•Developed a facile one-pot microwave assisted synthesis of MoS2–Cd0.8Zn0.2S nanocomposites.•The as-prepared urchin-shaped composites have greatly enhanced photocatalytic activity in the water splitting reaction.•The thus prepared urchin-like MoS2–Cd0.8Zn0.2S nanocomposite exhibited greatly enhanced stability during water splitting into H2.A class of urchin-shaped nanocomposites composed of MoS2 and Cd0.8Zn0.2S nanoparticles were fabricated in this study, yielding the highest hydrogen evolution rate of 1401 μmol/g/h when they are applied as the photocatalysts of water splitting reaction. The greatly enhanced photocatalytic activity could last over 24 h. Such great improvement in the photocatalytic activity, which is nearly 11 times higher than that of pure CdS and 9 times of Cd0.7Zn0.3S, and 1.7 times of MoS2–CdS, may be attributed to that the one-step synthetic procedure resulted in tighter interfacial contact of the urchin-like MoS2–Cd0.8Zn0.2S composites. Specifically, solvothermal reaction of molybdenum(V) dimethyldithiocarbamate, diethyldithiocarbamato cadmium(II) and zinc di(benzimidazol-2-yl) disulphide took place simultaneously in one-pot. Characterizations with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) etc. illustrate that a class of novel urchin-shaped nanocomposite composed of MoS2 and Cd0.8Zn0.2S nanoparticles were formed in this one-pot synthesis. This study therefore presents a simple and effective route to prepare chalcogenide-based photocatalysts for more efficient production of hydrogen from water.

A high yield one-pot synthesis of β-amino alcohols from nitroarenes and 1,2-epoxides was developed, which utilizes inexpensive iron dust as a reducing agent and NH4Cl as the only additive in a 50% (v/v) ethanol solution. This new efficient synthetic approach tolerates a wide range of functionalities. The mild reaction conditions (e.g., 60 °C), together with the use of low cost and readily available starting materials, make this synthetic approach an attractive alternative to the current synthesis of β-amino alcohols.

A new class of oxygen reduction reaction (ORR) catalysts based on graphene quantum dots (GQDs) supported by graphene nanoribbons (GNRs) has been developed through a one-step simultaneous reduction reaction, leading to ultrahigh performance for O reduction with an excellent electrocatalytic activity (higher limiting current density and lower overpotential than those of platinum) and high selectivity and stability in alkaline media comparable to the best C-based ORR catalysts reported so far. Electron microscopy revealed numerous surface/edge defects on the GQD/GNR surfaces and at their interface to act as the active sites. This, coupled with efficient charge transfer between the intimately contacted GQDs and GNRs, rationalized the observed ultrahigh electrocatalytic performance for the resultant GQD-GNR hybrids. Thus, this study opens a new direction for developing low-cost, highly efficient, C-based ORR electrocatalysts.

A series of multi-heterostructured metal chalcogenides (CdS-Te, NiS/CdS-Te, and MoS2/CdS-Te) with a surprising shish-kebab-like structure have been synthesized via a one-step microwave-assisted pyrolysis of dithiocarbamate precursors in ethylene glycol. Subsequently, CdS-Te composites were exploited as a self-sacrificial template to craft various CdS-Te@(Pt, Pd) multi-heterostructures. Highly uniform dispersion and intimate interactions between CdS and multicomponent cocatalysts, together with improved separation of photogenerated carriers due to the presence of Te nanotubes (NTs) and trace CdTe, enable CdS-based heterostructured photocatalysts to exhibit greatly enhanced efficiency and stability in the photocatalytic production of H2. Thorough morphological characterizations revealed that the growth of metal sulfide/Te heterostructures originates from the growth of Te tubes, which is likely governed by diffusion-limited depletion of the Te precursor and the dissolution–crystallization process of Te seeds followed by the formation of metal sulfide kebabs.

•Developed a one-step synthesis of graphene co-doped with different halogen atoms.•The obtained graphene exhibits great electrocatalytic activity in the oxygen reduction reaction.•The chlorine–fluorine co-doped graphene has great stability in methanol crossover effect.•Experiments indicate that there are possible synergetic interactions between halogen dopants.Graphene co-doped with fluorine and chlorine heteroatoms was prepared through a one-step synthesis and was investigated as the oxygen reduction electrocatalysts. Voltammetric measurements show that fluorine and chlorine co-doped graphene has remarkable catalytic activity toward the electrochemical reduction of oxygen in alkaline solution. Besides having a high tolerance to methanol crossover effect, the co-doped graphene also showed a better stability than that of commercial Pt/C electrocatalysts and of the chlorine-doped graphene that was prepared by the same approach. The charge transfer resistance of the co-doped graphene was substantially lower than that of the chlorine-doped graphene, suggesting that there may exist a synergistic interaction between fluorine and chlorine dopants. The rapid synthetic method reported here provides an effective approach for future investigation of halogen (co-) doped graphene.Graphene co-doped with fluorine and chlorine was prepared through a one-step synthesis to greatly enhance its electrocatalytic activity and stability for oxygen reduction reaction.

•A cascade amplification strategy for electrochemical immunosensing was developed.•The method involves surface-initiated enzymatic polymerization, biobarcode probes assembly, and silver nanoparticles deposition.•This method can detect fetoprotein down to 0.046 pg/mL.•This new approach has good accuracy for the detection of AFP in clinical samples when compared with commercial tests.A cascade signal amplification strategy through combining surface-initiated enzymatic polymerization (SIEP) and the subsequent deposition of strepavidin functionalized silver nanoparticles (AgNPs) was proposed. The first step of constructing the electrochemical immunosensor involves covalently immobilizing capture antibody on a chitosan modified glass carbon electrode, which then catalyzes DNA addition of deoxynucleotides (dNTP) at the 3′-OH group by terminal deoxynucleotidyl transferase (TdT), leading to the formation of long single-stranded DNAs labeled with numerous biotins. Following the deposition of numerous strepavidin functionalized AgNPs on those long DNA chains, electrochemical stripping signal of silver was used to monitor the immunoreaction in KCl solution. Using α-fetoprotein as a model analyte, this amplification strategy could detect fetoprotein down to 0.046 pg/mL with a wide linear range from 0.1 pg/mL to 1.0 ng/mL. The achieved high sensitivity and good reproducibility suggest that this cascade signal amplification strategy has great potential for detecting biological samples and possibly clinical application.

This research presents a template-free solvothermal method which offers selective preparation of graphene ranging from two-dimensional sheets to 3-dimensional nanospheres. The thus prepared nanospheres have size-defined mesopores with a huge surface area and, after doping with nitrogen, exhibited stronger electrocatalytic activity toward oxygen reduction than commercial Pt/C catalysts.

Developing a low-cost route to synthesize mesoporous TS-1 (MTS-1) is of great importance because of its practical application in industry. Herein, we first synthesized a copolymer containing quaternary ammonium groups by a mesoporous template comprising inexpensive starting materials. Subsequently, waterglass (sodium metasilicate), TiCl3, and copolymer were dispersed in the preformed seeds emulsion, resulting in a gel for synthesizing MTS-1. The counterpart material (CTS-1) was also synthesized by the same procedure except for the absence of the copolymer. Compared with CTS-1, the MTS-1 exhibits good crystallinity and well-defined tetrahedral coordinated Ti species (TiIV) in the framework as well as excellent catalytic activity in the oxidation of bulky molecules, such as dibenzothiophene and benzyl phenyl sulfide. This feature may be attributed to the fact that the quaternary ammonium groups on copolymer facilitates the formation of the MFI structure and energetically incorporates the Ti species into the framework.

Noble-metal Pd and Pt catalysts with a wide range of surface wettability were fabricated through an electrochemical approach and were characterized with scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and atomic force microscopy. The importance of surface wettability of solid catalysts in multiphase reactions—especially their correlation to the nature of the studied chemical system—was investigated by reducing oxygen in an alkaline solution and oxidizing hydrogen peroxide and sodium formate in alkaline or buffered solutions at the as-prepared catalysts. These experiments illustrate that the nature of a multiphase reaction plays a critical role in determining the influence of surface wettability on the catalyst performance, providing a unique approach to decipher the reaction process. The investigation allows us to gain new insights into the electrochemical oxidation of sodium formate.Keywords: electrocatalysis; multiphase reactions; noble metals; surface wettability;

Novel Au-decorated Te hybrids with a tripod-shaped planar microstructure were prepared through a two-step hydrothermal process: the synthesis of Te single crystals and the subsequent self-sacrificial reaction of Te template with HAuCl4. Based on the influences of reaction temperature and solvent compositions on the as-obtained microstructures, a plausible mechanism was proposed to account for the formation of the tripod-shaped Te and Au/Te crystals. The as-prepared Au/Te hybrids have the sensitivity of 6.35 μA/ppb in the electrochemical detection of As(III), which represents the highest sensitivity reported in literature. The Au/Te sensor also has a low detection limit of 0.0026 ppb and could work in complex mixtures containing As(III), Cu(II) and other heavy metal ions, exhibiting excellent selectivity on As(III) and Cu(II) ions. The enhanced electrocatalytic property may be attributed to the synergetic interactions between the noble metal and semiconductor and the presence of a large number of active sites on the hybrids surface.Keywords: arsenic ions; Au/Te hybrids; electrochemical analysis; heavy metal ions; hydrothermal synthesis;

Reduced graphene oxide (rGO) and NiO composites were prepared with an environmentally friendly method, in which hydrogen gas was employed as the reducing agent to convert reduced graphene oxides. Our study indicates that the success of this new approach is because NiO not only is an additive of the composites but also acts as a catalyst to facilitate the reduction. Characterization with scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and X-ray powder diffraction illustrates that the as-prepared rGO/NiO composites have a three-dimensional flowerlike hierarchical structure, which prevents graphene from taking face to face aggregation and therefore greatly improves the stability of the composite materials. A hybrid capacitor electrode made of the NiO/rGO composites shows great performance, in which the maximum specific capacitance is close to 428 F g–1 at a discharge current density of 0.38 A g–1 in a 6.0 M KOH electrolyte.

This study investigated electrochemical detection of human hepatitis B and papilloma viruses using electrochemical impedance spectroscopy technique. The sensor was fabricated by electrochemically depositing Au nanoparticles on the in situ prepared single walled carbon nanotube (SWCNTs) arrays, followed by the self-assembly of single-stranded probe DNA on the SWCNTs/Au platform. The as-prepared electrochemical sensor could detect lower than 1 attomole complimentary hepatitis B single-stranded DNA (ssDNA), which corresponds to having 600 ssDNA molecules in a 1.0 mL sample. For a 1-base mismatched hepatitis B ssDNA, the experimental detection limit is 0.1 pmol. When being applied to detect 24-base papilloma virus ssDNA, the experimentally determined low detection limit is 1 attomole. In addition to the low detection limit, the SWCNTs/Au/ssDNA sensor also showed great stability, where after being kept in a refrigerator for a month at a temperature 4–8 °C its charge transfer resistance decreased by less than 1%. The sensor could be conveniently regenerated via dehybridization in hot water. Both aligned and random SWCNTs arrays have been investigated in this study and there was nearly no difference in the low limit in the detection of hepatitis B and papilloma viruses. This study illustrates that combining Au nanoparticles with the in situ fabricated SWCNTs array is a promising platform for ultrasensitive biosensing.Highlights► Both random and aligned SWCNTs/Au arrays were in situ prepared on Si/SiO2 substrate. ► The array electrodes could detect lower than 1 attomole complimentary 21-base Hepatitis B DNA. ► The array electrodes could detect lower than 1 attomole complimentary 24-base papilloma DNA. ► The electrodes were capable of detecting one-base mismatched DNAs. ► The electrodes showed good stability and could be regenerated conveniently.

Using Au nanoparticles to catalyze the oxidation of alcohols has garnered increasing attention due to its potential application in direct alcohol fuel cells. In this research Te@Au core-shell hybrids were fabricated for the catalytic oxidation of ethanol, where the preparation procedure involved the initial production of Te crystals with different microstructures and the subsequent utilization of the Te crystal as a template and reducing agent for the production of Te@Au hybrids. The as-prepared core-shell hybrids were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques. Electrochemical measurements illustrate that the hybrids have great electrocatalytic activity and stability toward ethanol oxidation in alkaline media. The enhanced electrocatalytic property may be attributed to the cooperative effects between the metal and semiconductor and the presence of a large number of active sites on the hybrids surface.Highlights► A simple template/reduction approach is developed for fabricating Te@Au hybrids. ► The Te@Au hybrid electrode exhibits much higher electrocatalytic activity in ethanol oxidation. ► The hybrids have higher tolerance on the poisoning by intermediate products. ► The effective surface area was greatly increased due to the formation of Au nanoparticles.

An electrochemical sensor was constructed via self-assembly of chiral metal complexes Λ-[Os(phen)3(ClO4)2] on reduced graphene oxide (rGO) sheet. Cyclic voltammetry and differential pulse voltammetry illustrate that the sensor could detect 1,1′-2-binaphthol lower than 10 μM. The response current of S-1,1′-2-binaphthol is 1.4 times higher than that of R-1,1′-2-binaphthol. A linear concentration range was attained for the response peak current. In comparison to clay/indium tin oxide substrate based chiral sensor, rGO has clearly enhanced the sensitivity of chiral sensing. Preliminary measurement indicates that the rGO/Λ-[Os(phen)3]2 + sensor can also be applied to determine compositions of a chiral mixture.Highlights► Prepared functionalized hybrid film based on reduced graphene oxide. ► The hybrid film exhibited greatly improved sensitivity and selectivity in chiral sensing. ► There is a linear relationship between the peak current and the concentration of chiral moleculs. ► The as-prepared sensor could analyze a mixture of binaphthol chiral molecules.

A new platform based on electrochemical growth of Au nanoparticles on horizontally aligned single walled carbon nanotube (SWCNT) array was developed for ultrasensitive DNA detection. The as-prepared DNA-functionalized SWCNT-Au platform, in which every gold-coated SWCNT acts as an isolated micro electrode, could detect lower than 10 zmol complimentary 10-base DNA, which corresponded to having 6 DNA molecules in a 1 mL sample solution. For a 1-base mismatched DNA, the experimental detection limit was 100 amol. A linear relationship between the change of charge transfer resistance and target DNA concentration was achieved at low concentration range. Over the extended DNA concentration range, the change of charge transfer resistance was found to have a linear relationship with respect to the logarithm of the target DNA concentration. The sensor also showed great stability and could be conveniently regenerated via dehybridization in hot water. The significant improvement in sensitivity illustrates that combining Au nanoparticles with the on-site fabricated SWCNT array represents a promising platform for achieving ultrasensitive biosensor.Highlights► Developed an efficient procedure of fabricating SWCNT-Au array electrode. ► The as-prepared array electrode could detect lower than 10 zmol complimentary 10-base DNA. ► The electrode was capable of detecting one-base mismatched DNA. ► The SWCNT-Au electrode showed good stability and could be regenerated conveniently after each measurement.

Thermal decomposition of N,N′-diphenylguanidine (DPG) was investigated by simultaneous TG/DSC-FTIR techniques under nonisothermal conditions. Online FTIR measurements illustrate that aniline is a major product of DPG decomposition. The observation that the activation energy depends on the extent of conversion indicates that the DPG decomposition kinetics features multiple processes. The initial elimination of aniline from DPG involves two pathways because of the isomerization of DPG. Mass spectrometry and thin film chromatography suggest that there are two major intermediate products with the major one of C21N3H17. The most probable kinetic model deduced through multivariate nonlinear regression method agrees well with the experimental data with a correlation coefficient of 0.9998. The temperature-independent function of conversion f(α), activation energy E and the pre-exponential factor A of DPG decomposition was also established through model-fitting method in this research.

Te@Pd core–shell hybrids were prepared in this study, in which a pine leaf-shaped microstructure was obtained through controlling the synthesis kinetics of single crystal Te. The as-prepared Te was subsequently utilized as the substrate for Pd coating. These core–shell particles were characterized with scanning and transmission electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, and energy dispersive X-ray spectroscopy. When being applied as a catalyst in bromobenzene and phenylboronic acid reaction, 100% conversion of bromobenzene was achieved in less than 3 h, which was much shorter than that required by the reactions using graphene oxide supported Pd catalyst (4 h) or the commercial Pd/C catalyst (>6 h). The Te@Pd core–shell catalyst could be easily recovered from the reaction solution and be used repeatedly. The high catalytic activity of Te@Pd hybrids is attributed to their unique microstructure.

Copper oxide nanoparticles (COs) were electrochemically deposited on horizontally aligned single-walled carbon nanotube arrays (COs-aSWCNT) on SiO2/Si wafer, where X-ray photoelectron spectroscopy shows that compositions of COs are Cu2O and CuO with a ratio of 2 to 1. The as-prepared COs-aSWCNT electrode exhibited synergistic electrocatalytic activity on the oxidation of glucose in alkaline media with a rapid response time of less than 2 s and a high sensitivity of 16.2 μA μM− 1. This new sensor has two useful linear regions of glucose concentration and has an experimental detection limit of 20 nM. In the presence of physiological level ascorbic acid (0.1 mM), the experimental detection limit of glucose increases to 50 nM with a sensitivity of 1.31 μA μM− 1.

An indium tin oxide (ITO) electrode coated with monolayer TiO2/[Ru(phen)2(dC18bpy)]2+ (phen = 1,10-phenanthroline, dC18bpy = 4,4′-dioctadecyl-2,2′-bipyridyl) hybrid film (denoted as ITO/TiO2-Ru) has been prepared using the modified Langmuir-Blodgett (LB) method, and the electrocatalytic oxidation of mononucleotide of guanosine 5′-monophosphate (GMP) on an ITO/TiO2-Ru electrode after Pd-photodeposition (denoted as ITO/TiO2-Ru/Pd) has been studied. Atomic force microscopy reveals that the single-layered hybrid film of TiO2 nanosheets/[Ru(phen)2(dC18bpy)]2+ is closely packed at a surface pressure of 25 mN m−1 and has a thickness of (3.20 ± 0.5) nm. X-ray photoelectron spectra show the formation of Pd nanoparticles on the surface of hybrid film with radii of 20–200 nm by the reduction of [Pd(NH3)4]2+ under light irradiation. When it is applied to oxidize GMP, a larger catalytic oxidative current is achieved on the ITO/TiO2-Ru/Pd electrode at the external potential above 700 mV (vs. Ag|AgCl|KCl) in comparison with the naked ITO electrode and ITO/TiO2-Ru electrode. Such a result indicates that the Pd nanoparticles are able to hamper the combination of electron hole pairs and reduce the counterwork of insulating long alkyl chains of amphiphilic Ru(II) complexes, and thus develops the electron transfer efficiency and produces the enhanced redox current.

A simple route to fabricate tellurium (Te) thin film with a well-defined two-dimensional nanostructure is presented in this study. The method involves dip-coating and subsequently pyrolyzing a single-source molecular precursor diethyldithiocarbamato tellurium (TDEC) onto a glass substrate. The pyrolysis temperature and the initial thickness (đ) of TDEC film exhibited strong influence on the morphology of Te film, where films composed of uniform Te nanoflakes have been obtained at 440 °C and đ ≈ 490 nm. Investigations on the thermodynamic properties of TDEC through thermogravimetry, differential thermogravimetry, and differential scanning calorimetry techniques suggest that the production of Te from TDEC features random and continuous nucleation, shedding light on the possible growth mechanism of the two-dimensional Te film.

An indium tin oxide (ITO) electrode modified with monolayer clay/[Ru(phen)2(dC18bpy)]2+ (phen=1,10-phenanthroline, dC18bpy = 4,4′-dioctadecyl-2,2′ bipyridyl) hybrid film has been fabricated by the Langmuir-Blodgett (LB) method. Atomic force microscopy revealed that the single-layered hybrid film of clay/[Ru(phen)2(dC18bpy)]2+ (denoted as Clay-Ru) was closely packed at a surface pressure of 25 mN·m−1 and had a thickness of 3.4±0.5 nm. Cyclic voltammograms showed that the redox current of Ru(II) complex decreased when incorporated into the clay film, suggesting that the clay layer acts as a barrier against electron transfer. When applied to oxidizing the mononucleotide of guanosine 5′-monophosphate (GMP), a large catalytic oxidative current was achieved on the Clay-Ru(II) modified ITO electrode at the external potential above 900 mV (vs. Ag|AgCl|KCl) and, more significantly, this response was further enhanced by light irradiation (λ>360 nm), in which the photocurrent is increased about 11 times in comparison with that of a bare ITO. Mechanism of the photoelectrocatalytic effect was proposed in terms of the reduction of the photoelectrochemically generated Ru(III) complex in the Clay-Ru film by GMP.