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[Display omitted] • The influence of C/N dual-doping in MoS 2 based sputtered films was investigated. • The lamellar structure of MoS 2 was maintained with high doping level and low S/Mo. • The balance between mechanical properties and lubricating performance was achieved by adjusting the content of C/N dopants. Transition metal dichalcogenides (TMDs) show poor mechanical properties and weak corrosion and oxidation resistance in ambient atmosphere, which results in the limit application and the lower work life. Doping TMDs based films with the enhanced performance show the potential to apply in harsh environment. The C/N dual-doping Mo-S-C-N films were deposited by magnetron sputtering, and the evolution of alternative microstructure composed of TMDs phase and amorphous inclusions was analyzed. The enhancement on mechanical, tribological and anti-corrosion properties of films with C/N dual-doping were evaluated. The strengthened TMDs phase and inclusions with MoC x /MoN x hard phase result in the improvement of mechanical properties (hardness 8.57–19.09 GPa). The superior tribological performance was obtained from film with 10.67 at. % of C and 17.36 at. % of N (wear rate 8.24 × 10-7 mm3/Nm, average friction coefficient (CoF) 0.188) and film with 14.87 at. % of C and 15.02 at. % of N (wear rate 8.02 × 10-7 mm3/Nm, average CoF 0.166). The balance between the effect of lubricating phase and mechanical performance strengthen by C/N dopants were achieved in these two films. The passivation of reactive sites in MoS 2 leads to the improvement of corrosion resistance, while excessive dopants induce more pathways for corrosive medium, which leads to the corrosion failure of films. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carrier injection hybrid structure from quantum well to surface quantum dots (SQDs) • All hybrid structures obtain an enhancement for PL intensity due to carrier injection. • Localized energy states through the 2.5 nm spacer impact carrier tunneling. • Carrier injection from quantum well to wetting-layer of SQDs, then loss to surface. • Facilitate SQD heterostructures to architect surface sensitive detection devices. This work exploits carrier injection hybrid structures in which carriers are injected into a layer of In 0.4 Ga 0.6 As surface quantum dots (SQDs) from an adjacent In 0.15 Ga 0.85 As quantum well (QW) as a function of spacer thickness from 10 nm down to 2.5 nm. Photoluminescence (PL) measurements verify that all such hybrid structures indeed have carriers collected into the QW and subsequently obtain an enhancement for PL intensity over that of the reference SQDs. The hybrid structure with the 2.5 nm spacer obtains the best carrier injection efficiency, due to the strongest coupling between the QW and the SQDs, while a thicker spacer results in less carrier injection from decreased quantum tunneling. However, the carrier injection is less efficient than expected. This is due to the fact that the QW confined energy states line up with the broad wetting layer (WL) energy states of SQDs of our test samples, leading to resonant carrier tunneling from the QW to the WL. Thus, there is significant carrier loss through tunneling into the WL of SQDs and then to surface states via nonradiative recombination. This characteristic must be considered in the design of surface sensitive detection devices using SQD injection structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synergistic lubrication of a combination of GML and N888 OFMs are performed by MD simulations. • The number ratio of 3:1 of GML to N888 shows the best synergistic lubrication. • High shear velocity damages adsorption film and results in high friction. • Synergistic effect is attributed to the interface slip rather than interlaminar shear. The synergistic effect of organic friction modifiers (OFMs) combining glycerol monolaurate (GML) and tri-n-octylamine (N888) in base oil is studied by molecular dynamics simulations. The adsorption and shear behaviors indicate that the triple-chains N888 molecules intersperse among the long-chain GLM molecules to form an intercoordination adsorption film. The system with a number ratio of 3:1 of GML to N888 shows a better synergistic lubrication with the lowest friction coefficient. The chemisorption of GML molecules on Fe 2 O 3 surface is verified by density function theory. High shear velocity accompanying friction heat causes adsorption film breakage and high friction, while contact pressure conduces to friction reduction. The synergistic lubrication is attributed to the interface slip between base oil and OFM films, rather than the interlaminar shear caused by an imbalanced combination or high shear velocity. [ABSTRACT FROM AUTHOR]

In this study, the graphene oxide was covalently modified by amino terminated polydimethylsiloxane (PDMS) through amidation reaction. And the membranes of the graphene oxide (GO), reduced graphene oxide (RGO) and PDMS-covalently modified graphene were prepared respectively by a vacuum filtration method, and the wettability of these membranes were investigated. Infrared spectroscopy, Raman, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetry analysis combined with dispersion ability indicated that PDMS chains were successfully grafted on the surface of graphene oxide sheets. The morphology of the prepared membranes had smooth surface and well-stacked structure in the cross-section indicated by the scanning electron microscope and EDS-mapping. The contact angle measurements indicated that the PDMS-modified graphene membrane with water contact angle 129.5° showed increased hydrophobicity compared with GO and RGO membranes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous and hollow 1D SnO 2 /Zn 2 SnO 4 composites are prepared by electrospinning. • UV light enhanced excellent TEA gas-sensing property can be primarily observed. • Greatly reduced working temperature of 120 °C and superior selectivity are gained. • Good practicality of gas sensors for food spoilage evaluation is valuable. • Enhanced mechanism is derived from the accelerated surface electron migration. Porous and hollow SnO 2 /Zn 2 SnO 4 composites with typical one-dimensional (1D) structure have been synthesized by adjusting the amounts of 2-methylimidazole zinc salt (ZIF-8) added in the precursor solution through a modified electrospinning technology. Compared with the gas-sensing performance of different samples detected in the normal condition, it is confirmed that the optimal working temperature can be markedly decreased from 260 to 120 °C under UV light irradiation, along with the substantially improved gas selectivity. In addition, SnO 2 /Zn 2 SnO 4 heterostructures exhibit a higher response (increases from 1.7 to 2.8) and faster response/recovery times (decreases from 24/154 to 14/42 s) to triethylamine (TEA) than that of the pure SnO 2. Significantly, the good practicality of gas sensors for food spoilage evaluation could be testified by effectively detecting the gas released during the putridity of prawns. UV light enhanced surface electron migration mainly contributes to the elevated synergistic effect between the formation of n-n heterojunction and tunable surface/interface electron transport behavior, as well as the adsorption and desorption of TEA molecules on the surface of the sensing materials. [ABSTRACT FROM AUTHOR]

Highlights: [•] PPy nanoparticles have been fabricated with the help of Triton X-100 micelles. [•] PPy nanoparticles have been first utilized in SAW gas sensor. [•] The responses of the sensors were linearly associated with the acetone concentrations in the range from 5.5ppm to 80ppm. [ABSTRACT FROM AUTHOR]

Ce-doped CdS quantum dot (QD) sensitized TiO 2 nanorods films on FTO substrates are for the first time prepared by a combination of hydrothermal and successive ionic layer adsorption and reaction (SILAR) method. The physicochemical properties of as-prepared samples are examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet–visible spectrometry (UV–vis). The as-prepared Ce-CdS QD sensitized TiO 2 nanorods photoelectrodes is applied into photoelectrochemical (PEC) cells to investigate their PEC properties, including the photocurrent density and incident photon-to-current conversion efficiency (IPCE), which exhibit a maximum 1.4-time enhancement in photocurrent density and 1.6-time enhancement in IPCE value, compared with undoped photoelectrode. Furthermore, a maximum 1.4-time higher formic acid yields was obtained in a versatile photoanode-driven PEC CO 2 reduction system. The results of electrochemical analysis show that the Ce-CdS QDs/TiO 2 photoelectrodes exhibit an increased visible light absorbance, a higher carrier density, a longer electron lifetime and more effective separation of photogenerated electron-hole pairs. This is most probably due to the existence of Ce 4f electronic states in the mid-gap region of Ce-CdS QDs, which is confirmed by a simple theoretical calculation and a redox couple Ce 3+ /Ce 4+ accelerating the photogenerated holes migration. The study demonstrates that the variable valency Ce-doping may be a promising approach to achieve high photoelectric conversion efficiency for chalcogenides semiconductors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The asymmetric orbital hybridization improves adsorption of heavy metal cations. • The polarizations of ions with 3 s 3 p 3 d are stronger than that with 3 s 3 p hybridization. • Polarization-induced covalent bonds exist at siloxane surfaces due to asymmetric response. • The contribution of asymmetric response to total adsorption energy was quantified. The interactions between heavy metal cations and charged surfaces are major processes responsible for the deactivation/activation of heavy metals, attracting special interest in both agricultural and environmental issues. The traditional view argues that the interactions between heavy metal and hydroxyl surface are primarily controlled by electrostatic forces and coordination-covalent bonds, while the interactions between heavy metal and siloxane surface are solely determined by electrostatic forces. A theory of asymmetric orbital hybridization was applied in this study to investigate the interactions between metal cations and charged surfaces. New surface reactions, polarization-enhanced induction forces (PEIF) and polarization-induced covalent bonds (PICB) between heavy metal cations (Cu2+ and Zn2+) and O atoms of charged siloxane surfaces, were discovered, and their respective contributions were quantified using asymmetric orbital hybridization theory. Both PEIF and PICB for metal cations with 3 s 3 p z 3 d z2 hybridization are stronger than those with sp z hybridization. For example, the proportion of covalent bonds in the overall adsorption energy is lower for Ca2+ with 3 s 3 p z hybridization (28.92 %) compared to Cu2+ with 3 s 3 p z 3 d z2 (32.77 %). The new surface reactions based on asymmetric orbital hybridization determine the adsorption selectivity of heavy metal cations and strongly affect their removal in wastewater. The removal efficiency of heavy metals can be regulated through the enhancements of hydroxyl groups, electric field strength, and orbital hybridization effects at the clay mineral surfaces. [ABSTRACT FROM AUTHOR]

Synopsis: A sustainable approach for the synthesis of noble-metal-free MoS 2 /Zn 0.5 Cd 0.5 S heterostructures with W/Z phase junctions with enhanced visible-light-driven photocatalytic hydrogen evolution and stability is reported. [Display omitted] • The noble-metal-free MoS 2 /Zn 0.5 Cd 0.5 S with W/Z phase junctions were prepared successfully. • Appropriate MoS 2 modification can enhance the separation efficiency of the charge carriers. • The 3%MoS 2 /Zn 0.5 Cd 0.5 S showed optimal visible-light photocatalytic hydrogen production. • The ESR spectra indicated that O 2 – and h+ played a major role during the degradation process. • The enhanced photocatalysis ascribed to interfacial optimization of double heterojunction. A series of composite heterojunction-MoS 2 /Zn 0.5 Cd 0.5 S photocatalysts free of noble metal ions was prepared using a simple hydrothermal method. The X-ray diffraction spectra of the MoS 2 /Zn 0.5 Cd 0.5 S composites exhibit three strong intensive peaks, thereby explaining the existence of wurtzite (CdS) and zinc blende (ZnS) in the form of the wurtzite/zinc-blende phase junctions. Microstructural studies indicate that the sample displays a typical cubic crystal structure and that the MoS 2 with flower-like structure uniformly wraps the granular Zn 0.5 Cd 0.5 S. X-ray photoelectron, Fourier transform infrared, and UV–Vis diffuse reflectance spectroscopic methods confirm that the heterojunction, which possesses outstanding photoresponse ability, is constructed between Zn 0.5 Cd 0.5 S nanoparticles and MoS 2 nanoflowers. The fluorescence spectroscopy, surface photocurrent spectroscopy, and electrochemical studies indicate that Zn 0.5 Cd 0.5 S nanoparticles with specific amount of MoS 2 nanoflowers can effectively suppress the recombination of photoinduced charge carriers of the composites. Therefore, pristine Zn 0.5 Cd 0.5 S nanoparticles loaded with 3%MoS 2 exhibit optimum performance of hydrogen production (388.2 μmol/h), which is 1.3 times that of pristine Zn 0.5 Cd 0.5 S nanoparticles. A plausible mechanism for enhanced photocatalysis is provided in terms of the heterojunction assisted effective separation of charge carriers that are generated by irradiation. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2D flower-like In 2 O 3 /ZnO composite derived from In 2 O 3 precursor/ZIF-8 is gained. • Composite has flower-like In 2 O 3 /ZnO structure composed of needle-like nanorods. • Sensors show an excellent gas-sensing response of 188.01 to 100 ppm TEA at 120 °C. • Mechanism is mainly due to the accelerated multi-orientation electron transport. • In 2 O 3 -based sensors can be used for actual detecting area of seafood storage. Flower-like In 2 O 3 /ZnO heterostructures consisting of the assembled needle-like nanorods derived from In 2 O 3 precursor/ZIF-8 have been prepared by a two-step approach. Flower-like In 2 O 3 /ZnO structures can be achieved by adjusting the nucleation competition and crystal surface matching of In 2 O 3 and ZnO, leading to the enhancement of gas adsorption on the surface, chemical reaction kinetics, and the electron transport efficiency. In/Zn-2 sensors exhibit excellent gas-sensing response value of 188.01 to 100 ppm triethylamine at 120 °C as well as good gas selectivity, long-term stability, and linear relationship compared with pure In 2 O 3 , mainly attributed to the accelerated multi-orientation electron transport mechanism within flower-like In 2 O 3 /ZnO heterostructures. In addition, In/Zn-2 samples can be utilized to detect the practical triethylamine gas released during the storage of marine organism (fishes). [ABSTRACT FROM AUTHOR]

[Display omitted] • SrFe 12 O 19 /MoS 2 heterojunction composite are synthesized via hydrothermal method. • The exposed interface reduce the recombination rate of the photogenerated carrier. • The composite achieved high degradation rate with magnetic recovery ability. Photocatalysis is one of the most promising technologies in wastewater treatment. Efficient degradation under visible light and the recovery capability of the photocatalyst are crucial in real-word applications. Herein, M−type SrFe 12 O 19 was integrated into the surface of flowerlike MoS 2 microsphere via the hydrothermal method. As-prepared SrFe 12 O 19 /MoS 2 composite photocatalyst has effective visible light response and magnetic recovery ability. The SrFe 12 O 19 /MoS 2 composite achieved 97% degradation rate for methylene blue under visible light. The photocatalytic reaction rate of the SrFe 12 O 19 /MoS 2 composite was nearly twice that of pure MoS 2. Transient steady-state fluorescence spectrometry and electrochemical spectrometry revealed that an appropriate amount of SrFe 12 O 19 effectively improves the charge transfer rate and accelerates photoinduced charge carrier separation. The possible photocatalytic degradation mechanism of the SrFe 12 O 19 /MoS 2 composite with the p–n heterojunction was also examined. [ABSTRACT FROM AUTHOR]

The obscurity in selectivity mechanism has resulted in dilemmas in the research of selectivity properties of metal oxide semiconductor (MOS) gas sensing materials. In this work, selectivity mechanism of ZnO nanorod arrays to CH 3 OH is revealed by systematically simulating response and recovery reactions of three gas molecules (CH 3 OH, NH 3 and CO) based on density functional theory (DFT). Results suggest that selectivity to CH 3 OH is due to three factors: i. Response reaction of CH 3 OH on ZnO (1 0  1 -  0) is most exothermic, which is main reason for the selectivity against NH 3 . ii. Intermediates as well as products oxidized from CH 3 OH have strongest absorption ability, which hinders reabsorption of O 2 molecule, mainly leading to selectivity against CO. iii. H adatoms dissociated from CH 3 OH transfer most electrons to ZnO surface layers, which is also responsible for the selectivity. This work provides a new insight into selectivity mechanism and a practicable method to predict selectivity properties of MOSs. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, we succeeded in accelerating the L10 ordering transition of FePt thin films by employing amorphous Ni–Al as underlayers. The coercivity H c =5kOe and ordering parameter S =0.67 of FePt thin films deposited on a Ni–Al underlayer with a thickness of ∼5nm after 380°C annealing for 30min are significantly higher than those H c =0.4kOe and S =0.35 of the films without the Ni–Al underlayer. The L10 ordering process of and the coercivity of FePt thin films can be significantly tuned by varying the thickness of the Ni–Al underlayer. [Copyright &y& Elsevier]

• Hierarchical C-N/Co/Ti composite derived from MOF/TBOT precursor is obtained. • Structure consists of dodecahedron-like particles covered with twisted nanotubes. • Ti and Co are effectively separated in the upper and lower ends of nanotubes. • C-N/Co/Ti eletrocatalyst exhibits superior ORR properties than that of Pt/C. • Novel mechanism is ascribed from the phase composition and microstructure. C-N/Co/Ti composites derived from ZIF-67@TiO 2 precursors have been fabricated by a facile thermal treatment process. The morphology and composition are highly dependent on the available parameters inferring of exact hydrolysis of tetrabutyl titanate and sintering temperature. The obtained hierarchical microstructure is composed of numerous dodecahedron-like hollow boxes decorated with in-situ growth of size-tunable and twisting nanotubes on surfaces. The effective elemental separation of Ti and Co on the upper and lower ends of nanotubes can be realized by regulating the ionic migration and crystalline phase formation process at a high temperature. The as-prepared C-N/Co/Ti composites exhibit the enhanced electrocatalytic activities to oxygen reduction reaction (ORR) via a favorable four-electron pathway and the desired reaction kinetics with the low Tafel slope (67.8 mV dec−1), as well as the excellent methanol tolerance in comparison with the Pt/C electrocatalysts. The superior ORR electrocatalytic performance would be mainly contributed to the combination of the designed multi-phase composition, the enhanced surface adsorption/desorption, the modified surface/interface electron transfer mechanism, and the constructed Co/Ti double-active sites on different locations of microstructure. The present work presents a new insight for the synthesis of C-N-based inorganic composite with outstanding electrocatalytic behavior for ORR process. [ABSTRACT FROM AUTHOR]