A series of ${\left\hbox[ {{{\left\hbox( {{\rm{SnSe}}} \right\hbox)}_{1 \hbox+ \delta }}} \right\hbox]_m}{\left\hbox[ {{\rm{TiS}}{{\rm{e}}_2}} \right\hbox]_2}$ heterostructure thin films built up from repeating units of m bilayers of SnSe and two layers of TiSe2 were synthesized from designed precursors. The electronic structure of the films was investigated using X-ray photoelectron spectroscopy for samples with m = 1, 2, 3, and 7 and compared to binary samples of TiSe2 and SnSe. The observed binding energies of core levels and valence bands of the heterostructures are largely independent of m. For the SnSe layers, we can observe a rigid band shift in the heterostructures compared to the binary, which can be explained by electron transfer from SnSe to TiSe2. The electronic structure of the TiSe2 layers shows a more complicated behavior, as a small shift can be observed in the valence band and Se3d spectra, but the Ti2p core level remains at a constant energy. Complementary UV photoemission spectroscopy measurements confirm a charge transfer mechanism where the SnSe layers donate electrons into empty Ti3d states at the Fermi energy.

Raman spectroscopy is a fundamental tool for the characterization of two-dimensional materials. It provides insights into the electronic and vibrational properties of these materials and is particularly rich in features when the incident laser energy approaches the electronic energy transition of the material. Among these features, the double resonance Raman process provides important information on the electron, phonon, and electron–phonon properties. It was on the study of carbon-related materials that the double resonance bands sparkled showing their potential and, since then, have been deeply searched in the study of novel 2D materials. Here, the authors review the double resonance Raman process in 2D materials focusing on graphene and semiconducting MoS2 highlighting the origin of the bands mediated by the two-phonon and phonon–defect processes. The authors discuss the observed properties of the double resonance bands and compare the processes for graphene and MoS2 to find guiding principles for the appearance of double resonance bands. The authors also discuss the new findings of the intervalley scattering process in transition metal dichalcogenides. A brief discussion of the defect-induced bands in both materials is also presented.

Heteroatom-doped carbon plays a vital role in the field of energy storage and conversion, and the synthesis of them has intimate relation with doping pathways. In this work, a facile two-step doping pathway, i.e., hydrothermal method followed by thermal annealing process, was employed to prepare annealed three-dimensional N,S-codoped graphene framework (3D A-NSG). The morphology, structure, composition, and related electrochemical performance were all studied. The results showed that A-NSG possessed typical 3D thin nanosheets, much increased specific surface area and structural defects, strengthened conductivity, and optimized N and S configurations (especially for dominated pyridinic N as well as graphitic N and –C–S–C–). As a result, A-NSG presented much better capacitance and oxygen reduction reaction performance than the counterparts. Apparently, our work offers a good guidance on the synthesis of advanced heteroatom-doped carbon materials by adjusting the doping strategy.

Noble metals combined with some oxides have synergetic contributions to surface-enhanced Raman scattering (SERS). In this work, a new method of de-oxide was proposed to prepare nanoporous metal based composites. Nanoporous Ag decorated with CeO2 nanoparticles was successfully prepared by decomposing Ag/CeO2/ZnO precursors in a 10 wt% NaOH aqueous solution. During the process of de-oxide, ZnO in the precursors could be removed completely and the nanoporous Ag/CeO2 nanocomposites with rough ligament surfaces were formed. The results indicated that the contents of CeO2 had significant influences on the microstructure and SERS performance of the prepared Ag/CeO2 materials. Using R6G and L-phenylalanine as probe molecules, the nanoporous Ag/CeO2(0.5%) substrates demonstrated a high enhancement factor of 1.2 × 108. The improved SERS performances were mainly attributed to the strong coupling effects between Ag ligament and CeO2 nanoparticle. This work would like to be interesting for the design of nanoporous composites for the application in the fields of SERS technology.

In this work, graphene and graphene oxide were synthesized by the modified Hummers method. In order to use graphene in dye-sensitized solar cell (DSSC), TiO2–graphene was prepared by a simple chemical method and used in the DSSC photoanode at different concentrations of graphene to investigate DSSC performance. Utilizing the FE-SEM images, it was observed that accumulation of TiO2 nanoparticles disappeared and a different distribution of nanoparticles was formed on the graphene sheet. Moreover, the UV-vis spectra showed that TiO2–graphene nanocomposites can absorb a wide range of light in comparison with pure TiO2. Structural characterization of TiO2–graphene nanocomposites is confirmed by the FT-IR and Raman analysis. The results have shown that in the presence of graphene, the DSSC performance significantly improved by reducing the recombination. In addition, it has been shown that excess graphene concentration is not proper for DSSC performance. The best result for TiO2–graphene nanocomposite was obtained when the concentration of 1.5% graphene was applied.

A novel and highly efficient Ag3VO4/C3N4/reduced TiO2 microsphere composite was obtained through a hydrothermal and depositional process. The microstructure, individual components with different proportions, and optical properties of the ternary nanocomposites were intensively studied. The prepared ternary composites exhibited superior photocatalytic performance of degradation of methylene blue compared with single component and S1 (C3N4/reduced TiO2) binary composites, demonstrating that the introduction of Ag3VO4 into g-C3N4/r-TiO2 can effectively improve the photocatalytic activity. Recycling experiments confirmed that the nanocomposites exhibited superior cycle performance. The enhanced capability could be attributed to a synergetic effect including the formation of heterojunction, large surface area, improved light absorption, matched energy band structure, and the improved separation efficiency of photogenerated charges coming from dual Z-scheme structure. Particularly, the introduction of Ag3VO4 makes the dual Z-scheme charge transfer pathway completed with improved separation efficiency and stronger redox ability of photogenerated electrons and holes. The work provides a promising method to develop a new dual Z-scheme photocatalytic system to remove environmental pollutant.

Surface modification with poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) is an effective method for improving hemocompatibility. Peptide GREDVY immobilized on Ti is of great benefit to endothelialization. Micropattern of PMPC and GREDVY can regulate cells distribution, behaviors, and nitric oxide (NO) release. Copper can be used as catalytic to release NO from a donor in vitro, which can inhibit platelets adhesion, activation, and aggregation. The Ti-PDA(Cu)-M/R(P) micropattern was fabricated with PMMPC-HD {PMMPC [monomer contain MPC and methacrylic acid (MA)] was cross-linked with hexamethylene diamine} and peptide Gly-Arg-Glu-Asp-Val-Tyr (GREDVY) using PDMS stamp, and it was characterized by SEM, FTIR, and XPS. The results demonstrated that the PMPC and peptide GREDVY were immobilized onto polydopamine successfully. Simultaneously, the copper existed in polydopamine was confirmed by XPS. The rate of NO release in vitro catalyzed by copper ions was 1.5–5.3 × 10−10 mol/(cm2 min). It will be beneficial to inhibiting platelets adhesion and proliferation of ECs.

Novel microencapsulated n-octadecane with natural silk fibroin (SF) shell attached with silver nanoparticles (AgNPs) on its surface was synthesized in oil-in-water emulsion via a self-assembly method. No additional reductant was used in the in situ preparation of AgNPs due to the inherent reduction property of tyrosine (Tyr) residues in SF. The microstructures and particle sizes of the resultant microcapsules were investigated by using a scanning electron microscope (SEM) and a laser scattering particle size distribution analyzer. The resulting microcapsules exhibited a regular spherical morphology with a 4–5 μm narrow diameter distribution range. And the AgNPs attached to the surface exhibited an even distribution. According to the analytical results of DSC, TGA, and infrared system, the SF-AgNPs microcapsule presents enhanced thermal stability and obvious thermal regulation properties. In addition, it was found that the SF-AgNP microcapsule also exhibited a good antibacterial activity against both Gram-positive bacteria (Staphylococcus aureus), and Gram-negative bacteria (Escherichia coli). The SF-AgNPs microcapsule synthesized in this study could be a potential candidate for thermal regulation and healthcare applications.

Two wide band gap conjugated polymers, namely PBDT-TT25 and PBDT-TT36, derived from (4,8-bis(4,5-dioctyl-thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane) with 2,5-dibromothieno[3,2-b]thiophene (TT25) or 3,6-dibromothieno[3,2-b]thiophene (TT36), have been synthesized by simply altering the linker positions of thieno[3,2-b]thiophene unit. The impact of linker positions on the energy levels, aggregation, active layer morphology, and optical and photovoltaic properties was evaluated systemically. We found that the absorption was greatly broadened, and the highest occupied molecular orbital (HOMO) energy level was elevated as the result of the significantly reduced twist angle on the polymer backbone when the linker positions changed from 3,6-isomer to 2,5-isomer. Therefore, the optimal inverted polymer solar cells exhibited a 1.87 times enhancement in power conversion efficiencies (PCE), which was mainly ascribed to the higher short circuit current densities (JSC) and fill factor (FF) of the devices mainly benefited from the widened, stronger absorption, higher hole mobility, and more ordered structure.

La3+-doped BaSnO3 microtubes (La3+–BaSnO3) have been synthesized by electrospinning method, and the influence of La3+ content on the sensing properties of BaSnO3 for detection of formaldehyde vapor has been investigated. The as-prepared materials have been characterized using XRD, SEM, DSC, XPS, and UV-Vis. The La3+–BaSnO3 sample doped with 4 wt% La exhibited a response as high as 220 to formaldehyde vapor (1000 ppm concentration) along with a very low detection limit of 0.1 ppm at 270 °C, whereas at 140 °C, it exhibited a response of 80 and detection limit of 1 ppm. In addition, the sensor showed excellent selectivity of 57 to formaldehyde at 140 °C when compared with other vapors. Further, the sensor also showed good repeatability and stability over a long period of time suggesting its strong potential as a commercial formaldehyde sensor.

A novel high-power impulse plasma source (HiPIPS) technology that combines atmospheric pressure plasma jets with high-power pulsed direct current generators is described. Pulsed power is applied in microsecond pulses (20 µs) at low duty cycle (10%) and low frequency (0.5 kHz) leading to high peak power densities (10–75 kW) and high peak currents (100–250 A) while maintaining low average power (<40 W) and low processing temperatures (<50 °C). These conditions result in the generation of a highly dense plasma discharge (ne = 6.23 × 1016 cm−3) for surface modification and deposition of coatings. Using HiPIPS, Ar-initiated metallic Ti, CoCr, or Ti–6Al–4V plasma was generated, and the plasma properties were characterized by measuring current–voltage characteristics, electron densities (Langmuir probe), and optical emission spectra. HiPIPS CoCr and Ti–6Al–4V coatings were deposited for proof of concept of the technique. The resulting coatings were examined with scanning electron microscopy, energy-dispersive X-ray spectroscopy, and nanoindentation.

Nanoporous copper (NP-Cu), as a sacrificial support, was used for the synthesis of bimodal nanoporous palladium–copper (BNP-PdCu) for oxygen reduction reaction (ORR) electrodes in fuel cells. The catalytic performance of BNP-PdCu in ORR per electrochemical surface area was enhanced by the dissolution and removal of supporting NP-Cu, which indicates that the intrinsic catalytic properties of palladium are improved by the proposed synthesis strategy including galvanic replacement of copper with palladium, following copper dissolution. Cu remained on Pd surfaces even after dissolution of Cu. Additionally, significant local lattice contraction was observed at the ligament surface. First-principles calculations on the adsorbing oxygen species on Pd show that both lattice contraction and alloying with copper increase the binding energies of oxygen species to the Pd surface. The high ORR activity of the present BNP-PdCu is suggested to be mainly due to the Cu-ligand effect.

Bimetallic nanoparticles (NPs) have attracted a great deal of attention due to the synergistic interaction between metal components. In this work, the thermal process in which the reducing agent is not expensive or hazardous as those in traditional methods was employed to prepare alloy Ag–Cu NPs. The molar ratio between Ag and Cu was varied from 1:9 to 9:1. Nearly monodisperse NPs with alloy structure were characterized by X-ray diffraction and high-resolution transmission electron microscopy with energy dispersive spectroscopy In comparison with monometallic Ag and Cu NPs, the alloyed Ag–Cu NPs showed better monodispersity, especially when the ratio between Ag and Cu was 1:1. Moreover, the alloyed Ag–Cu NPs exhibited enhanced resistance to electromigration and oxidation, the respective problem of pure Ag and Cu. The alloyed Ag–Cu NPs also exhibited improved properties than a mixture of Ag–Cu NPs. This study should serve as the foundation for exploring high performance alloyed bimetallic NPs.

Refinement and homogenization of primary Si particles in hypereutectic Al–Si alloys is an effective route to enhance the tensile strength and wear resistance and satisfy the industrial requirements for a wide range of applications. Herein, two kinds of semisolid hypereutectic Al–Si alloys are synthesized by using a rotating-rod-induced nucleation technology. The influence of different cooling conditions and shear rates on the apparent viscosity of molten melt of slurry are examined by self-made high-precision and high-temperature apparent viscosity test equipment. The correlation between the shear rate and the uniformity of hard phases has been investigated from the obtained results, fitting curves, and optical microscope. With the increase in the shear rate, the particles tend to become rounder and the apparent viscosity becomes lower. The enhanced shape factor resulted in more rounded grains, which further reduced the apparent viscosity. During the same cooling time, the higher cooling rate resulted in higher solid fraction, generating higher apparent viscosity. The present study provides unique insight into the filling behavior of semisolid hypereutectic Al–Si alloys and serves as a baseline for future work.

The hot compression behavior of as-extruded AZ31 magnesium alloy was investigated to study the effect of compression temperature and strain on microstructure evolution, grain orientation, and texture evolution. The thermal compression tests of AZ31 Mg alloy were carried out on the Gleeble-3800 simulation device: With constant strain, the temperatures were 250, 300, 400, and 500 °C, respectively; at constant temperature, the strains were 0.2, 0.4, 0.6, and 0.8, respectively. After observation and analysis of compressed samples, it is found that with 0.65 strain and 0.05 s−1 strain rate, grains were equiaxed, well refined, and distributed uniformly at 400 °C. At this temperature, new orientation between {0001} and $\left{\rm\char123} {12\bar{1}0} {\rm\char125} \right$ or $\left{\rm\char123} {01\bar{1}0} {\rm\char125} \right$ appeared in grains; new texture components close to $\left{\rm\char123} {\bar{1}\bar{1}22} {\rm\char125} \right$ and $\left{\rm\char123} {1\bar{2}12} {\rm\char125} \right$ pyramidal textures were formed, but whole texture strength was weakened and anisotropy of the sample was reduced. With the increase of strain, grains became smaller and volume fraction of DRX grain became higher; the original basal texture was replaced by prismatic textures; after 0.4 strain, the increase of strain did not change the texture component, but only the pole density.

A homogeneous structured CoCrNi medium-entropy alloy was synthesized by gas atomization and spark plasma sintering (SPS). The mechanical properties, corrosion resistance, and magnetic properties were reported in this study. The as-atomized CoCrNi MEA powder, with a spherical morphology in shape and a mean particle diameter of 61 μm, consisted of a single face-centered cubic (FCC) phase with homogeneous distributions of Co, Cr, and Ni elements. Also, the cross-sectional microstructure of powder particles gradually transformed from fully cellular structure into equiaxed-type structure with increasing particle size. After being sintered by SPS, the CoCrNi MEA consisted of a single FCC phase with a mean grain size of 20.8 μm. Meanwhile, the CoCrNi MEA can capable of offering an ultimate tensile strength of 799 MPa, yield strength of 352 MPa, elongation of 53.6%, and hardness of 195.3 HV. In addition, this MEA showed superior corrosion resistance to that of 304 SS (stainless steel) in both 0.5 mol/L HCl and 1 mol/L NaOH solutions. The magnetization loop indicated that this MEA has good soft magnetic properties.

Noble metal (Ag, Au) nanoparticles (NPs) deposited on the surface of three-dimensional (3D) materials are promising 3D surface-enhanced Raman spectroscopy (SERS) substrates. In this work, the authors reported the preparation of 3D wax/silica/Ag(Au) colloidosomes by sulfonic acid group–terminated silica spheres (SiO2–SO3H) combined with a Pickering emulsion technique, as well as seed-mediated growth method of noble metal NPs. The presence of –SO3H group on the silica spheres not only improves significantly the quality of wax/silica colloidosomes (forming perfect silica shell around wax droplet) but also can adsorb metal precursor ions via electrostatic attraction for further growth of metal NPs. The size and coverage of Ag(Au) NPs on wax/silica droplets can be facilely tuned, and relevant wax/silica/Ag(Au) colloidosomes and silica/Ag(Au) Janus particles are obtained via this strategy. The obtained wax/silica/Ag colloidosomes as 3D SERS substrates exhibited excellent SERS enhancement ability and detection limit of 4-aminothiophenol reached 10−9 M.