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The effect of nano-scaled Si3N4 particles on the microstructure, mechanical and electrochemical behavior of hopeite (Zn3(PO4)2·4H2O) conversion coating on pure titanium was investigated. Different concentrations of nanoparticles were dispersed into the phosphating bath to incorporate the process of coating deposition. The XRD results demonstrated that nano-Si3N4 were doped into the coatings without any decomposition or reaction with the hopeite phase. A finer and denser microstructure of the composite coating could be obtained at the addition of 0.5 g/L Si3N4 in comparison with the pure hopeite coating. Moreover, the composite coating presented a higher bonding strength and corrosion resistance related to the refinement of microstructure and filling of the embedded nanoparticles. It is suggested that the incorporation of nano-Si3N4 particles in conversion coating is a promising approach for performance optimization.

Strontium (Sr) can be introduced into hydroxyapatite (HA) crystals and stimulate new bone formation. In this study, the single-crystalline Sr-substituted HA microtubes with hexagonal cross-sections are synthesized under the regulation of Sr2+ via the oleic acid-assisted solvothermal method. The morphology of the as-prepared products changes from ultralong flexible nanofibers to hexagonal microtubes with the increasing Sr/(Sr + Ca) ratio. Microtubes can be formed when a small amount of Sr is doped into HA, with the optimal substitution ratio of Sr2+ being ~6%. The inner and outer diameters of the synthetic Sr-substituted HA microtubes are about 1.6 and 2.3 μm, respectively. Moreover, the effects of Sr2+ dopping on the formation process and mechanism of microtubes were discussed.

Room-temperature photoluminescence enhancement of molybdenum disulfide (MoS2) monolayers on epitaxial titanium nitride (TiN) thin films grown by molecular-beam-epitaxy as well as magnetron-sputtered TiN films is observed by a confocal laser scanning microscope with excitation wavelengths covering the transition of TiN's macroscopic optical properties from dielectric to plasmonic. The photoluminescence enhancement increases as TiN becomes more metallic, and strong enhancement is obtained at the excitation wavelengths equal to or longer than the epsilon-near-zero (ENZ) wavelength of TiN films. A good agreement is observed between measured and calculated enhancements. The enhancement is attributed to the increased excitation field in MoS2 at TiN's ENZ wavelength and interference effects for thick spacers that separate the MoS2 flakes from TiN films in the metallic regime. This study enriches the fundamental understanding of emission properties on ENZ substrates that could be important for the development of advanced nanoscale lasers/light sources, optical/biosensors, and nano-optoelectronic devices.

We presented and demonstrated a new type of vertical nanowire (NW) and nanosheet (NS) field-effect transistors (FETs), named vertical sandwich gate-all-around FETs or VSAFETs, which were formed with the process compatible in the main stream industry. The VSAFETs with self-aligned high- ${k}$ metal gates (HKMGs) were fabricated with epitaxy of Si/SiGe/Si sandwich structure, an isotropic quasi-atomic-layer-etch (qALE) process, and gate replacement process. The gate-length of VSAFETs is mainly determined by the thickness of SiGe film grown by epitaxy. The NW diameter and NS thickness could be obtained by the isotropic qALE method, which can be used to the Si-selective etching of SiGe. As a result, p-type NS and NW VSAFETs with good device characteristics were fabricated. Device performance and the influence of silicide, Ge fraction, Si cap, and high thermal process were investigated; threshold voltage tuning and reliability were also discussed.

Simply constructing multiple responsive polymers with obvious shape and dimension variations on their assemblies upon different stimuli is still rarely reported. In this study, we report a hyperbranched polymer named HPAzoBAHB-star-PEG9 with quadruple-response to light, temperature, pH and oxidation stimuli. The polymer contains azobenzene chromophore, sulfide, amide and amine groups in its hydrophobic hyperbranched core, and the core is capped with hydrophilic polyethylene glycol (PEG9) arms. HPAzoBAHB-star-PEG9 could assemble into unusual leaf-like lamellar micelles at 25 °C under the guidance of orderly arranged H-aggregate of azobenzene moieties. These leaf-like lamellar micelles can transform into vesicles upon UV irradiation and lower temperature, or convert to smaller spherical micelles in acidic or oxidative environments, respectively, with the destroy of ordered azobenzene arrangements. This quadruple-responsive hyperbranched polymer is suitable to construct multiple stimuli-responsive micro/nanostructures, or accurate delivery and release following subtle stimuli sequences.

Flexible electronics has recently captured extensive attention due to its intriguing functionalities and great potential for influencing our daily life. In addition, with the increasing demand for green energy, photoelectrochemical (PEC) water splitting is a clean process that directly converts solar energy to chemical energy in the form of hydrogen. Thus the development of flexible green energy electronics represents a new domain in the research field of energy harvesting. In this work, we demonstrate the BiVO4 (BVO)/WO3/ITO/muscovite heterostructure photoelectrode for water splitting with flexible characteristics. The performance of BVO was modified by specific crystal facets, and the BVO/WO3 bilayer exhibited superior performance of 33% enhanced PEC activity at 1 V vs Ag/AgCl compared with pure BVO due to the proper staggered band alignment. Moreover, excellent mechanical stability was verified by a series of bending modes. This study demonstrates a pathway to a flexible photoelectrode for developing innovative devices for solar fuel generation.

Monolayer transition metal dichalcogenides (TMDs), direct bandgap materials with an atomically thin nature, are promising materials for electronics and photonics, especially at highly scaled lateral dimensions. However, the characteristically low total absorption of photons in the monolayer TMD has become a challenge in the access to and realization of monolayer TMD-based high-performance optoelectronic functionalities and devices. Here, we demonstrate gate-tunable plasmonic phototransistors (photoFETs) that consist of monolayer molybdenum disulfide (MoS2) photoFETs integrated with the two-dimensional plasmonic crystals. The plasmonic photoFET has an ultrahigh photoresponsivity of 2.7 × 104 AW-1, achieving a 7.2-fold enhancement in the photocurrent compared to pristine photoFETs. This benefits predominately from the combination of the enhancement of the photon-absorption-rate via the strongly localized-electromagnetic-field and the gate-tunable plasmon-induced photocarrier-generation-rate in the monolayer MoS2. These results demonstrate a systematic methodology for designing ultrathin plasmon-enhanced photodetectors based on monolayer TMDs for next-generation ultracompact optoelectronic devices in the trans-Moore era.

Hyperbolic metamaterials (HMMs) possess marvelous electromagnetic properties, which enable a wide variety of applications, such as super-resolution and spontaneous emission. In addition, HMMs have ...

The outstanding properties of perovskites have attracted huge attention in optoelectronic applications. However, the current study mainly focuses on small-area single-layer perovskite films. Surfac...

In this study, we achieved a facile and low-cost (18-22 USD/g) synthesis of spiro[fluorene-9,9-phenanthren-10-one]-based interfacial layer materials (MSs; designated MS-PC, MS-PA, MS-OC, and MS-OA). Carbazoles and dimethylacridine substituents with an extended π-conjugation achieved through ortho- or para-orientations were used as donors at the spiro[fluorene-9,9'-phenanthren-10'-one] moiety. Highly efficient and stable inverted perovskite solar cells (PSCs) with the device architecture of ITO/NiOx/MSs/perovskite/PC61BM/BCP/Ag can be achieved to improve the surface morphology of NiOx when MSs are adopted as the interfacial layer. During a morphological study, the ortho-orientated donor of MS-OC and MS-OA has spherical structures indicated that the films were smooth and that the films of perovskite deposited on them had large grain size and uniformity. The photoluminescence properties of the perovskite layers on the NiOx/MSs were showed better hole-transporting capabilities than the bare NiOx. The dual-functional interfacial layer has shown defect passivation effect, it not only improved the surface morphology of NiOx but also enlarged the perovskite layer grain size. The best PSC device performance of the NiOx/MS-OC was characterized by 22.34 mA cm-2 short-circuit current density (Jsc), 1.128 V open-circuit voltage (Voc), and 80.8% fill factor (FF), resulting in 20.34% power conversion efficiency (PCE). The NiOx/MS-OC PSCs showed good long-term device stability, even retained the original PCE of 93.16% after 370 days under argon (25 °C). Owing to the superior perovskite morphologies of the NiOx/MSs, the resulting devices outperformed the bare NiOx-based PSCs.

An intrinsic {0001} GaN wafer cut to expose the {100}/{100} side faces allows examination of its conductivity properties with respect to the crystal faces. Interestingly, the {100} face shows a 10-fold higher photoluminescence peak intensity than the {0001} face. The {0001} face is 60-fold more conductive at 6 V than the {100} face, demonstrating the presence of an electrical facet effect. The conductivity difference can be rationalized assuming different degrees of band bending at these crystal surfaces. Asymmetric I–V curves were obtained with electrical connections made to both faces simultaneously, showing the potential of using this behavior to fabricate transistors.

In this work, copper (Cu2+) substituted zinc ferrite (CuxZn1-xFe2O4 (0 ≤ x ≤ 1)) hollow micro-nanospheres were synthesized using a facile solvothermal and annealing technology. We investigated the effects of Cu2+ substitution on morphology, structure and gas sensing properties of CuxZn1-xFe2O4 hollow micro-nanospheres. The results confirmed the successful substitution of Zn2+ with Cu2+ and the cations redistribution. In addition, the testing results revealed that CuxZn1-xFe2O4 (0.25 ≤ x ≤ 1) based sensors showed significantly enhanced responses to low concentration acetone vapor. Especially, Cu0.75Zn0.25Fe2O4 and CuFe2O4 displayed high responses of 2.37 and 2.43 to 0.8 ppm acetone at 125 °C respectively, while that of ZnFe2O4 was only 1.17. Moreover, CuFe2O4 demonstrated an excellent sensor response, ultra-low limit of detection and remarkable selectivity. The fast response speed and high stability of CuFe2O4 sensor further indicated that it was promising to apply for practical medical diagnosis. The enhanced sensing properties of Cu0.75Zn0.25Fe2O4 and CuFe2O4 sensors were explained by the effect of Cu2+ on lattice cation distribution, electron depletion layer thickness and adsorbing capacity.

Soluble covalent organic cages (COCs) were designed to comprise cryptand inner cavities and multiple metal-chelating sites on windows. The porous liquid formed by well-dispersed COCs in solution pr...

The operation characteristics of polycrystalline Si (poly-Si) gate-all-around (GAA) junctionless (JL) charge-trapping (CT) flash memory devices with the Zr-based stacked trapping layer were studied in this work. Devices with the Si3N4/ZrO2 stacked trapping layer show enhanced erasing speeds and comparable retention characteristics in comparison to Si3N4/HfO2 due to many shallow energy traps and smaller valance band offset in the ZrO2 layer. By inserting Al2O3 between Si3N4 and ZrO2 trapping layer, the retention and endurance characteristics are improved. The erasing speed can be further improved by a Zr-rich oxide layer near the tunneling oxide since the energy barrier can confine more injected electrons near the tunneling oxide. The retention characteristic can be improved without sacrificing the erasing speed because some of the shallow traps can be passivated by NH3 plasma treatment on ZrO2. Hence, the ZrO-based stacked trapping layer is very promising for the poly-Si GAA JL CT flash devices for nonvolatile memory applications.

In this study, graphene oxide (GO) nanosheets were modified with an amine functional group to obtain amine-functionalized graphene (AMG) nanosheets and then blended with the aniline curing agent of bisphenol-A (BPA) epoxy resin to crosslink BPA epoxy resin. The AMG-blended curing agent and BPA epoxy resin formed an intermolecular hydrogen bond that was stronger than the π–π stacking force between benzene rings of graphene nanosheets. Therefore, AMG nanosheets exhibited excellent dispersion in the aniline curing agent. The amine group of AMG-blended curing agents and the epoxy functional group of BPA epoxy resin exhibited strong chemical activity and underwent crosslinking and polymerization. AMG nanosheets were mixed with BPA epoxy resin to form a crosslinked structure through the epoxy ring-opening polymerization of the resin. The mechanical properties of the epoxy resin nanocomposites were significantly improved by the added 1 wt.% AMG nanosheets. The tensile strength was enhanced by 98.1% by adding 1 wt.% AMG in epoxy. Furthermore, the impact resistance of the epoxy resin was enhanced by 124.4% after adding 2.67 wt.% of AMG nanosheets. Compared with other reinforced fillers, AMG nanosheets are very light and can therefore be used as nanocomposite materials in coating applications, the automotive industry, aerospace sheet materials, wind power generation, and other fields.

Hydrothermal methods are widely used in chemical synthesis of target products with specific morphology and nanostructure. Those methods are very efficient for the preparation of well-controlled structures but the reaction time is usually long. The assistance of microwave makes the reaction system heat up faster, more uniformly and reactions are accelerated, it also can be utilized to change the morphology or structure of materials, which improves the physic-chemical properties of synthesized products and influences its gas-sensing performance. Copper oxide (CuO) is widely applied in semiconductor gas sensors because of its good reactivity and stability. This review article briefly introduces the principle, mechanism and recent development of CuO nanostructures obtained by microwave-assisted hydrothermal synthesis (MWHS) process. It also discussed the relation between endopathic factors of material and its gas-sensitive performance. The technical challenges and prospective solutions for high-performance CuO-based gas-sensitive materials with unique nanostructure are proposed. It is pointed out that the hierarchical CuO-based nanostructures and their composite materials prepared by MWHS process are efficacious methods to improve the gas-sensitive performance of the materials. On the basis of the morphology, the materials are divided into nanorods, nanoflowers, nanosheets, nanospheres and other nanostructures. The influence of microwave parameters on the properties of synthetic products is analyzed. The influence followed by metal element loading on the structure and properties of CuO-based materials by MWHS process is further discussed. Then this review summarizes the research progress of graphene-CuO and metal oxide-CuO composites prepared by MWHS process in recent years.

Herein, core-twisted tetrachloroperylenediimides (ClPDIs) were introduced as new efficient electron-transporting materials (ETMs) to replace the commonly used fullerene acceptor PC61 BM in inverted planar perovskite solar cells (PSCs). ClPDI showed a low-lying lowest unoccupied molecular orbital (LUMO) energy level of -3.95 eV, which was compatible with the conduction band of CH3 NH3 PbI3-x Clx (-3.90 eV). In addition, the role of the length of the alkyl side chain at the imide position of ClPDI in modulating the molecular solubility, aggregation capacity for charge-transport properties, surface hydrophobicity, and PSC performance was investigated. The device based on ClPDI-C4 (ClPDI with n-butyl side chains) as ETM achieved a maximum power conversion efficiency (PCE) of 17.3 % under standard AM 1.5G illumination, which iwas very competitive with that of the reference device employing PC61 BM/C60 (PCE=17.2 %) as ETM. Moreover, the devices with ClPDIs as ETMs exhibited better device stability than that with PC61 BM/C60 . This work highlights the great potential of ClPDI derivatives as low-cost (≈2.0 USD g-1 ) and effective ETMs to obtain efficient solution-processed inverted PSCs. This class of ClPDI derivatives is expected further promote the performance and stability of PSCs after extended investigation.

In view of the polyvinyl chloride (PVC) in the processing and molding easy degradation, the stability effect of different components is not good when used alone, and PVC in thermal degradation with the release of hydrogen chloride will lead to the formation of toxic gas dioxins to the environment and human problems. For this purpose, the nanosized titanium dioxide (NT), calcium–zinc (Ca-Zn)*, dipentaerythritol (Dip) and organotin (OT) were modified with butyl titanate (BT), coupling agent to synthesize the composite material and used as the strengthening agent for PVC. The composites and PVC were characterized, and their properties were determined using Raman, XRD, TG, TG-IR, Congo red and DMA. The results showed that the BT/NT/Dip/OT/(Ca-Zn)* complex not only kept the basic configuration of NT particles, but also had strong interaction between components due to BT coupling, which had synergistic effect on PVC. Similarly, BT was involved in the coupling between PVC and Dip/OT, resulting in prolonged initial discoloration time. When 3.8mass%BT/NT, 0.32mass%OT, 0.32mass%(Ca-Zn)* and 0.63mass% Dip were added to the PVC film, compared with blank sample and only 1phr of OT stabilizer, the new composite material was formed. The longest initial discoloration time was observed by Congo red, and the temperature was improved when TG was used to analyze the maximum mass loss rate, and the maximum mass loss rate was reduced by 115%. As the conversion rate reached 1%, the decomposition temperatures of PVC composite film and blank sample were 234.7 °C and 175.2 °C, respectively, indicating that the formed PVC film had excellent thermal stability. TG-FTIR analysis showed that after adding OT at 0.5 phr, (Ca-Zn)* at 0.5 phr and Dip at 1.0 phr, the composite film was around 331.1 °C and 476.6 °C, and the peak strength of CH4 gas released by thermal degradation was 114.0 and 262.0% higher than that of blank sample, respectively. It can be seen that pentaerythritol has a promoting effect on CH4 release of PVC, and the peak strength of CO2 is shifted to the high temperature zone, contrary to the blank sample, there is no formation of hydroxyl or water, which means that the thermal degradation pathway of PVC has changed, and it is possible to inhibit the generation of aromatic hydrocarbons and dioxins. By introducing 3.8 mass% BT/NT composite reinforcement, compared with the blank sample, the observed storage modulus increased by 22.4%, and the mechanical properties of PVC composite material were improved.

Excitons in monolayer transition metal dichalcogenides (TMDs) have exceptionally large binding energies and dominate the optical properties of materials. Exploring the relaxation behavior of excitons is crucial for understanding the fundamental physics as well as the performance of TMD-based optoelectronic devices. However, ultrafast carrier dynamics is sensitive to the structural defects and surface conditions of TMDs, depending on the growth or transfer process. Here, we utilized pump-probe transient absorption (TA) spectroscopy with a white-light probe to investigate the dynamics of excitons in monolayer MoS2 synthesized by the metal sulfurization method. The sulfurization method was used for the fabrication of large-scale, continuous, and uniform thin films with a controllable number of layers. The excitation dynamics of the wafer-size monolayer MoS2 is found to be comparable to that of monolayer MoS2 flakes grown by chemical vapor deposition (CVD). The dominant processes of carrier relaxation in the monolayer MoS2 are exciton–exciton annihilation (hundreds of femtoseconds), the trapping of the excitons by surface states (a few picoseconds), and interband carrier-phonon scattering (tens of picoseconds). Moreover, the induced absorption due to mid-gap defects, which is often observed for samples fabricated by growth methods, such as CVD, is not observed for our continuous and uniform monolayer films. Understanding the charge carrier dynamics of the exciton in the scalable and uniform monolayer MoS2 can provide physical insights that are valuable in the design and development of complex 2D devices.

A novel coating method of transforming scholzite (SZ, CaZn2(PO4)2·2H2O) into hydroxyapatite (HA, Ca10(PO4)6(OH)2) coating on the surface of titanium (Ti) has been presented. It deposited a primary SZ coating through a phosphate chemical conversion (PCC) technology, and then transformed it to the HA coating via calcium (Ca) chelating. FE-SEM and XRD results proved that a nanostructured HA coating with a cauliflower-like shape and without zinc (Zn) element doping could be obtained from the primary petal-like SZ coating. It suggests that SZ may act as a simple and effective intermediate for HA precipitation. The electrochemical impedance spectroscopy (EIS) test was employed to evaluate the corrosion behavior of the coated samples in simulated body fluid (SBF). The results showed that the HA-coated sample obtained by Ca chelating post-treatment exhibited improved barrier performance compared with the primary SZ-coated one.

In the current study, a predictive model on tool flank wear rate during ultrasonic vibration-assisted milling is proposed. One benefit of ultrasonic vibration is the frequent separation between too...

An acceptor-donor-acceptor (A-D-A)-type non-fullerene acceptor (NFA), PTTtID-Cl, featuring thieno[3,2-b]thieno[2''',3''':4'',5'']-pyrrolo[2'',3'':4',5']thieno[2',3':4,5]thieno-[2,3-d]pyrrole (DTPTt) as the electron-rich core and 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (ID-Cl) as the peripheral electron-deficient terminal group was synthesized and characterized. PTTtID-Cl exhibited strong absorption in the range of 700-850 nm in CHCl3 and redshifted absorption centered at 881 nm in a thin film. The near infrared (NIR)-absorption of PTTtID-Cl was combined with a low-bandgap polymer donor (PTB7-Th) to achieve binary and semitransparent organic photovoltaics (OPVs) with a power conversion efficiency (PCE) of 8.9 % and 7.7 % (with an average visible transmittance (AVT) of 16.7 %), respectively. A ternary device with a ratio of PM7/PTTtID-Cl/IT-4F=1:0.15:0.85 (w/w) achieved a short-circuit current density of 19.46 mA cm-2 , an open-circuit voltage of 0.87 V, and a fill factor of 71.2 %, giving a PCE of 12.0 %. In addition, by employing the Ag/ITO/Ag microcavity structure, semitransparent colorful binary organic photovoltaics (OPVs) with superior transparency of 27.9 % at 427 nm and 22.7 % at 536 nm for blue and green devices, respectively, were prepared. The semitransparent colorful devices based on the optimized ternary blend gave PCEs of 8.7 %, 8.4 %, and 9.1 % for blue, green, and red devices, respectively. These results indicate the promising potential of PTTtID-Cl as a NIR-absorption NFA for applications in semitransparent colorful binary and ternary OPVs.

In laser-assisted milling, higher temperature in shear zone softens the material potentially resulting in a shift of mean residual stress, which significantly affects the damage tolerance and fatigue performance of product. In order to guide the selection of laser and cutting parameters based on the preferred mean residual stress, inverse analysis is conducted by predicting residual stress based on guessed process parameters, which is defined as the forward problem, and applying iterative gradient search to find process parameters for next iteration, which is defined as the inverse problem. An analytical inverse analysis is therefore proposed for the mean residual stress in laser-assisted milling. The forward problem is solved by analytical prediction of mean residual stress after laser-assisted milling. The residual stress profile is predicted through the calculation of thermal stress, by treating laser beam as heat source, and plastic stress by first assuming pure elastic stress in loading process, then obtaining true stress with kinematic hardening followed by the stress relaxation. The variance-based recursive method is applied to solve inverse problem by updating process parameters to match the measured mean residual stress. Three cutting parameters including depth of cut, feed per tooth, and cutting speed, and two laser parameters including laser-tool distance and laser power, are updated with respected to the minimization of resulting residual stress and measurement in each iteration. Experimental measurements are referred on the laser-assisted milling of Ti-6Al-4V grade 5 and ELI. The percentage difference between experiments and predictions is less than 5% for both materials, and the selection is completed within 50 loops.

From theoretical calculations, simulations, and emulations, as well as laboratory testing, we evaluated the influences of both diamond and diamond-film-coated support rods, as well as diamond-film-coated helices, on the heat dissipation capabilities of slow wave structures (SWSs). A comparison between the experiment and simulation data shows that the computer simulation results are in good agreement and offer an important reference for the application of diamond in SWSs. An expression for the coefficient of thermal conductivity for the helix material and for the support rod material indicates that the greater their value, the better the heat dissipation capability of the helical SWS. The simulation and emulation analysis results show that when the helix reaches the same temperature, SWSs made of diamond-film-coated support rods and helix are able to consume 20%–60% more heating power than normal SWSs. Similar to a purely diamond support rod, a diamond-film-coated helix and support rod are able to improve the heat dissipation capabilities of SWSs effectively. In experiments, we tested the heat dissipation capabilities of SWSs with their helix surfaces plated with high-performance gold/copper films and BeO/BeN support rods. The experimental results agree well with the ANSYS simulation and emulation results.

Photophobic (white) films were prepared by mixing hydroxypropyl methylcellulose (HPMC) of different molecular weights with sodium citrate (SC). Wide angle X-ray diffractometry, small angle X-ray scattering, scanning electron microscopy, dynamic mechanical analysis, whiteness determination and texture analysis were used to investigate the effect of HPMC molecular weight on the aggregation structures and properties of HPMC film. The crystalline integrity decreased with the increased molecular weight of HPMC for these HPMC/SC films. Similar crystallinity was observed for 6HPMC/SC and 15HPMC/SC, which was larger than that of 50HPMC/SC. All the three HPMC/SC film showed surface fractal structure with similar Ds. With the increasing molecular weight of HPMC, the HPMC/SC film showed honeycomb structures with smaller holes and more compact porous structure, Tg first increased and then decreased a little, the tensile strength and elongation increased with the increasing HPMC molecular weight. 50HPMC/SC films with the smallest pores showed the largest whiteness. A new Tg' peak was observed for HPMC/SC film.

Using titanium (Ti) for clinical implants often requires surface modification to improve long-term stability and biological activity. However, due to the presence of stable oxide film, modifying the surface of Ti by chemical conversion is difficult. In this research, an electro-assisted method was used to rapidly form chemical transformation coatings on Ti. The effects of Fe2+ and temperature on the phase composition, microstructures, properties, and the formation mechanism of coatings were investigated. The temperature affected the hydrogen evolution by changing the overpotential of hydrogen, thereby affecting the composition of the coatings. The coatings formed at 60 °C were mainly composed of hopeite, whereas those formed at 30 °C mainly composed of elemental zinc (Zn). Fe2+ promoted the reduction of Zn2+ by abnormal co-deposition with Zn2+ and then changed the morphology and properties of the conversion coating.

The low vessel density and oxygen concentration in hypoxia are the main causes of reduced efficiency of anticancer therapeutics and can stimulate the tumor's relapse. Research showed that macrophages could cross the blood-vessel barriers and reach the hypoxic regions of tumors. Using macrophages in a drug delivery system has been a promising method for tumor targeting in recent years. In this work, we successfully modified monocyte chemoattractant protein-1 (MCP-1) and iron-based metal-organic framework (MIL-100(Fe)) on the photothermal agent, gold nanorods (GNRs) (i.e., MCP-1/GNR@MIL-100(Fe)), to increase cellular uptake and biocompatibility. The results of TEM, UV-vis, and FTIR all confirmed that we'd synthesized MCP-1/GNR@MIL-100(Fe) successfully, and the MCP-1/GNR@MIL-100(Fe) also showed good biocompatibility. A transwell migration assay illustrated that our material attracted macrophages, and the material uptake amount was increased by 1.5 times after MCP-1 functionalization. It also indicated that the macrophages have a tumor-targeting ability. In the in vivo experiment, we subcutaneously implanted U251 MG cells in nude mice as a xenograft model to demonstrate the photothermal activity of MCP-1/GNR@MIL-100(Fe). With successive NIR treatment, the tumor growth could be controlled, and the tumor volume still remained below 100 mm3 after laser treatment. MCP-1/GNR@MIL-100(Fe) combined with the laser treatment showed an excellent antitumor efficacy from the histology of tumor tissues, survival rates, and bioluminescence imaging.

We present a high-energy wet-milling grinding method to prepare the NiO NPs at a room temperature and a low-temperature solution-processing method for the intercalation of Cs2CO3 into NiO, resulting in bipolar charge-carrier extraction capability for inverted (p–i–n) and conventional planar (n–i–p) PSCs. In comparison with the corresponding device featuring an HTL of NiO alone, the Cs2CO3-intercalated NiO layer exhibited enhanced electron extraction without sacrificing its hole extraction capability. This new material for bipolar charge-carrier extraction has the potential to serve as an inexpensive, scalable, and environmentally stable interconnection layer for emerging flexible tandem photovoltaic devices.

We report the first known example of a subwavelength plasmonic upconverting nanolaser with a low threshold. This perovskite-based plasmonic upconverting nanolaser features a record-small mode volume and an ultralow lasing threshold. Besides, we observed temporal coherence of the emission, which is an important feature of lasing. To co-optimize the pump photon absorption and the upconverted photon emission rate, the lasing result was made possible based on plasmonic titanium nitride. Moreover, we also demonstrated a new concept of lasing from a quantum emitter utilizing an intense localized electromagnetic field. A continuous-wave lasing was observed from single perovskite (CsPbBr3) quantum dot in a gap-plasmon nanocavity with an ultralow threshold of 1.9 Wcm-2 at 120 K. In the end, we will discuss the outlook for perovskite plasmonic nanolasers as on-chip light sources for bio-imaging, optical communication applications.

In this work, we investigate the ultrafast charge carrier dynamics in the double-layered architecture mixed halide (DHA) perovskite photovoltaic devices by ultrafast pump-probe transient absorption spectroscopy (TAS). The measured TAS results show the perovskite solar cell consists of SnO2/(FAPbI3)1-x(MAPbBr3)x/HTAB has stronger transient absorbance with photoinduced bleaching at 750 nm and photoinduced absorption in the range of 550-700 nm. The lifetime of DHA perovskite observed from TAS is approximately 46 µs in conjunction with the electron injection discovered within the first 150 fs, indicating the charge carriers would be easily extracted. Besides, we measured a high power-conversion-efficiency of the DHA perovskite solar cell (PSC) of 21%. Hence, understanding the ultrafast charge carrier dynamics in PSC by pump-probe TAS provides detailed insights into the advanced working mechanism. The results open a door for the development of high-performance perovskite photovoltaics.

The optical sectioning images of volumetric biological sample was obtained by varifocal metalens with Moire effect in fluorescence microscopy system in conjunction with telecentricity and HiLo image processing method. The varifocal metalens is capable of changing the focal depth ranging from 10 mm to 125 mm by tuning the relative angle between its paired metasurfaces. The standard resolution target and fluorescent mircrosphere are imaged and analyzed; its lateral resolution and optical sectioning capability are 2.46 μm and 7.5 μm, respectively. Our study offers a demonstration, a solid foundation, for developing more compact optical microscopy systems based on metasurface optics.

The optical tweezer is one of the important techniques for contactless manipulation in biological research to control the motion of tiny objects. For three-dimensional (3D) optical manipulation, shaped light beams have been widely used. Typically, spatial light modulators are used for shaping light fields. However, they suffer from bulky size, narrow operational bandwidth, and limitations of incident polarization states. Here, a cubic-phase dielectric metasurface, composed of GaN circular nanopillars, is designed and fabricated to generate a polarization-independent vertically accelerated two-dimensional (2D) Airy beam in the visible region. The distinctive propagation characteristics of a vertically accelerated 2D Airy beam, including non-diffraction, self-acceleration, and self-healing, are experimentally demonstrated. An optical manipulation system equipped with a cubic-phase metasurface is designed to perform 3D manipulation of microscale particles. Due to the high-intensity gradients and the reciprocal propagation trajectory of Airy beams, particles can be laterally shifted and guided along the axial direction. In addition, the performance of optical trapping is quantitatively evaluated by experimentally measured trapping stiffness. Our metasurface has great potential to shape light for compact systems in the field of physics and biological applications.

We design a novel phase real-time microscope camera (PhaseRMiC) for live cell phase imaging. PhaseRMiC has a simple and cost-effective configuration only consisting of a beam splitter and a board-level camera with two CMOS imaging chips. Moreover, integrated with 3-D printed structures, PhaseRMiC has a compact size of 136×91×60 mm3, comparable to many commercial microscope cameras, and can be directly connected to the microscope side port. Additionally, PhaseRMiC can be well adopted in real-time phase imaging proved with satisfied accuracy, good stability and large field of view. Considering its compact and cost-effective device design as well as real-time phase imaging capability, PhaseRMiC is a preferred solution for live cell imaging.

Liquid crystal (LC) cells that are coated with metamaterials are fabricated in this work. The LC directors in the cells are aligned by rubbed polyimide layers, and make angles θ of 0°, 45°, and 90° with respect to the gaps of the split-ring resonators (SRRs) of the metamaterials. Experimental results display that the resonance frequencies of the metamaterials in these cells increase with an increase in θ, and the cells have a maximum frequency shifting region of 18 GHz. Simulated results reveal that the increase in the resonance frequencies arises from the birefringence of the LC, and the LC has a birefringence of 0.15 in the terahertz region. The resonance frequencies of the metamaterials are shifted by the rubbing directions of the polyimide layers, so the LC cells coated with the metamaterials are passively tunable terahertz filters. The passively tunable terahertz filters exhibit promising applications on terahertz communication, terahertz sensing, and terahertz imaging.

Perfect absorbers (PAs) at near infrared allow various applications such as biosensors, nonlinear optics, color filters, thermal emitters and so on. These PAs, enabled by plasmonic resonance, are typically powerful and compact, but confront inherent challenges of narrow bandwidth, polarization dependence, and limited incident angles as well as requires using expensive lithographic process, which limit their practical applications and mass production. In this work, we demonstrate a non-resonant PA that is comprised of six continuous layers of magnesium fluoride (MgF2) and chromium (Cr) in turns. Our device absorbs more than 90% of light in a broad range of 900-1900 nm. In addition, such a planar design is lithography-free, certainly independent with polarization, and presents a further advantage of wide incidence up to 70°. The measured performance of our optimized PA agrees well with analytical calculations of transfer matrix method (TMM) and numerical simulations of finite element method, and can be readily implemented for practical applications.

Hybrid lead halide perovskites continue to attract interest for use in optoelectronic devices such as solar cells and light-emitting diodes. Although challenging, the replacement of toxic lead in these systems is an active field of research. Recently, the use of trivalent metal cations (Bi3+ and Sb3+) that form defect perovskites A3B2X9 has received great attention for the development of solar cells, but their light-emissive properties have not previously been studied. Herein, an all-inorganic antimony-based two-dimensional perovskite, Cs3Sb2I9, was synthesized using the solution process. Vapor-anion-exchange method was employed to change the structural composition from Cs3Sb2I9 to Cs3Sb2Br9 or Cs3Sb2Cl9 by treating CsI/SbI3 spin-coated films with SbBr3 or SbCl3, respectively. This novel method facilitates the fabrication of Cs3Sb2Br9 or Cs3Sb2Cl9 through solution processing without the need of using poorly soluble precursors (e.g., CsCl and CsBr). We go on to demonstrate electroluminescence from a device employing Cs3Sb2I9 emitter sandwiched between ITO/PEDOT:PSS and TPBi/LiF/Al as the hole and electron injection electrodes, respectively. A visible-infrared radiance of 0.012 W·Sr-1·m-2 was measured at 6 V when Cs3Sb2I9 was the active emitter layer. These proof-of-principle devices suggest a viable path toward low-dimensional, lead-free A3B2X9 perovskite optoelectronics.

In the present work, we report our recent efforts to improve the homogeneity of MgO buffer layers and superconducting YBa 2 Cu 3 O 7-δ coated tapes prepared by ion-beam-assisted deposition and metalorganic solution deposition (MOD), respectively. Based on previous research results involving fluorine, a reduced atmospheric pressure is used for the MOD technique to improve the in-plane texture and suppress microcracks in the film, and then more than 500 m of MOD-coated superconducting tape is manufactured, exhibiting an excellent biaxial texture and superconducting performance. The full width at half maximum values for both in-plane and out-of-plane textured films are as low as 3° based on X-ray diffraction (XRD) measurements. The superconducting current-carrying capacities for 12-mm tapes are approximately 450-520 and 450-500 A for the 100-m level and 500-m level (77 K, self-field), respectively. The current-carrying capacities were measured by both reel-to-reel transport and an inductive system, and the results demonstrated that the cost-effective MOD technique is very promising for long-length high-quality coated conductors.

In the current study, an analytical predictive model on residual stress after ultrasonic vibration–assisted milling is proposed in an effort to provide an accurate and reliable reference. Three types of tool-workpiece separation criteria are checked based on the tool center instantaneous position and velocity. Type I criterion examines the instantaneous velocity of tool tip under combined effects of feed movement and vibration. Type II criterion examines the position of tool center. Type III criterion describes the smaller chip size due to the overlaps between current and previous tool paths as a result of vibration. If none of these criterions is satisfied, the mechanical and thermal stresses are nonzero. The residual stress is then predicted through the calculation of stress distribution in loading process, incremental stress change considering kinematic hardening in plasticity, and the elastic stress release during relaxation process. The proposed predictive residual stress model in ultrasonic vibration–assisted milling is validated through comparison with experimental measurements on AISI 316L alloy. The proposed predictive model is able to match the measured residual stress with high accuracy of 6.4% average error and 23.6% maximum error among all cases. In addition, a sensitivity analysis is conducted. Higher axial depth of milling results in less compressive residual stress. Moreover, both higher ultrasonic vibration amplitude and higher spindle rotation frequency result in more compressive residual stress for AISI 316L alloy.

Polyvinyl chloride (PVC) films containing the mercaptan methyltin (S), zinc stearate (Z) and dipentaerythritol (D) additives were prepared. The thermal degradation kinetics of the films were investigated by nonisothermal thermogravimetry and TG–FTIR techniques. Using the nonmodel method and the Kissinger, the Friedman, the Kissinger–Akahira–Sunose and the Flynn–Wall–Ozawa methods, the average apparent activation energies of the PVC–SZD films in the first and second thermal decomposition stages obtained were 127.5 and 261.6 kJ mol−1, respectively. Compared with the experimental master plot by the generalized master plot, the experimental and theoretical master plots on the master plot of θ/θ0.5 versus α show that the thermal degradation of PVC-SZD film conforms to the chemical reaction F1.5 mechanism model. TG–FTIR analysis showed that the infrared vibration peaks ordered from strong to weak after adding SZD components were: νCO2 (638 °C) > ν(–COOR) (275 °C) > νHCl (299 °C). The thermal degradation of the film did not show hydroxyl or moisture formation compared to the blank. The removal of carboxyl groups of plasticizer dioctyl terephthalate (DOTP) in PVC was significantly inhibited, and the CO2 gas released by thermal degradation was reduced by 85.2%. This suggests that SZD has a strong interaction with the ester groups in DOTP, and there is the possibility of generating a more stable carboxyl group-containing metal complex, which creates favorable conditions for the recovery of DOTP. When the heating rates were 2.5, 5.0, 10 and 20 °C min−1, the lowest temperatures at which the conversions reached 5 and 10% were 226.1 °C and 239.1 °C, respectively.

A series of metal decorated hydrogenated TiO2 nanofibers (metal-H:TiO2 NFs) are synthesized successfully in this study. It is synthesized by the hydrothermal approach and combined with wet impregnation method in thermal hydrogen reduction. Nine types of metal nanoparticles, Ag, Co, Cr, Cu, Fe, Ni, Pd, Pt and Y, were used to decorate on the surface of H:TiO2 to enhance the photocatalytic activity. The photocatalytic performance of various metal-H:TiO2 NFs was estimated by the photodegradation of organic dyes. Ag-H:TiO2 NFs gives the fastest decoloration rate of brilliant green among others. Moreover, the evolution rate of H2 over Pd-H:TiO2 NFs under UV-A and UV-B illumination is 17,000 μmol/g·h and 25,600 μmol/g·h, respectively, which corresponding to photoefficiency values of ∼7.54% and ∼11.35%. The metal-H:TiO2 NFs developed in this study can be a facile and environmentally friendly way for searching the high-performance photocatalysts in the field of environmental and energy issue.

Three-dimensional Al4C3 nanowires have been synthesized by thermal evaporation process using CaO as an auxiliary agent. Morphologies, chemical composition and crystal structure of Al4C3 nanowires were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM) and x-ray diffractometer(XRD). The process yields a large fraction of long round-comb like Al4C3 nanowires of 300–500 nm in diameter. High-resolution transmission electron microscopy(HRTEM) shows that the Al4C3 nanowires are single crystals and the growth direction of nanowire trunk is [0001] axis of Al4C3 crystal. There are many Al4C3 nanorod branches of 500–1000 nm length on the nanowire trunk. The liquid reaction products of CaO and Al2O3 have contributed to the growth of round-comb like Al4C3 nanowires. A round-comb like growth model based on the vapor-liquid-solid (V-L-S) growth mechanism is proposed to explain the growth of Al4C3 nanowires, which reveals that the reason for this shape is that the liquid products of CaO and Al2O3 are dispersed in the nanowire trunk.

An analytical predictive model for residual stress in laser-assisted milling considering material recrystallization caused by laser preheating is proposed. The laser preheating temperature field is predicted by treating the laser beam as a heat source on top surface following Gaussian distribution. Heat convection between top surface and the environment is factored into account. Isothermal boundary conditions are assumed for the area of interest with conduction within the material. Next, the milling configuration is treated as orthogonal cutting at each instance. All process parameters including cutting depth, cutting speed, and tool geometry are therefore transferred. The recrystallization effect and thus the grain growth are considered through calibrated models describing the dependency of strain rate, strain, and temperature on dynamic recrystallization process for specific alloys using exponent functions. The residual stress is then predicted through the calculation of elastic stress distribution in loading process, actual stress with kinematic hardening, and the stress change during relaxation. The proposed model is validated through experimental measurements on the laser-assisted milling of Si3N4 and Ti-6Al-4V. The predictive model matches the trends of experimental measurements with agreement to an average error less than 30% in all cases. The proposed analytical model is valuable for providing a fast, credible, and physics-based method for the prediction of residual stress in laser-assisted milling of various materials.

Effective conversion of solar energy into chemical energy by visible light represents a potential strategy for sustainable development. Among which, photocatalytic hydrogen evolution reaction (HER) with a relatively small activation energy (1.23 eV, around 1000 nm light irradiation) is especially attractive. In this work, well-distributed platinum nanoparticles (Pt-NPs) with a width of about 3 nm have been successfully immobilized into the confined coordination interspaces of 3.7 nm diameter, which are facilitated by early transition metal Hf(IV)-based clusters of a self-sensitized palladium porphyrin metal–organic framework. Under visible light irradiation, the resultant Pt@Pd-PCN-222(Hf) (which is also denoted as Pt@Pd-PMOF-2(Hf)) displays superb photocatalytic activity, achieving an unprecedented maximum H2 evolution rate of 22 674 μmol g−1 h−1 with a turn-over number (TON) of 4131.2 in 32 h and the highest turn-over frequency (TOF) of 482.5 h−1 based on Pt-NPs. This photocatalyst can be recycled and reused for three successive runs without significant loss of catalytic activity. This effective strategy takes advantage of the synergetic effect between Pd-porphyrin photosensitizers and Pt-NP co-catalysts confined within nanoscale coordination interspaces incorporating hydrophilic Hf(IV)-oxo clusters.

Tuning the emissive color changes of lanthanide (Ln) complexes is an important and appealing project for promoting the applications of Ln-complexes. A solvothermal reaction of 4-cyano-3-methylbenzoic acid (HL) and Ln(NO3)3·6H2O affords three isostructural Ln-complexes [Eu(L)3(H2O)2]n (1-Ln) (Ln = Eu, Gd and Tb) with one-dimensional chain structures. 1-Eu and 1-Tb show bright red and green emissions with absolute quantum yields of 3.06% and 11.96%, respectively, and the energy transfer was analyzed in detail through combined calculations. Interestingly, a series of heterometallic doped 1-TbxEu1-x coordination polymers were also obtained by mixing different ratios of Eu3+ and Tb3+ ions, which possess continuous luminescent color changes from green to yellow, orange and red. In addition, 1-Eu exhibits high quenching efficiency and low detection limit (∼10-4 M) for the simultaneous sensing of MnO4-, CrO42- and Cr2O72- ions in water.

Sodium ion batteries are in great need of electrode materials with high specificity and rate capability being developed. The sluggish reaction kinetics of SnO2-based materials has impeded their applications as anodes of SIBs. Designing electrode materials with high pseudocapacitive contribution can increase the near-surface faradaic reaction, which helps to improve their kinetics and achieve high rate capability. Here, we designed a high-pseudocapacitance sodium storage anode SnO2/N-rGO by downsizing the particle size of SnO2 and constructing an N-doped graphene wrapped structure. The ultrafine structure of SnO2 ensures the high faradaic near-surface reaction, while the N-doped graphene matrix guarantees the superior electron and Na+ diffusion. Meanwhile, the wrapped N-doped graphene acts as a buffer layer to alleviate the volumetric changes of the active SnO2. The obtained ultrafine SnO2/N-graphene composite exhibits a high capacity of 607.6 mA h g-1 at 50 mA g-1 with an impressive rate capability (261.8 mA h g-1 at 2 A g-1) in Na+ half-cells. Furthermore, a good performance with a capacity of 133.3 mA h g-1 at 2.4 A g-1 in Na+ full-cells can also be achieved, which makes it a promising anode material for SIBs.