Nano

A novel heterojunction photocatalyst consisting of three-dimensional (3D) flower-like MgAl LDH and acidified g-C₃N₄ (CN-H) was first developed by a simple facile coating method. The obtained MgAl LDH/CN-H samples were thoroughly characterized by powder X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and Brunauer–Emmett–Teller (BET) analyzer. The detailed results demonstrated that g-C₃N₄ could transform from a generally two-dimensional layered structure into special cavity-like structure after acid treatment. CN-H increased specific surface to expose more active reaction sites in comparison to pristine g-C₃N₄. MgAl LDH and CN-H with matched band gaps were tightly bonded to form heterojunction structure by strong electrostatic intercalation. The combination could obviously boost the separation of photogenerated carriers. The as-prepared MgAl LDH/CN-H exhibited high photocatalytic performance in the degrading on typical antibiotic tetracycline hydrochloride (TC$\cdot$HCl), of which degradation rate was 6.5 and even 22 times higher than that of MgAl LDH and pristine g-C₃N₄, respectively. The synthesis of MgAl LDH/CN-H heterojunction photocatalyst could have some positive suggestions for the rational construction of new photocatalysts and also has great application prospect in the degradation of environmental pollutants.

Potassium chloride (KCl) nanoparticles were synthesized by ball milling technique with different milling time. The effect of milling time on structural and optical properties was investigated. The structural properties of the purchased samples are characterized by Raman spectroscopy, scanning electron microscope and X-ray diffraction techniques. The Raman spectroscopy of the KCl hints at an excellent alloying behavior of those compounds and a preferred crystal structure for certain composition. The optical band is calculated by analyzing the spectral behavior of the absorption coefficient in the absorption region which revealed direct transitions. The value optical band increases (4.02–5.11eV) with increasing milling time (0–15h) due to quantum confinement after the ball milling process. The refractive and absorption indices were calculated for all samples. The model of Wemple–DiDomenico was used to calculate the dispersion parameters. The nonlinear susceptibility of the third order and the nonlinear refractive index were calculated by linear optical parameters using the generalized Miller rule.

To obtain solid-state photoluminescent core–shell-structured carbon dots@silica (C-dots@SiO₂) nanocomposites, the C-dots were synthesized by microwave irradiation and were dispersed in SiO₂ through sol–gel technique. Then, the excellent fluorescent property with excitation-independent feature and the core–shell structure of C-dots@SiO₂ nanocomposites were successfully characterized through the fluorescence spectroscopy, ultraviolet–visible absorption spectroscopy (UV-Vis), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The as-prepared C-dots@SiO₂ powder was mixed with reduced iron powder and then applied to latent fingermark detection. The latent fingermarks on several surfaces labeled with C-dots@SiO₂ fingermark powders emitted blue fluorescence under 365nm UV light and exhibited high contrast between the background and the ridges. Additionally, the C-dots@SiO₂ fingermark powder as a fluorescent label for enhancing latent fingermarks demonstrated greater advantages as compared to the conventional fluorescent fingermark powder especially for latent fingermark deposited on porous surfaces.

The ability to control the shape, structure and faceting characteristics of bimetallic alloy nanocrystals (NCs) has been vital for designing a catalyst with excellent activity and durability in fuel cells. However, it has remained a significant challenge to synthesize platinum–copper (Pt–Cu) alloy NCs with controlled structure and exposed facets. Herein, Pt–Cu alloy NCs with different shapes, structures and facets were synthesized via a one-step direct chemical co-reduction method employing various glucose concentrations. The results showed that the prepared Pt–Cu alloy NCs exhibited very interesting facet-dependent electrocatalytic properties for ethylene glycol oxidation. In comparison with other prepared Pt–Cu alloy NCs and commercial Pt/C, Pt–Cu alloy NPs with (111)-dominant facets showed higher electrocatalytic activity and durability for ethylene glycol oxidation. Alloy NPs showing prominent electrocatalytic performance were attributed to the predominant (111) facets on NP surfaces serving as catalytic active sites, in addition to added Cu providing unique electronic and synergistic effects. The present work highlighted that these NPs with (111)-dominant facets were indeed promising candidates as electrocatalysts with excellent activity and superior durability.

We report a facile synthesis method on CuInSe₂ (CISe)-based quantum dots (QDs) by using tri-$n$-octylphosphine selenium (TOPSe) as selenide precursor, with assistance of oleylamine (OAm) and $n$-dodecanethiol (DDT). We demonstrate that the OAm and DDT jointly contribute to the formation of the low-temperature-decomposable metal-sulfide clusters, and promote the QD nucleation at relatively low temperature range of 180–200^∘C. Furthermore, to improve fluorescence property, Zn-doping and ZnSe coating are simultaneously carried out. The obtained deep-red ZnCISe/ZnSe QDs possess higher quantum yield of 65% at wavelength of 670nm, which is in the best performance range ever reported. Then, we investigate the improvement mechanism, where the sufficient Zn replacement of In sites is the crucial factor. This modified core–shell structure provides two benefits, on the one hand, the enhancement on intrinsic defect-related recombination, and the other hand, the improved core–shell interface that reduces the nonradiative recombination.

The extinction spectral properties based on localized surface plasmon resonance (LSPR) of the concentric dual-ring nanodisk (CDRN) structure are investigated by discrete dipole approximation (DDA) and plasmon hybridization theory. The CDRN nanostructure shows flexible tunable multipole resonances in the near-infrared regime and the coupled resonance wavelengths depend on the structural parameters of the nanostructure, which has great potential in multichannel LSPR-based bio-sensing applications.

Hierarchical N-doped carbon nanotubes (NCTs) with controllable aspect ratios were developed for CO₂ adsorption. In this work, NCTs were synthesized by coating different amounts of 3-aminophenol/formaldehyde resin (APF) on the outer layer of silica nanotubes, carbonizing in N₂ at 700^∘C and removing the silica and Ni template by hydrofluoric acid etching. The obtained NCTs were activated by K₂CO₃. After activation, micropores on the activated N-doped carbon nanotubes (ANCTs) were enriched, the micro-surface area and pore volume of ANCT-1.0 reached 1195m²g${}^{-1}$ and 0.45cm³g${}^{-1}$, respectively, and the corresponding adsorption capacity increased by 50% (4.50mmolg${}^{-1}$ at 0^∘C and 1 bar). Moreover, ANCT-1.0 maintained a high stability throughout consecutive adsorption–desorption cycles. The advantages of hierarchical N-doped carbon nanotubes, including their meso–microporous structures, high geometric aspect ratio and good stability, make them valuable and promising materials to capture carbon dioxide.

This paper reports a surfactant-free synthesis of clean-surface dendritic Pd nanostructures. The key of this synthetic strategy was using ethanol as a reductant to directly reduce Pd(OH)₂. In terms of electrocatalytic methanol oxidation in alkaline media, the clean-surface and self-supported Pd nanostructures are beneficial to a high catalytic performance, including superior electrocatalytic activity and stability. The as-prepared dendritic Pd shows 2.57 and 4.39 times higher specific activity than palladium nanoparticles and a commercial Pd/C catalyst, respectively. Furthermore, we demonstrated that the clean-surface nanoparticles exhibit higher performance than that of the surfactant-capped Pd nanostructures for methanol electro-oxidation. Therefore, the dendritic Pd nanostructures are potential candidates as the efficient electrode material in fuel cells.

Carbon nanotubes (CNTs) were welded on the surface of thermoplastic polypropylene (PP) substrate by laser irradiation and then manganese dioxide (MnO₂) was deposited on the surface of CNTs by electrochemical method to prepare CNTs/MnO₂ flexible electrodes (L-CM). The microstructure and morphology of CNTs/MnO₂ composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The results showed that CNTs were welded on the surface of the substrate, adhering to each other to form a porous network structure. In addition, there were distinct small protrusions on the surface of CNTs, indicating that MnO₂ had been successfully deposited on the surface of CNTs. Cyclic voltammogram (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques were employed to investigate the electrochemical performance of the composites. Compared with CNTs/MnO₂ composite prepared via compaction (denoted as C-CM), L-CM composite prepared under the laser power of 0.75W (denoted as L-CM75) showed a larger capacitance of 214.6Fg${}^{-1}$ at the current density of 0.5Ag${}^{-1}$ and displayed excellent bendability, demonstrating capacitance retention of approximately 89.6% after 1000 bending cycles. The excellent performance of L-CM75 may be attributed to the fact that the CNTs welded on the substrate have formed an effective conductive network whose porous structure can facilitate easy access of electrolytes to the electrode, which results in enhancement of the electrochemical performance of L-CM75.

As the portable device hardware has been increasing at a noticeable rate, ultrathin flexible materials with the combination of high thermal conductivity and excellent electromagnetic interference (EMI) shielding performance are urgently needed. Here, we fabricated ethylene propylene diene monomer rubber with different loading graphene nanoplatelets (GnPs/EPDM) by a cost-efficient approach, which combines mixing, ultrasonication and compression. Further investigation demonstrates that the 8wt.% GnPs/EPDM with only 0.3mm in thickness shows excellent electrical conductivity (28.3S/m), thermal conductivity (0.79W/mK) and good mechanical properties. Besides, the 8wt.% GnPs/EPDM exhibits an EMI shielding effectiveness (SE) up to 33dB in the X-band (8.2–12.4GHz) and 35dB in the Ku-band (12.4–18GHz), superior to most of the reported rubber matrix. Additionally, the GnPs/EPDM shows excellent flexibility and stability with 95% and 94% retention of EMI SE even after repeated bending for 5000 times and corrosion (under 5% NaCl environment) for a week. Our flexible EMI shielding material will benefit the fast-growing next-generation commercial portable flexible electrons.

We prepared a series of Gd₂O₃:Yb,Er,Ca (3/1/$x$mol.%, $x$ represents the nominal concentration of Ca element including 0, 2, 3, 4, 5, 7, 10) upconversion nanoparticles (UCNPs) with regular morphology via a wet-chemical route. We observed a simultaneous enhancement of upconversion luminescence (UCL) emission of Gd₂O₃:Yb,Er after Ca${}^{2+}$ ions were doped. When the doping level of Ca${}^{2+}$ reaches its optimal concentrate at 5mol.%, the red and green emissions increased by 6.3 and 11 times, respectively. The potential application of Gd₂O₃:Yb,Er,Ca material as a noninvasion optical thermometry based on FIR technique was investigated. The sensing of temperature at both high and room temperatures was realized by choosing different parameters. The absolute temperature sensitivity ($S_a^{\prime }$) of Gd₂O₃:Yb,Er nanoparticles at 293K reached 0.0875K${}^{-1}$, whereas Gd₂O₃:Yb,Er, 5mol.%Ca was chosen as sensor of high temperature due to its considerable Sa of 0.0060K${}^{-1}$ at 573K. The resultant UCNPs provided a new way for sensitive thermal detection at various target temperatures.

Titanium dioxide (TiO₂) nanorods (NR) structure and Chlorine substitution is beneficial to the extraction and diffusion of electrons in perovskite solar cells (PSCs). In this work, different concentrations of PbCl₂ in perovskite are integrated with TiO₂ (NR) to fabricate PSCs. The total thickness of perovskite absorber layer and electron transport layer (ETL) is about 850nm, and the PSCs exhibit excellent performance. Scanning electron microscope (SEM) and X-ray diffraction (XRD) test reveal that moderate PbCl₂ additive improves the perovskite film morphology and crystal quality of perovskite films. Optimal perovskite films with high crystallinity and uniform surface were prepared by adding 3mol% PbCl₂ into perovskite precursor solution, the crystal boundary and defect states are greatly reduced, thus reducing the electrons and holes recombination. The power conversion efficiency (PCE) enhancement of the device with this optimal molar ratio of PbCl₂ is over 24% compared with the device without PbCl₂.

A covalent linkage between polyaniline (PANI) and Si nanoparticles in PANI-encapsulated Si nanocomposites was proposed and achieved by a facile and economical synthetic strategy, in which NH₂-grafted Si was first obtained via a chemical modification of Si surface and the polymerization of aniline initiated at NH₂ group surface was readily accomplished to get PANI shell. The characterizations suggested that NH₂ groups were successfully introduced onto Si surface and PANI-encapsulated Si nanocomposites with a core/shell structure were fabricated. Electrochemical tests showed that our proposed Si nanocomposites delivered a high initial specific capacity of 2135mAh/g and retained 848mAh/g after 100 charge/discharge cycles at a current density of 0.1A/g, which were superior than that of the normal PANI-encapsulated Si nanocomposites with the absence of chemical bonds in the interface. The enhanced electrochemical performance was ascribed to the surface chemical modification and the introduction of chemical bond in the interface. NH₂ group function of Si could improve the homogeneity of encapsulated PANI shell. Additionally, PANI was tightly anchored to Si nanoparticles via a covalent bond between silicon and PANI, which would greatly inhibit the separation of PANI from Si surface during the expansion/contraction of Si particles. Thus, the structural integrity was maintained. Besides, PANI layer with a unique structure promoted the transport of both electrons and lithium ions.

Deliberately engineering oxide composites on constructing and manipulating interactive structures particularly in surface layers was highly desirable for heterogeneous catalysis. Herein, upon the redox replacement reaction between Ce(IV) precursor (Ce(NO${}_3{)}_6^{2-})$ and Cu₂O nano-substrate, an attempt to directly engineer the surface structure of Cu-based substrate was performed by the Ce(IV)–Cu₂O etching-embedding process, then the obtained powders were thermo-treated to get a series of Ce–O–Cu catalysts with different Ce:Cu molar ratios for NH₃ selective catalytic reduction (NH₃-SCR) of NO. Characterized by ICP-OES, XRD, Raman, XPS, SEM, BET, H₂-TPR, NO- and NH₃-TPD measurements, it was demonstrated that the Cu–O–Ce catalysts were structured as CuO matrix with an interactive surface composed by co-present Cu(I)–Cu(II) and Ce(III)–Ce(IV) species, even the introduction of Ce was confined in a quite low loading range (0.83–2.3wt.%); such a surface exhibited the distinct synergistic effect with positively manipulated physical-chemistry properties such as active site distributions, redox features and surface reactivity compared to pure CuO and traditional Cu–Ce composite catalyst, leading to attractive catalytic performance such as $\ge 90$% NO conversion with $\ge 95$% N₂ selectivity and the two-fold TOF enhancement versus traditional catalysts, even SO₂ was present in reactant mixture on well-manipulated catalyst (Ce loading at 1.6wt.%) These results indicated that the etching-embedding strategy illuminated in this work could be referred as a feasible method to directly engineer and construct interactive oxide composite surface for advanced application as well as current efficient Ce–O–Cu catalytic interface for heterogeneous catalysis.