Nitride Nanocrystals Research Articles

Room temperature reversible Ca-metal chemistry in commercial fluorinated calcium salt ester electrolytes enabled by a compact N-rich interphase layer

Multivalent metal batteries serve as crucial complements to lithium-ion batteries. Nevertheless, fluorinated anions designed for energy storage at high voltages readily passivate the metal anodes in common ester electrolytes, particularly for Ca-metal batteries (CMBs). Ca plating/stripping can hardly occur continuously in common fluorinated calcium salt ester electrolytes due to severe corrosion at room temperature. To address the challenging issue, a uniform artificial interface of calcium fluoride nitride nanocrystals (Ca2NF) and amorphous organic species is engineered in the top of Ca-metal electrodes. The compact inorganic/organic hybrid solid electrolyte interphase (SEI) layer avoided the direct reaction of Ca-metal and corrosive fluorinated anions, effectively preventing the continuous passivation of Ca-metal and expediting the diffusion kinetics of calcium ions at the interface. Therefore, for the first time, stable Ca plating/stripping at 0.005 mA cm−2 over 420 h in a commercial fluorinated calcium salt ester electrolyte is achieved for the Ca-metal electrode with the protective SEI, far superior to that of mere hours for the pristine Ca-metal. The enhanced reversibility is also substantiated in Ca-metal full batteries with biomass-derived carbon cathode, delivering stable cycling performance. This work underscores the importance of interface and interphase engineering as an effective avenue for advancing the development of CMBs.

Quantum Physical Unclonable Function Based on Multidimensional Fingerprint Features of Single Photon Emitters in Random AlN Nanocrystals

AbstractPhysical unclonable function (PUF) has emerged as a unique physical'fingerprint' that is inherently difficult to replicate. It shows tremendous application value in various hardware security areas such as identity authentication, chip anticounterfeiting, communication encryption, blockchain, etc. However, with the rapid development of 3D nanoprinting, classical PUFs constructed with disordered micro‐nanostructures face tremendous threats from physical cloning attacks. Herein, this study proposes and demonstrates the utilization of room‐temperature single‐photon emitters derived from atomic defects in randomly distributed pyramidal aluminum nitride (AlN) nanocrystals as a novel quantum PUF to resist physical cloning attacks. The fabrication of this quantum PUF on silicon (Si) wafers enables seamless integration with silicon photonic integrated circuits. The multidimensional fingerprint features of the single‐photon emitters are highly sensitive to the lattice parameters of the uneven AlN nanocrystals. Furthermore, each single photon emitter can work as a quantum random number generator to ensure the fundamental unpredictability of PUFs. The subatomic precision requirement coupled with unpredictable quantum emission behavior makes it practically impossible to attack the proposed quantum PUF, providing a promising solution for information security in the post‐quantum era.

High-Entropy Metal Nitride Embedded in Concave Porous Carbon Enabling Polysulfide Conversion in Lithium-Sulfur Batteries.

The practical implementation of lithium-sulfur batteries is severely hindered by the rapid capacity fading due to the solubility of the intermediate lithium polysulfides (LiPSs) and the sluggish redox kinetics. Herein, high-entropy metal nitride nanocrystals (HEMN) embedded within nitrogen-doped concave porous carbon (N-CPC) polyhedra are rationally designed as a sulfur host via a facile zeolitic imidazolate framework (ZIF)-driven adsorption-nitridation process toward this challenge. The configuration of high-entropy with incorporated metal manganese (Mn) and chromium (Cr)will optimize the d-band center of active sites with more electrons occupied in antibonding orbitals, thus promoting the adsorption and catalytic conversion of LiPSs. While the concave porous carbon not only accommodates the volume change upon the cycling processes but also physically confines and exposes active sites for accelerated sulfur redox reactions. As a result, the resultant HEMN/N-CPC composites-based sulfur cathode can deliver a high specific capacity of 1274 mAh g-1 at 0.2C and a low capacity decay rate of 0.044% after 1000 cycles at 1C. Moreover, upon sulfur loading of 5.0mg cm-2, the areal capacity of 5.0mAhcm-2 can still be achieved. The present work may provide a new avenue for the design of high-performance cathodes in Li-S batteries.

Defect formation analysis in gamma-irradiated titanium nitride nanocrystals: predictions from positron annihilation studies

Defect formation analysis in gamma-irradiated titanium nitride nanocrystals: predictions from positron annihilation studies

Heavily Doped Carbon Nitride Nanocrystal Promotes Visible-Near-Infrared Photosynthesis of Hydrogen Peroxide with Near-Unit Photon Utilization.

Direct photosynthesis of hydrogen peroxide (H2O2) from water and oxygen represents an intriguing alternative to the current indirect process involving the reduction and oxidation of quinones. However, limited light utilization and sluggish charge transfer largely impede overall photocatalytic efficiency. Herein, we present a heavily doped carbon nitride (CNKLi) nanocrystal for efficient and selective photoproduction of H2O2 via a two-electron oxygen reduction reaction (ORR) pathway. CNKLi induces metal-to-ligand charge transfer (MLCT) and electron trapping, which broadens the light absorption to the visible-near-infrared (vis-NIR) spectrum and prolongs the photoelectron lifetime to the microsecond time scale with an exceptional charge diffusion length of ∼1200 nm. Near-unit photoutilization with an apparent quantum yield (AQY) of 100% for H2O2 generation is achieved below 420 nm. Impressively, CNKLi exhibits an appreciable AQY of 16% at 700 nm, which reaches the absorption capacity (∼16%), thus suggesting a near-unit photon utilization <700 nm. In situ characterization and theoretical calculations reveal the facilitated charge transfer from K+ to the heptazine ring skeleton. These findings provide an approach to improve the photosynthetic efficiency of direct H2O2 preparation in the vis-NIR region and expand applications for driving kinetically slow and technologically desirable oxidations or high-value chemical generation.

КОМПОЗИТНЫЕ МАТЕРИАЛЫ НА ОСНОВЕ ПОЛИМЕР/ГРАФЕНА В РОБОТИЗИРОВАННЫХ УСТАНОВКАХ ПОЖАРОТУШЕНИЯ

It is shown that numerous devices contain their own electrical power sources that use a significant number of bipolar transistors and thyristors of medium and high power, which require additional cooling in the form of external radiators to remove excess heat. For their manufacture, in addition to traditional alloys based on aluminum, materials such as polymers with fillers of high thermal conductivity are promising. A composite surface saturation technology is proposed that uses boron nitride nanocrystals to reduce thermal resistance at the interface. It has been established that the heat-conducting properties both along and across the polymer fibers, as the content of the nanocrystalline form of boron nitride increases to 25 %, they increase and reach a value of 21,3 W/(m K). This value is more than twice the possible maximum thermal conductivity coefficient in the absence of a graphene layer: 9,8 W/(m K) with a boron nitride mass content of up to 50 %. Due to its characteristics, polymer/graphene composite material has promise as a material for cooling devices with high energy density.

Cation Exchange in Colloidal Transition Metal Nitride Nanocrystals.

Transition metal nitride (TMN)-based nanostructures have emerged as promising materials for diverse applications in electronics, photonics, energy storage, and catalysis due to their highly desirable physicochemical properties. However, synthesizing TMN-based nanostructures with designed compositions and morphologies poses challenges, especially in the solution phase. The cation exchange reaction (CER) stands out as a versatile postsynthetic strategy for preparing nanostructures that are otherwise inaccessible through direct synthesis. Nevertheless, exploration of the CER in TMNs lags behind that in metal chalcogenides and metal phosphides. Here, we demonstrate cation exchange in colloidal metal nitride nanocrystals, employing Cu3N nanocrystals as starting materials to synthesize Ni4N and CoN nanocrystals. By controlling the reaction conditions, Cu3N@Ni4N and Cu3N@CoN core@shell heterostructures with tunable compositions can also be obtained. The Ni4N and CoN nanocrystals are evaluated as catalysts for the electrochemical oxygen evolution reaction (OER). Remarkably, CoN nanocrystals demonstrate superior OER performance with a low overpotential of 286 mV at 10 mA·cm-2, a small Tafel slope of 89 mV·dec-1, and long-term stability. Our CER approach in colloidal TMNs offers a new strategy for preparing other metal nitride nanocrystals and their heterostructures, paving the way for prospective applications.

Boron nitride nanosheet @ quantum‐sized diamond nanocrystal complex/epoxy nanocomposites with enhancing thermal conductivity and sufficient dielectric breakdown strength

AbstractWith the development of high‐voltage and high‐power devices in the direction of compactness, lightness and extreme working environments, the contradiction between thermal conductivity and dielectric breakdown strength is becoming more and more obvious. In this work, a novel boron nitride nanosheet with uniformly dispersed diamond nanocrystalline (abbreviated as BA@DN) was prepared via facile acidizing hydroxylation, in situ copolymerization self‐assembly of dopamine and blending process. The obtained hybrid filler was employed to embed into epoxy matrix, showing enhanced thermal conductivity and sufficient dielectric breakdown strength. For example, the through‐plane and in‐plane thermal conductivity of epoxy composite with 5% BA@DN‐2 reaches to 0.56 and 3.824 W/m K, respectively. The study proposes a modified plane thermal conductivity model. Based on calculations, it was found that the modified thermal conductivity of 5% BA@DN‐2 is 3.47 W/m K, which is significantly higher than that of pure EP, specifically 17.35 times higher. These findings are significant in terms of materials science. while its alternating current and direct current dielectric breakdown strength are 48.84 and 136.31 kV/mm, about 85.68% and 99.1% of pure epoxy, respectively. The mechanism of outstanding dielectric breakdown strength was analyzed via dielectric characteristic, partial discharge performance and the theory of quantum size effect. In addition, a modified multi‐core model with a multilevel overlapping interface is presented.Highlights The acidified diamond nanocrystals (DNs) were attached to dopamine‐coated boron nitride nanocrystals by a blending process. The small size effect of DNs allows the epoxy film to have both high thermal conductivity and high insulation properties. A thermal conductivity correction model is proposed to eliminate the effect of graphite layer on the film.

Synthesis of Size-Tunable Indium Nitride Nanocrystals

Indium nitride (InN) is an air stable III-V semiconductor with a small band gap of 0.7 eV and as such is of interest as a key material in near-infrared (NIR) LEDs, photodetectors, and multijunction solar cells. Conventionally, InN has been synthesized through physical deposition techniques which involve extreme temperatures and harsh conditions and yield nonluminescent materials. Here we report a new low temperature, solution-based synthetic route to colloidal InN nanocrystals that produces phase-pure wurtzite InN with tunable photoluminescence. The luminescence is attributed to the presence of InN surface states.

Vanadium nitride nanocrystals decorated ultrathin, N-rich and hierarchically porous carbon nanosheets as superior polysulfides mediator for stable lithium-sulfur batteries

The diligent exploitation of high-efficiency polysulfides mediators have exhibited enormous prospects to promote the cycling performance of lithium-sulfur (Li–S) batteries with desirable sulfur loading and high sulfur utilization efficiency. Herein, we craft an elaborated catalyst of ultrafine vanadium nitride nanocrystals confined hierarchically porous, ultrathin nitrogen-doped carbon nanosheets (denoted as VN@NC) via a simple approach. Owing to the highly conductive porous carbon framework integrated with enriched V–N–C active sites, well-heterostructured VN@NC can actively favor the entrapping–adsorption–catalytic conversion of the polysulfides intermediates for boosted surface redox kinetics. As the separator interlayer, VN@NC dedicates to high-performance Li–S batteries with high discharge capacities (1594.8 mAh g−1 at 0.1 C), excellent rate capabilities (766.5 mAh g−1 at 5.0 C) and exceptional cyclic durability by a slight decay of 0.067% per cycle upon 500 cycles at 1.0 C. Interestingly, two cycled Li–S batteries after 100 cycles at 0.5 C can be connected to charge a daily smartphone. Even under elevated sulfur loading of 4.5 mg cm−2 and lean electrolyte of 8 μL mg−1, the assembled Li–S battery still maintains a stable cycling performance. The cost-effective VN@NC catalyst could offer a viable avenue to construct applicable sulfur catalysts for advanced Li–S batteries.

Supramolecular confinement synthesis of ultrafine iron nitride nanocrystals for the oxygen reduction reaction in Zn–air batteries

Ultrafine Fe3N nanocrystals (less than 1.5 nm) embedded in nitrogen-doped carbon are synthesized via a supramolecular confinement strategy for the efficient electrocatalytic ORR in Zn–air batteries.

Low-Divergence hBN Single-Photon Source with a 3D-Printed Low-Fluorescence Elliptical Polymer Microlens.

Efficiently collecting light from single-photon emitters is crucial for photonic quantum technologies. Here, we develop and use an ultralow fluorescence photopolymer to three-dimensionally print micrometer-sized elliptical lenses on individual precharacterized single-photon emitters in hexagonal boron nitride (hBN) nanocrystals, operating in the visible regime. The elliptical lens design beams the light highly efficiently into the far field, rendering bulky objective lenses obsolete. Using back focal plane imaging, we confirm that the emission is collimated to a narrow low-divergence beam with a half width at half-maximum of 2.2°. Using photon correlation measurements, we demonstrate that the single-photon character remains undisturbed by the polymer lens. The strongly directed emission and increased collection efficiency is highly beneficial for quantum optical experiments. Furthermore, our approach paves the way for a highly parallel fiber-based detection of single photons from hBN nanocrystals.

Self-Modifying Nanointerface Driving Ultrahigh Bidirectional Thermal Conductivity Boron Nitride-Based Composite Flexible Films

HighlightsThe flexible composite film presents ultrahigh thermal conductivity and good thermal management performance in electronic devices.An original “self-modified nanointerface” strategy is used to reduce the interfacial thermal resistance between boron nitride and the polymer matrix.The ideal phonon spectrum matching between boron nitride nanocrystals and fillers as well as the strong interaction between self-modified fillers and the polymer matrix are the two major contributors to decrease the interfacial thermal resistance.

Cobalt nitride nanocrystals coated separator as multifunctional interlayer for improving polysulfides regulation

Using transition metal oxides to inhibit the shuttle effect of soluble polysulfides is one of the effective ways to improve the cycling capacity of Li–S batteries. However, due to their unsatisfactory electrical conductivity, the redox reactions of polysulfides adsorbed on transition metal oxide surface cannot occur in time and completely, thus increasing the electrode polarization. Herein, highly conductive Co4N nanocrystals were prepared and successfully used for separator modification of sulfur cathode. As an efficient intermediate layer, Co4N-Celgard not only effectively inhibited the diffusion and shuttle of polysulfides, but also promoted the corresponding conversion reactions due to its high catalytic activity and electrical conductivity, avoiding the ineffective accumulation of lithium polysulfides. Meanwhile, Co4N nanocrystals had good electrolyte affinity, which could effectively improve electrode dynamics. Based on the above advantages, Li–S cell with Co4N-Celgard separator exhibited high rate performance of 626 mA h g−1 at 4 C and low decay rate of 0.089 % per cycle.

Synergistic effect of hybrid hydroxylated boron nitride and cellulose nanocrystals for enhancing the thermal, mechanical, and hydrophobic properties of composite film

AbstractHybrid composite films are largely preferred over neat films because of their superior thermal, mechanical, chemical, and hydrophobic properties. The hybrid composite film has a wide range of use, including space, defense, electronics, packaging, and engineering applications. Fabricating multifunctional hybrid composite films with biodegradable polymer and biodegradable filler such as cellulose nanocrystals has become popular in recent years as an alternative to conventional plastics. In this paper, hybrid hydroxylated boron nitride (BN) nanoparticles with CNC nano‐filer reinforced composite PVA films were fabricated. The obtained composite films were characterized for morphological, chemical, physical, thermal, and hydrophobic properties. The morphological analysis indicates that the hybrid nano‐filler was well dispersed in the poly(vinyl alcohol) (PVA) matrix. The reaction and hydrogen bond interactions between CNC and BN in composite films are confirmed by the Fourier transform infrared spectroscopy and x‐ray diffraction pattern. The contact angle method is used to confirm the enhancement of the hydrophobic property. The physical properties of the composite films and neat PVA film were analyzed by tensile test method using a universal testing machine. The thermal stability of the neat PVA film and the composite films were analyzed by the thermo‐gravimetric analysis method. The effect of hybridization of nanoparticles on the thermal, mechanical, and hydrophobic properties was studied. The hybrid composite film with enhanced properties allows it for multifunctional applications.

In Situ Surface Restraint-Induced Synthesis of Transition-Metal Nitride Ultrathin Nanocrystals as Ultrasensitive SERS Substrate with Ultrahigh Durability.

It is a major challenge to synthesize crystalline transition-metal nitride (TMN) ultrathin nanocrystals due to their harsh reaction conditions. Herein, we report that highly crystalline tungsten nitride (W2N, WN, W3N4, W2N3) nanocrystals with small size and excellent dispersibility are prepared by a mild and general in situ surface restraint-induced growth method. These ultrafine tungsten nitride nanocrystals are immobilized in ultrathin carbon layers, forming an interesting hybrid nanobelt structure. The hybrid WN/C nanobelts exhibit a strong localized surface plasmon resonance (LSPR) effect and surface-enhanced Raman scattering (SERS) effect, including a lowest detection limit of 1 × 10-12 M and a Raman enhancement factor of 6.5 × 108 comparable to noble metals, which may be one of the best records for non-noble metal SERS substrates. Moreover, they even can maintain the SERS performance in a variety of harsh environments, showing outstanding corrosion resistance, radiation resistance, and oxidation resistance, which is not available on traditional noble metal and semiconductor SERS substrates. A synergistic Raman enhancement mechanism of LSPR and interface charge transfer is found in the carbon-coated tungsten nitride substrate. A microfluidic SERS channel integrating the enrichment and detection of trace substances is constructed with the WN/C nanobelt, which realizes high-throughput dynamic SERS analysis.

Phase-Controlled Synthesis of Nickel-Iron Nitride Nanocrystals Armored with Amorphous N-Doped Carbon Nanoparticles Nanocubes for Enhanced Overall Water Splitting.

Transition metal nitrides (TMNs) nanostructures possess distinctive electronic, optical, and catalytic properties, showing great promise to apply in clean energy, optoelectronics, and catalysis fields. Nonetheless, phase-regulation of NiFe-bimetallic nitrides nanocrystals or nanohybrid architectures confronts challenges and their electrocatalytic overall water splitting (OWS) performances are underexplored. Herein, novel pure-phase Ni2+ x Fe2- x N nanocrystals armored with amorphous N-doped carbon (NC) nanoparticles nanocubes (NPNCs) are obtained by controllable nitridation of NiFe-Prussian-blue analogues derived oxides/NC NPNCs under Ar/NH3 atmosphere. Such Ni2+ x Fe2- x N/NC NPNCs possess mesoporous structures and show enhanced electrocatalytic activity in 1m KOH electrolyte with the overpotential of 101 and 270mV to attain 10 and 50mAcm-2 current toward hydrogen and oxygen evolution reactions, outperforming their counterparts (mixed-phase NiFe2 O4 /Ni3 FeN/NC and NiFe oxides/NC NPNCs). Remarkably, utilizing them as bifunctional catalysts, the assembled Ni2+ x Fe2- x N/NC||Ni2+ x Fe2- x N/NC electrolyzer only needs 1.51V cell voltage for driving OWS to approach 10mAcm-2 water-splitting current, exceeding their counterparts and the-state-of-art reported bifunctional catalysts-based devices, and Pt/C||IrO2 couples. Additionally, the Ni2+ x Fe2- x N/NC||Ni2+ x Fe2- x N/NC manifests excellent durability for OWS. The findings presented here may spur the development of advanced TMNs nanostructures by combining phase, structure engineering, and hybridization strategies and stimulate their applications toward OWS or other clean energy fields.

Toward high-power-density laser-driven lighting: enhancing heat dissipation in phosphor-in-glass film by introducing h-BN

In this work, hexagonal boron nitride (h-BN) nanocrystals as functional additives in a phosphor-in-glass film are shown to substantially increase the luminous performance driven by a blue laser. Microstructural and spectroscopic studies reveal that h-BN particles distributed over the whole glass matrix build in situ a local heat conductive path which effectively accelerates heat dissipation and so greatly relieves the "thermal run-away effect". The developed composite material with fine thermal manipulation may be a promising phosphor color converter for high-power-density laser-driven lighting.

The Chemistry of Cu3N and Cu3PdN Nanocrystals**

AbstractThe precursor conversion chemistry and surface chemistry of Cu3N and Cu3PdN nanocrystals are unknown or contested. Here, we first obtain phase‐pure, colloidally stable nanocubes. Second, we elucidate the pathway by which copper(II) nitrate and oleylamine form Cu3N. We find that oleylamine is both a reductant and a nitrogen source. Oleylamine is oxidized by nitrate to a primary aldimine, which reacts further with excess oleylamine to a secondary aldimine, eliminating ammonia. Ammonia reacts with CuI to form Cu3N. Third, we investigated the surface chemistry and find a mixed ligand shell of aliphatic amines and carboxylates (formed in situ). While the carboxylates appear tightly bound, the amines are easily desorbed from the surface. Finally, we show that doping with palladium decreases the band gap and the material becomes semi‐metallic. These results bring insight into the chemistry of metal nitrides and might help the development of other metal nitride nanocrystals.

The Chemistry of Cu3 N and Cu3 PdN Nanocrystals.

The precursor conversion chemistry and surface chemistry of Cu3N and Cu3PdN nanocrystals are unknown or contested. Here, we first obtain phase‐pure, colloidally stable nanocubes. Second, we elucidate the pathway by which copper(II) nitrate and oleylamine form Cu3N. We find that oleylamine is both a reductant and a nitrogen source. Oleylamine is oxidized by nitrate to a primary aldimine, which reacts further with excess oleylamine to a secondary aldimine, eliminating ammonia. Ammonia reacts with CuI to form Cu3N. Third, we investigated the surface chemistry and find a mixed ligand shell of aliphatic amines and carboxylates (formed in situ). While the carboxylates appear tightly bound, the amines are easily desorbed from the surface. Finally, we show that doping with palladium decreases the band gap and the material becomes semi‐metallic. These results bring insight into the chemistry of metal nitrides and might help the development of other metal nitride nanocrystals.