Honeycomb Nanostructures Research Articles

High-efficiency passivated emitter and rear cells with nano honeycomb structure

In this paper, a light-trapping nano honeycomb (NH) structure with a polyhedral interior was prepared on a c-Si wafer surface, which has a much lower reflectance and better passivation effect than that of a pyramid-textured surface. The NH structure was prepared using the metal-assisted chemical etching method together with the nanostructure rebuilding (NSR) method. Through reflectance measurement, internal quantum efficiency characterization and finite-difference time-domain simulation, the advantages of the NH structure were systematically studied. The formation mechanism of the NH structure was considered to be due to both the anisotropic and isotropic etching properties of Si crystal, and its main affecting factor was the NSR reaction time. To further demonstrate its potential in monocrystalline silicon cells, passivated emitter and rear cells (PERC) using NH-textured c-Si wafers were fabricated. A high efficiency of 22.80% was achieved, which was 0.3% and 0.16% higher compared to the normal upward pyramid-textured PERC and the inverted pyramid-textured PERC, respectively. The NH structure is expected to have a great potential application in the mass production of c-Si solar cells.

Honey-comb carbon nanostructure derived from peach gum to yield high microwave absorption

Lightweight and highly efficient electromagnetic absorptions are crucial for microwave absorption materials due to the fast development of information technology. Bio-derived carbon materials are ideal resistance loss-type microwave absorbers with lightweight. A honey-comb carbon structure has been obtained from peach gum by facile hydrothermal and pyrolysis processes. The skeleton of the as-derived honey-comb carbon structure is composed of carbon nanoparticles with diameters around 40 nm. The honey-comb structures were further carbonized at 850 °C (NPG-850) to have a large specific surface area of 1401.7 m2 g−1 with an average pore diameter of 3.2 nm. A minimum reflection loss (RL) of − 59.4 dB was obtained by NPG-850 at a thickness of 2.0 mm with an effective absorption bandwidth (EAB, RL < − 10 dB) of 4.1 GHz (14.7–10.6 GHz). The RL value of the peach gum-derived honey-comb carbon nanostructures is much higher than the reported carbon nanostructures even with thinner thickness and less mass loading, which might due to the multi-reflection effect of the honey-comb structures and the skeleton composition.

3D Honeycomb Nanostructure Comprised of Mesoporous N-Doped Carbon Nanosheets Encapsulating Isolated Cobalt and Vanadium Nitride Nanoparticles as a Highly Efficient Electrocatalyst for the Oxygen Reduction Reaction

The development of high-efficiency non-noble metal catalysts for the oxygen reduction reaction (ORR) is of paramount significance to sustainable energy-conversion technologies. Herein, a three-dime...

Low‐Temperature Synthesis of Honeycomb CuP2@C in Molten ZnCl2 Salt for High‐Performance Lithium Ion Batteries

AbstractPhosphorus‐rich metal phosphides have very high lithium storage capacities, but they are difficult to prepare. A low‐temperature phosphorization method based on Mg reducing PCl3 in ZnCl2 molten salt at 300 °C is developed to synthesize phosphorus‐rich CuP2@C from a Cu‐MOF derived Cu@C composite. Abnormal oxidation of Cu by Zn2+ in the molten salt is observed, which leads to the porous honeycomb nanostructure and homogeneously distributed ultrafine CuP2 nanocrystals. The honeycomb CuP2@C exhibits excellent lithium storage performance with high reversible capacity (1146 mAh g−1 at 0.2 A g−1) and superior cycling stability (720 mAh g−1 after 600 cycles at 1.0 A g−1), showing the promising application of P‐rich metal phosphides in lithium ion batteries.

Low-Temperature Synthesis of Honeycomb CuP2 @C in Molten ZnCl2 Salt for High-Performance Lithium Ion Batteries.

Phosphorus-rich metal phosphides have very high lithium storage capacities, but they are difficult to prepare. A low-temperature phosphorization method based on Mg reducing PCl3 in ZnCl2 molten salt at 300 °C is developed to synthesize phosphorus-rich CuP2 @C from a Cu-MOF derived Cu@C composite. Abnormal oxidation of Cu by Zn2+ in the molten salt is observed, which leads to the porous honeycomb nanostructure and homogeneously distributed ultrafine CuP2 nanocrystals. The honeycomb CuP2 @C exhibits excellent lithium storage performance with high reversible capacity (1146 mAh g-1 at 0.2 A g-1 ) and superior cycling stability (720 mAh g-1 after 600 cycles at 1.0 A g-1 ), showing the promising application of P-rich metal phosphides in lithium ion batteries.

Enlarged responsivity-ZnO honeycomb nanomaterials UV photodetectors with light trapping effect

The ability of ZnO photodetectors to absorb UV light plays a key role in enhancing responsivity and performance in electronic, optical, and photonic devices. Herein, the light trapping effect of ZnO is used to design and fabricate a novel honeycomb-like ZnO nanomaterial-based UV photodetector with an excellent photoelectric performance. Compared with the traditional ZnO film UV photodetector, the photoresponsivity of the film with honeycomb nanomaterials can reach up to 4.79 A W−1, which is an improvement of about 300 times. In addition, the honeycomb ZnO nanomaterials UV photodetectors exhibit an improved light absorption, a very photo-to-dark current ratio (2.46 × 103), and an excellent detectivity (4.61 × 1012 Jones). The ZnO honeycomb nanostructure synthesized in this work exhibits a strong trapping effect, providing new insights into the research of nanomaterials used for UV photodetectors.

Development of Reliable and High Responsivity ZnO-Based UV-C Photodetector

This work is focused on the development of reliable and high-performance ZnO based deep UV (UV-C) photodetectors. Herein, hydrothermally synthesized ZnO honeycomb nanostructures were utilized to develop a high sensitivity UV-C photodetector. A systematic analysis of the device performance and stability in deep UV (250 nm) radiations has been performed. The as-synthesized device has shown high sensitivity of 2.4 $\times \,\,10^{5}$ and responsivity of 597 A/W, at 20 V applied bias. Further, we have demonstrated that the coating of Pt nanoparticles over ZnO nanostructures could significantly improve not only the device stability but also the response speed and device endurance in deep UV radiations. The proposed device is a promising contender for future deep UV detector based optoelectronic products.

SEM and SPM Characterization of Nanostructures Formed by Anodizing Aluminum Foils

Scanning electron microscopy and scanning probe microscopy are used to examine the surface morphology of aluminum foils exposed to anodizing in acidic solution. Anodizing in the potentiostatic mode is shown to form a uniform honeycomb nanostructure on the foil surface, where the average distances between the centers of neighboring cells and the cell heights are proportional to the anodizing voltage. The specific electric capacitance of nanostructured anodic aluminum foils covered with an oxide layer via atomic layer deposition (ALD) is studied. The specific electric capacitance of nanostructured foils is established as a linear function of anodizing voltage and an inverse function of the number of ALD cycles.

Electron Depleted ZnO Nanowalls-Based Broadband Photodetector

Pristine ZnO has been extensively reported for high responsivity UV photodetectors based applications. However, in general, its photo-response in visible and NIR region is very poor. In this article, a simple and cost-effective technique of synthesizing pristine ZnO honeycomb nanostructure based high responsivity broadband (200 nm - 950 nm) photodetector is demonstrated. The dark current of the device was found to be as low as 5.6 pA at 10 V applied bias. The maximum photo-current to dark current ratio was $\sim 3.2 \times 10^{7}$ at 300 nm wavelength (measured at −10 V applied bias). The calculated linear dynamic range of the device is as high as 128.9 dB. The maximum specific photodetectivity, photoresponsivity and external quantum efficiency (@ 300 nm) calculated at −10 V bias was $2.07 \times 10^{15}$ cm $\cdot $ Hz $^{1/2} \cdot \text{W}^{-1}$ , 115 $\text{A}\cdot \text{W}^{-1}$ and 47,583% respectively, which is comparable to some of the existing commercial broadband photodetectors.

Enhanced ammonia recovery from wastewater by Nafion membrane with highly porous honeycomb nanostructure and its mechanism in membrane distillation

Removing nitrogen from wastewater by conventional treatment methods requires substantial energy, only to release it back to the atmosphere as gaseous nitrogen. Herein, we investigated the applicability of membrane distillation (MD) in resource recovery from sludge digestate by controlling the volatility and pressure of the vapor transport across the membrane to concentrate ammonia in the permeate stream. A mixture of Nafion ionomer and Multiwall Carbon Nanotubes (MWCNTs) were incorporated into a Poly (vinylidene fluoride-co-hexafluoropropene; PVDF-HFP) nanofiber matrix to fabricate a nanoporous honeycomb-structured Nafion membrane featuring high recovery and increased mechanical strength. Theoretical modeling was conducted to predict the expected performance of the fabricated Nafion membrane under different operation conditions and to reveal the mechanism behind the enhanced recovery of Nafion membranes in the MD process. The resultant Nafion (8%)/MWCNT (2.5%)/PVDF-HFP nanofibrous membrane demonstrated up to three times higher ammonia recovery, when compared to the commercial PVDF membrane, from a feed with an ammonia concentration of 300 mg/L. The theoretical analysis quantitatively revealed that the Nafion containing membrane can not only suppress the negative effect of membrane's structural resistance on the ammonia recovery efficiency but also enhance the efficiency. In addition, we also uncovered that the effect of Nafion on ammonia recovery efficiency was maximized when the Nafion 8% membrane was employed. This study demonstrated an innovative and realistically applicable MD treatment process for recovering resource, which integrates low-grade heat and has the potential to scale-up for use in wastewater treatment plants.

Aggregation and Tunable Color Emission Behaviors of l-Glutamine-Derived Platinum(II) Bipyridine Complexes by Hydrogen-Bonding, π-π Stacking and Metal-Metal Interactions.

An l-glutamine-derived functional group was introduced to the bis(arylalkynyl)platinum(II) bipyridine complexes 1-4. The emission could be switched between the 3 MLCT excited state and the triplet excimeric state through solvent or temperature changes, which is attributed to the formation and disruption of hydrogen-bonding, π-π stacking, and metal-metal interactions. Different architectures with various morphologies, such as honeycomb nanostructures and nanospheres, were formed upon solvent variations, and these changes were accompanied by 1 H NMR and distinct emission changes. Additionally, yellow and red emissive metallogels were formed at room temperature due to the different aggregation behaviors introduced by the substituent groups on bipyridine. The thermoresponsive metallogel showed emission behavior with tunable colors by controlling the temperature. The negative Gibbs free-energy change (ΔG) and the large association constant for excimer formation have suggested that the molecules undergo aggregation through hydrogen-bonding, π-π, and metal-metal interactions, resulting in triplet excimeric emission.

Smart NIR-Light-Mediated Nanotherapeutic Agents for Enhancing Tumor Accumulation and Overcoming Hypoxia in Synergistic Cancer Therapy.

The efficacy of photodynamic therapy (PDT) still shows limited success in clinical application due to hypoxia in the solid tumor, low tumor accumulation and limited light penetration depth of photosensitizers (PS). The previously reported MnO2-based nanotherapeutic agents always required intratumoral injection or complex targeting modification process to improve the therapeutic efficacy. Herein, new MnO2-based nanotherapeutic agents (honeycomb MnO2/IR780/BSA nanoparticles, HMIB NPs) are designed and prepared to achieve excellent phototherapeutic performance characterized by NIR-light-mediation, deep diffusion via TME response and O2 self-supply. The ex vivo and in vivo NIR fluorescence imaging results demonstrate that the honeycomb nanostructure of HMIB NPs facilitates the high tumor accumulation of hydrophobic IR780 via enhanced permeability and retention (EPR) effect after intravenous injection. The immunofluorescence results demonstrate that the TME response of HMIB NPs not only provides O2 for relieving hypoxia but also reduces size for improving deep intratumoral diffusion. As a result, under the synergy of NIR fluorescence imaging, photothermal effect and PDT of IR780 with TME responsive size-change, and O2 self-supply of honeycomb MnO2, the HMIB NPs have achieved all-in-one NIR fluorescence and photothermal dual-model imaging guided synergistic PDT/PTT under a single-wavelength NIR light irradiation.

3D honeycomb nanostructure-encapsulated magnesium alloys with superior corrosion resistance and mechanical properties

Magnesium (Mg) alloys are promising biodegradable metals for biomedical applications but limited by their too fast degradation rates. In this study, selective laser melting was used to fabricate three-dimensional honeycomb nanostructure-encapsulated Mg alloys, in which the honeycomb nanostructure was constructed by graphene oxide (GO) as a second phase and the grains of Mg alloys were encapsulated in the honeycomb unit. Results showed that GO distributed along the grain boundaries and gradually wrapped ɑ-Mg grains as GO content increasing. It was worth noting that a honeycomb nanostructure was formed with ɑ-Mg grains encapsulated in the honeycomb unit at a certain GO content (1.0 wt% in this study). As a result, the corrosion resistance and mechanical properties were both improved, which might be ascribed to the following mechanisms: (I) ɑ-Mg grains were refined due to the reduced connection and promoted nucleation by GO; (II) Benefiting from the outstanding anti-permeability of GO, the honeycomb nanostructure acted as a tight barrier to restrain the propagation of corrosion; (III) GO reinforced the corrosion layer to prevent it falling off the Mg matrix; (Ⅳ) The oxygen-containing groups on GO facilitated the deposition of bone-like apatite and further hindered the invasion of corrosive medium. These findings demonstrated the multiple defensive roles against corrosion in the honeycomb nanostructure-encapsulated Mg alloys and their great potential in biomedical applications.

Dual Biosensor Coupling with Localized Surface Plasmon Resonance and QCM-D Using Nano-honeycomb Structure

It is very important to understand molecular interaction and deformation for chemistry, biochemistry, drug discovery, and so on. We introduced a biosensing device which could detect mass change, viscoelasticity change, and refractive index change at a time. The device had nanosized honeycomb structure which was formed by a self-organizing process on anodization of Al. As a first examination, we show the results of adsorption of protein to the device surface

Systematic investigations on the effect of prolong UV illumination on optoelectronic properties of ZnO honeycomb nanostructures

Herein, the effect of prolong UV illumination over ZnO optoelectronic characteristics has been investigated. The photoluminescence analysis has shown significant enhancement in deep level emission (DLE) after sample being exposed to UV radiations. The formation of photo-induced oxygen vacancies (VO) over the ZnO surface was found to be responsible for such noteworthy enhancement in DLE. The observed phenomenon was further utilized for controlled incorporation of VO in ZnO via UV illumination, towards obtaining optimal device performance. The UV treated photo-detector has shown significantly high photo-responsivity and photo-sensitivity in the deep UV region.

Controllable morphologies and electrochemical performances of self-assembled nano-honeycomb WS2 anodes modified by graphene doping for lithium and sodium ion batteries

Self-assembled nano-honeycomb WS2 modified by graphene doping were prepared by improved one step hydrothermal method. In this hybrid structure, graphene plays a key role of transferring the morphology from the nanowire microporous spheres to graphene-supported nano-honeycomb plane structure, which has the larger the specific surface area and higher conductivity. This anode delivers the superb electrochemical performances of lithium/sodium ion batteries with high specific charge capacity (953.1/522.3 mAh·g−1 at 0.1 A·g−1), long cycling life (more than 350/200 cycles at 1 A·g−1), and high charge/discharge rates (up to 10/5 A·g−1). This nano-honeycomb structure WS2 composite anode with facile hydrothermal process, as well as superb electrochemical performances, makes it attractive for the potential applications in lithium/sodium ion batteries.

Zinc Interstitial Rich ZnO Honeycomb Nanostructures for Deep UV Photodetection

Pristine ZnO nanostructures (NSs) are less sensitive to deep UV radiations, which restrict their usage to near UV region only. In order to extend its usability in deep UV region; Zn interstitial rich honeycomb (HC) NSs of ZnO is developed. The device shows remarkably high photoresponsivity of 1150 A W−1 in deep UV region (λ = 254 nm). Additionally, enhanced deep UV photosensitivity is observed and can be attributed to the incorporation of Zn ions in ZnO lattice and large surface to volume ratio of HC NSs. Furthermore, in dark conditions, the width of the depletion region is comparable to the thickness of HC NSs (20 nm) that results in complete depletion of charge carriers in NSs, which results in significant reduction in dark current. Moreover, HC NSs are provided continuous conduction path which eliminates the potential barrier forming at the NSs interfaces, resulting in efficient charge transportation. The measured photocurrent to dark current ratio is as large as ≈6 orders of magnitude. Such large photosensitivity in the deep UV region of electromagnetic spectrum makes these devices a promising candidate for development of deep UV photo‐detectors for commercial applications.

Terahertz vibrational signature of bacterial spores arising from nanostructure decorated endospore surface.

This theoretical effort is the first to explore the possible hypothesis that terahertz optical activity of Bacillus spores arises from normal vibrational modes of spore coat subcomponents in the terahertz frequency range. Bacterial strains like Bacillus and Clostridium form spores with a hardened coating made of peptidoglycan to protect its genetic material in harsh conditions. In recent years, electron microscopy and atomic force microscopy has revealed that bacterial spore surfaces are decorated with nanocylinders and honeycomb nanostructures. In this article, a simple elastic continuum model is used to describe the vibration of these nanocylinders mainly in Bacillus subtilis, which also leads to the conclusion that the terahertz signature of these spores arises from the vibration of these nanostructures. Three vibrating modes: radial/longitudinal, torsional and flexural, have been identified and discussed for the nanocylinders. The effect of bound water, which shifts the vibration frequency, is also discussed. The peptidoglycan molecule consists of polar and charged amino acids; hence, the sporal surface local vibrations interact strongly with the terahertz radiation.

Wettability of porous anodic aluminium oxide membranes with three-dimensional, layered nanostructures

The architecture-dependent wettability of three-dimensional (3D), porous anodic aluminium oxide (AAO) membranes with varying surface morphologies including hierarchical, mesh and honeycomb nanostructures is reported. The surface morphology and underlayer structure play different roles in regulating the wetting behaviour of the AAO membranes. For the mild AAO membranes, the wetting behaviour of the ultra-thin top layer is dominated by the surface morphology in which the water contact angles (WCAs) of the AAO membranes with hierarchical, mesh and honeycomb structures are approximately 113.7° ± 4.6°, 94.9° ± 0.7° and 98.8° ± 5.8°, respectively. The wetting behaviour of the 3D, layered AAO membranes is dominated by both the surface morphology and the underlayer structure. Notably, the WCA of the mild AAO membrane with a layered hierarchical structure increases in the second layer (increase in the hole density). The WCAs of the three kinds of layered hard AAO membranes decrease in the second layer (increase in the hole depth) and then decrease slowly or increase in the third transition layer (decrease in the hole density). The WCAs of all the AAO membranes decrease linearly at different rates with the formation of the ordered bottom layer. The above results can facilitate the engineering of nanostructures for controlling the surface wetting behaviour of materials and devices for applications in multiple fields.

Biomimetic plasmonic color generated by the single-layer coaxial honeycomb nanostructure arrays

Biomimetic plasmonic color generated by the single-layer coaxial honeycomb nanostructure arrays