Nano

A cooperative assembly route has been developed, by which silver nanoparticles with controlled sizes are incorporated into the channels of ordered cubic mesoporous silica (KIT-6) with different pore sizes (4.3–6.4nm). The samples were characterized by XRD, TEM, FT-IR, UV-Vis and N₂ physisorption. The pore wall of mesoporous silica can efficiently confine the growth of silver nanoparticles within the channels and their average sizes decreased with the pore size reduction of KIT-6. Catalytic activities of the resultant Ag/KIT-6-$x$ ($x$ stands for hydrothermal temperature) composite for reducing harmful organic dye Rhodamine B (Rh B) by sodium borohydride (NaBH₄) were investigated. All the Ag/KIT-6 composite samples show great catalytic activities, among which Ag/KIT-6-80 with higher loading and smaller size of Ag nanoparticles exhibits higher catalytic activity than those of Ag/KIT-6-60 and Ag/KIT-6-100.

In this work, a synthesis method of residue-free PdPt nanodendrites on reduced graphene oxide (rGO) is reported. Using UV light as an energy trigger and methanol as the reducing agent, PdPt nanodendrites are synthesized with clean, residue-free surfaces (e.g., surfactant and polymer). In comparison with commercial Pd/C and Pt/C catalysts, the as-prepared PdPt nanodendrites on rGO have a large electrochemically active surface area, enhanced catalytic activity, high stability, and tolerance toward the ethanol oxidation reaction in alkaline media. Among the nanodendrite composites prepared, those containing a Pd:Pt ratio of 1:2 on rGO exhibit the best stability and durability, and their mass activity is 2.0 and 2.4 times greater than those of commercial Pt/C and Pd/C catalysts, respectively. This strategy presents an environmentally friendly way to fabricate other noble metal catalysts with improved catalytic activity and stability for use in direct alcohol fuel cells.

Zn${}^{2+}$-doped CTAB@BiOCl inorganic–organic composites were prepared by a co-precipitation method with different aging periods. The results show that the aging period has great influence on the structure, morphology and surface area of Zn${}^{2+}$-doped CTAB@BiOCl. The as-synthesized samples tend to form lamellar stacking structure with the increase of the aging time. In addition, the surface area and pore size distribution of samples decrease with the aging period from 0h to 48h and then increase from 48h to 96h. Besides, the content of CTAB in these composites increases along with the aging period from 0h to 3h and then decreases from 3h to 96h. Their photocatalytic performances were evaluated by the degradation of Reactive Red 3 (X3B) under UV light irradiation. It is found that the photocatalytic performance of composites increases with the prolonging of the aging time, and 100mg/L of X3B solution can be almost completely degraded within 16min by S${}_{96}$. Moreover, the possible formation mechanism has been proposed and discussed in detail. The work can provide a new sight for broadening the application of co-precipitation in the preparation of nanomaterials and for in-situ one-step synthesis of inorganic–organic composites.

The facile and ecofriendly method for the synthesis of a suitable colloidal nanocrystal ink plays an important role in the field of solar cells. Here, we describe our recent efforts toward this direction by a simple one-pot colloidal method to engineer CuInSe₂ (CISe) nanocrystals with cubic zincblende (ZB) structure. The suitable band gap value and obvious photoresponse of the as-synthesized CISe nanocrystals indicate their potential application in the field of thin film solar cells. In addition, a possible crystal growth mechanism has been suggested for the formation of ZB CISe.

Ionic liquid modified carbon dots (CDs-IL) were successfully synthesized by one-pot pyrolysis. The tribological properties of CDs-IL as a kind of water-based lubricant additive were investigated under four-ball mode. The experimental results demonstrated that the added CDs-IL not only increased load-carrying capacity of base liquid but also displayed remarkable friction-reducing and antiwear properties. At an optimal concentration of 0.05wt.% and a proper load of 50N, the mean friction coefficient and wear volume reduced by 65% and 60%, respectively. The remarkable lubricating effect of CDs-IL was attributed to the boundary tribofilm formed by absorption and deposition of CDs-IL on rubbing surfaces. The lubricating effect of CDs-IL especially antiwear effect greatly attenuated when the load was lower or higher than 50 N because the function of deposition tribofilm formed by CDs-IL was suppressed by the absorption tribofilm or tribochemical film derived from triethanolamine in base liquid, respectively.

The electrical properties of porous graphene (PG) are investigated by using the density functional theory (DFT) with the generalized gradient approximation (GGA). The addition of Boron and nitrogen impurities could change the semiconductor into the $n$ or $p$-type. Results showed that PG had pseudo-metal properties and a direct band gap. Furthermore, adding two impurities resulted in a greater decrease in the energy of the band gap as compared to the other states. In particular, when two impurities were of the boron type, the reduction was more tangible. Moreover, the addition of impurity could also increase the conductivity and pushed the electrical properties toward being a metal.

Manganese (Mn)-doped black iron oxide (Fe₃O₄) magnetic fluids in the system of Mn_xFe${}_{3-x}$O₄ were successfully synthesized from natural magnetite (iron sand) by using co-precipitation method at room temperature. The analyses of the small angle neutron scattering (SANS) data by applying a log-normal sphere with a mass fractal models for $x=0$ and $x=0.25$ and two log-normal spheres with a single mass fractal models for $x=0.5$, 0.75 and 1 revealed that the primary particles of the Mn_xFe${}_{3-x}$O₄ fluids tended to decrease from 3.8nm to 1.5nm along with the increasing fraction of Mn contents. The fractal dimension ($D$) increased from about 1.2 to 2.7 as the Mn contents were increasing; which physically represents an aggregation of the Mn_xFe${}_{3-x}$O₄ particles in the fluids growing up from 1 to 3 dimensions to consolidate a more compact structure. The magnetization curves of the fluids exhibited an increasing saturation magnetization from $x=0$ to $x=0.25$, and a decreasing on $x=0.5$ and 0.75, with the maximum achievement of $x=1$. These phenomena may probably be due to the combined effects, arising from cationic and dopant distributions, aggregation and its size, and also fractal dimension. Furthermore, the decrease of blocking temperature of the Mn_xFe${}_{3-x}$O₄ magnetic fluids could be associated with the reduced particle sizes, while the freezing temperature had its highest peak intensity when it collectively occurred with the blocking temperature at a similar point of about 270K.

In this study, we synthesized Hematite nano rings using hydrothermal treatment. The experimental results demonstrated that the (001)-orientated Hematite nano rings were produced in all of the obtained products. To determine the formation mechanism of the (001) orientation, the lowest three index crystal faces of Hematite, Hematite (001), Hematite (101), and Hematite (104), were investigated with the Cambridge Sequential Total Energy Package (CASTEP) within the Materials Studio software environment (MS5.5) using the density functional theory (DFT). Our theoretical results showed that Hematite (001), the Hematite crystal with the lowest surface energy, had the greatest Hematite nano ring growth. In addition, we present the growth process of the Hematite nano rings based on our experimental and theoretical results.

As devices scale down, we need to employ higher ion energy in the plasma etching to meet the requirements for critical dimensions. As a result, physical damage can be more severe. Since hydrogen can penetrate deeply into silicon due to its low mass compared to other species, there is a possibility of electrical degradation by deeply penetrated hydrogen. In this study, we demonstrated hydrogen-induced damage from the plasma etching process. Permeated hydrogen from the plasma etching process increases the amount of interface and bulk defects with increasing bias power, resulting in electrical degradation. Improvement of the device performance was possible via process modification using a rapid thermal anneal (RTA) directly after the hydrogen-containing plasma etching process and the hydrogen-free etching process.

This paper reports the transformation of HCP-Ti into BCC-Ti in the Ti–6Al–4V alloy induced by surface mechanical attrition treatment (SMAT). The processes of surface nanocrystallization (SNC) and phase transformation were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the average grain size in the surface layer gradually decreased with increasing SMAT duration, but plateaued at 10nm after 90min of SMAT, while the proportion of BCC-Ti in the surface layer gradually increased. The refined grains displayed equiaxed grain morphology with a random crystallographic orientation. The thermal stability of nanocrystalline BCC-Ti was investigated by subjecting it to isothermal annealing treatment in the temperature range of 450–800${}^{\circ }$C. BCC-Ti nanocrystallites were shown to exhibit excellent thermal stability up to 650${}^{\circ }$C, whereas those in HCP-Ti started to recrystallize at approximately 550${}^{\circ }$C.

The pH sensor of an extended gate field effect transistor (EGFET) with gallium nitride/silicon hybrid nanostructure is fabricated and analyzed. Si nanowires (NWs) are fabricated via the Ag-assisted electroless etching technique and are then covered by GaN NWs through plasma-enhanced chemical vapor deposition (PECVD). The GaN nanostructure is synthesized by introducing gallium oxide (Ga₂O₃) and nitrogen (N₂) for the growth of NWs. The GaN nanowires supply a larger surface area than that of the pristine Si NWs, where there is a better sensitivity for pH sensor. The GaN/Silicon hybrid sensors exhibit a sensitivity higher (50.4mV/pH) than that of pristine Si NWs sensors (41.2mV/pH). This GaN/Si hybrid pH sensor prepared by simple and low-cost method may be potentially applied for cheap biosensor devices.

Herein, a TiO₂ NTAs-Au-MoS₂ core–shell photoanode was constructed with the intention to fulfill the efficient transfer of photo-generated carriers to the photoelectrode’s surface. Au nanoparticles were decorated by a drop casting method, and the MoS₂ layer was deposited above the Au nanoparticles using a photoreduction-annealing process. Au nanoparticles were well dispersed on the inner wall of the TiO₂ nanotubes and covered by the MoS₂ layer, forming a core–shell nanostructure. The MoS₂ layer significantly improved the attachment between Au nanoparticles and TiO₂ NTAs, resulting in increased PEC stability and performance. Attributed to the excitation of Au nanoparticles’ localized surface plasmon resonance effect and visible light utilization of MoS₂, the TiO₂ NTAs-Au-MoS₂ core–shell photoanode exhibits greatly enhanced photocurrent density. An increase from 67$\mu$A/cm² to 234$\mu$A/cm² under Xe lamp illumination and from 2.6$\mu$A/cm² to 12.6$\mu$A/cm² under visible light illumination ($\lambda >420$nm) compared with the TiO₂ NTAs was observed.

SiO₂ nanoparticles modified with aminopropyl-triethoxysilane (APTES) were used as hard templates for preparing porous MoS₂. The method offers the advantages of simple steps, convenient operation, controllable pore size, and a specific surface area. Two morphologies of MoS₂ were obtained by using thiourea and L-cysteine as sulfur sources, respectively. Porous MoS₂ prepared by using thiourea had a smooth surface, whereas the surface of porous MoS₂ prepared with L-cysteine had many burrs. The MoS₂ nanomaterials with the respective morphologies were used to catalyze the hydrodeoxygenation (HDO) reaction. The activity of MoS₂ prepared with L-cysteine was lower than that prepared with thiourea. Transmission electron microscopy and X-ray diffraction analyses showed that MoS₂ had a large sheet-shaped structure and high crystallinity, leading to high reaction activity and high selectivity for cyclohexane. The reaction temperature also influenced the HDO significantly. The mechanism of hydrogenation of phenol was discussed.