantifications with Machine-Learning-Aided Lung Cancer Subtypes Classification.

Classifying lung cancer subtypes, which are characterized by multi-microRNAs (miRNAs) upregulation, is important for therapy and prognosis evaluation. Liquid biopsy is a promising approach, but the pretreatment of RNA extraction is labor-intensive and impairs accuracy. Here we develop size-coded hydrogel microbeads for extraction-free quantification of miR-21, miR-205, and miR-375 directly from serum.

Probing Single-Particle Electrocatalytic Stability: Electrogenerated Chemiluminescence Imaging of Nanoparticle Array.

Understanding the stability of single nanoparticles is crucial for optimizing their performance in various applications, including catalysis. In this study, we employed electrochemiluminescence (ECL) imaging to investigate the temporal stability of individual Au and Pt nanoparticles within precisely engineered arrays. Our results reveal significant differences in the stability of Au and Pt NPs.

Freeze Metal Halide Perovskite for Dramatic Laser Tuning: Direct Observation via In Situ Cryo-Electron Microscope.

A frozen-temperature (below -28 °C) laser tuning way is developed to optimize metal halide perovskite (MHP)'s stability and opto-electronic properties, for emitter, photovoltaic and detector applications. Here freezing can adjust the competitive laser irradiation effects between damaging and annealing/repairing. And the ligand shells on MHP surface, which are widely present for many MHP materials, can be frozen and act as transparent solid templates for MHP's re-crystallization/re-growth during the laser tuning.

Active Assembly of CsPbBr Nanorods into Microcolumns by Electric Field in Nonpolar Solvent.

High-precision, controllable, mass-producible assembly of nanoparticles into complex structures or devices holds immense importance in the application across various fields but it remains challenging. Here a highly controllable and reversible active assembly of colloidal CsPbBr nanorods, driven by an external electric field is achieved. This approach enables the nanorods dynamically orient themselves, assemble into chains, aggregate into columns, and eventually form an ordered column array, with the electric field intensity varying from 0 to 50 V µm at 100 kHz.

Optically Readable, Physically Unclonable Subwavelength Pixel via Multicolor Quantum Dot Printing for Anticounterfeiting.

We present a secure and user-friendly ultraminiaturized anticounterfeiting labeling technique─the color-encoded physical unclonable nanotag. These nanotags consist of subwavelength spots formed by random combinations of multicolor quantum dots, which are fabricated using a cost-efficient printing method developed in this study. The nanotags support over 170,000 different colors and are inherently resistant to cloning.

Annealed SiO Protective Layer on LiMnO for Enhanced Li-Ion Extraction from Brine.

In this study, we present a novel approach for selective Li-ion extraction from brine using an LiMnO ion sieve coated with a dense silica layer, denoted as LMO@SiO. The SiO layer is controllably coated onto the LMO surface, forming passivation layers and ion permeation filters. This design effectively minimizes the acidic corrosion of the LMO and enhances the Li adsorption capacity.

Photoluminescence Anisotropy in Eutectic Crystals of Polynuclear Lanthanide Complexes and Silver Clusters.

Anisotropy is an intrinsic property of crystalline materials. However, the photoluminescence anisotropy in eutectic crystals of organometallic complexes has remained unexplored. Herein, the eutectic of polynuclear lanthanide complexes and Ag clusters was prepared, and the crystal shows significant photoluminescence anisotropy.

Patterning of Molecules/Ions via Reverse Micelle Vessels by Nanoxerography.

Precise patterning of molecules/ions in the nanometer scale is a crucial but challenging technique for the fabrication of advanced functional nanodevices. We developed a robust method to print molecules/ions into arbitrarily defined patterns with sub-20 nm precision assisted by reverse micelles. The reverse micelle, serving as a nano-sized vessel, can load molecules/ions and then be patterned onto the predefined positions by electrostatic attraction.

Electrostatic-induced green and precise growth of model catalysts.

Crystallographic control of crystals as catalysts with precise geometrical and chemical features is significantly important to develop sustainable chemistry, yet highly challenging. Encouraged by first principles calculations, precise structure control of ionic crystals could be realized by introducing an interfacial electrostatic field. Herein, we report an efficient in situ dipole-sourced electrostatic field modulation strategy using polarized ferroelectret, for crystal facet engineering toward challenging catalysis reactions, which avoids undesired faradic reactions or insufficient field strength by conventional external electric field.

Smart Magnetic Optical Antenna for Automatic Nanoalignment and Photon Beaming from Prepatterned Single Quantum Dot Nanospot.

We present a unidirectional dielectric optical antenna, which can be chemically synthesized and controlled by magnetic fields. By applying magnetic fields, we successfully aligned an optical antenna on a prepatterned quantum dot nanospot with accuracy better than 40 nm. It confined the fluorescence emission into a 16-degree wide beam and enhanced the signal by 11.

Sub-ambient full-color passive radiative cooling under sunlight based on efficient quantum-dot photoluminescence.

Daytime radiative cooling with high solar reflection and mid-infrared emission offers a sustainable way for cooling without energy consumption. However, so far sub-ambient daytime radiative coolers typically possess white/silver color with limited aesthetics and applications. Although various colored radiative cooling designs have been pursued previously, multi-colored daytime radiative cooling to a temperature below ambient has not been realized as the solar thermal effect in the visible range lead to significant thermal load.

Moisture-Dependent Blinking of Individual CsPbBr Nanocrystals Revealed by Single-Particle Spectroscopy.

All-inorganic metal halide perovskite nanocrystals (NCs) have been exceptional candidates for high-performance solution-processed optoelectronic and photonic devices compared with organometal halide perovskite NCs due to their superior stability. However, the interactions between all-inorganic perovskite NCs and moisture, which is an acknowledged detrimental factor, are still under debate, and detailed investigations to uncover such fundamentals remain to be performed. Herein, with wide-field fluorescence microscopy, the burst photoluminescence blinking responses of CsPbBr NCs were observed in ambient air, and moisture rather than oxygen was verified to be the key factor that leads to the enhanced PL intensity and reduced OFF duration.

Plasmon-Enhanced Electrochemiluminescence at the Single-Nanoparticle Level.

Plasmon-enhanced electrochemiluminescence (ECL) at the single-nanoparticle (NP) level was investigated by ECL microscopy. The Au NPs were assembled into an ordered array, providing a high-throughput platform that can easily locate each NP in sequential characterizations. A strong dependence of ECL intensity on Au NP configurations was observed.

Quantized Exciton Motion and Fine Energy-Level Structure of a Single Perovskite Nanowire.

The quantum-confinement effect profoundly influences the exciton energy-level structures and recombination dynamics of semiconductor nanostructures but remains largely unexplored in traditional one-dimensional nanowires mainly due to their poor optical qualities. Here, we show that in defect-tolerant perovskite material of highly luminescent CsPbBr nanowires, the exciton's center-of-mass motion perpendicular to the axial direction is severely confined. This is reflected in the two sets of photoluminescence spectra emitted from a single CsPbBr nanowire, each of which consists of doublet peaks with linear polarizations perpendicular and parallel to the axial direction.

Scalable Production of High-Quality Silver Nanowires via Continuous-Flow Droplet Synthesis.

Silver nanowires (Ag NWs) have shown great potential in next-generation flexible displays, due to their superior electronic, optical, and mechanical properties. However, as with most nanomaterials, a limited production capacity and poor reproduction quality, based on the batch reaction, largely hinder their application. Here, we applied continuous-flow synthesis for the scalable and high-quality production of Ag NWs, and built a pilot-scale line for kilogram-level per day production.

Transferring Liquid Metal to form a Hybrid Solid Electrolyte via a Wettability-Tuning Technology for Lithium-Metal Anodes.

Integrating solid-state electrolyte (SSE) into Li-metal anodes has demonstrated great promise to unleash the high energy density of rechargeable Li-metal batteries. However, fabricating a highly cyclable SSE/Li-metal anode remains a major challenge because the densification of the SSE is usually incompatible with the reactive Li metal. Here, a liquid-metal-derived hybrid solid electrolyte (HSE) is proposed, and a facile transfer technology to construct an artificial HSE on the Li metal is reported.

Modulating the Chemical Microenvironment of Pt Nanoparticles within Ultrathin Nanosheets of Isoreticular MOFs for Enhanced Catalytic Activity.

The catalytic activity of metal nanoparticles (MNPs) embedded in metal-organic frameworks (MOFs) is affected by the electronic interactions between MNPs and MOFs. In this report, we fabricate a series of ultrathin nanosheets of isoreticular MOFs (NMOFs) with different metal nodes as supports and successfully encapsulate Pt NPs within these NMOFs, affording , , , and nanocomposites. The microchemical environment on the surface of Pt NPs can be modulated by varying the metal nodes of NMOFs.

Engineering Two-Dimensional Metal-Organic Framework on Molecular Basis for Fast Li Conduction.

Metal-organic frameworks (MOFs) have been proposed as emerging fillers for composite polymer electrolytes (CPEs). However, MOF particles are usually served as passive fillers that yield limited ionic conductivity improvement. Building continuous MOF reinforcements and exploiting their active roles remain challenging.

Ultrasonic activation of inert poly(tetrafluoroethylene) enables piezocatalytic generation of reactive oxygen species.

Controlled generation of reactive oxygen species (ROS) is essential in biological, chemical, and environmental fields, and piezoelectric catalysis is an emerging method to generate ROS, especially in sonodynamic therapy due to its high tissue penetrability, directed orientation, and ability to trigger in situ ROS generation. However, due to the low piezoelectric coefficient, and environmental safety and chemical stability concerns of current piezoelectric ROS catalysts, novel piezoelectric materials are urgently needed. Here, we demonstrate a method to induce polarization of inert poly(tetrafluoroethylene) (PTFE) particles ( ~ 1-5 μm) into piezoelectric electrets with a mild and convenient ultrasound process.

The Role of Polymer and Inorganic Coatings to Enhance Interparticle Connections Diagnosed by Techniques.

Surface coating on alloy anodes renders an effective remedy to tolerate internal stress and alleviate the side reaction with electrolytes for long-lasting reversible lithium redox reactions in lithium-ion batteries. However, the role of surface coating on the interparticle connections of alloy anodes remains not fully understood. Herein, we exploit real-time lithiation and mechanic measurement of SnO nanoparticles via TEM with different coating layers, including conducting polymer polypyrrole and metal oxide MnO.

Unexpected Coulomb Interactions in Nonpolar Solvent for Highly Efficient Nanoxerography of Perovskite Quantum Dots.

In this work, an unexpected sign-dependent electrostatic assembly, also known as nanoxerography, of perovskite quantum dots was observed in nonpolar solutions. Electrical force microscope measurements showed that CsPbBr quantum dots carry negative charges and tend to aggregate at the positively charged nanospots via Coulomb interactions despite that they are synthesized and dispersed in a neutral nonpolar solvent. The result was further confirmed by a statistical method developed in this work based on the Gibbs-Boltzmann distribution.

High-resolution combinatorial patterning of functional nanoparticles.

Fast, low-cost, reliable, and multi-component nanopatterning techniques for functional colloidal nanoparticles have been dreamed about by scientists and engineers for decades. Although countless efforts have been made, it is still a daunting challenge to organize different nanocomponents into a predefined structure with nanometer precision over the millimeter and even larger scale. To meet the challenge, we report a nanoprinting technique that can print various functional colloidal nanoparticles into arbitrarily defined patterns with a 200 nm (or smaller) pitch (>125,000 DPI), 30 nm (or larger) pixel size/linewidth, 10 nm position accuracy and 50 nm overlay precision.

Deterministic Assembly of Single Sub-20 nm Functional Nanoparticles Using a Thermally Modified Template with a Scanning Nanoprobe.

A deterministic assembly technique for single sub-20 nm functional nanoparticles is developed based on nanostructured templates fabricated by hot scanning nanoprobes. With this technique, single nanoparticles including quantum dots, polystyrene fluorescent nanobeads, and gold nanoparticles are successfully assembled into 2D arrays with high yields. Experimental and theoretical analyses show that the key for the high yields is the hot-probe-based template fabrication technique, which creates geometrical nanotraps and modifies their surface energy simultaneously.