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Clarifying hydrogen evolution and identifying the active hydrogen species are crucial to the understanding of the electrocatalytic hydrodechlorination (EHDC) mechanism. Here, monodisperse palladium nanoparticles (Pd NPs) are used as a model catalyst to demonstrate the potential-dependent evolutions of three hydrogen species, including adsorbed atomic hydrogen (H* ads ), absorbed atomic hydrogen (H* abs ), and molecular hydrogen (H 2 ) on Pd NPs, and then their effect on EHDC of 2,4-dichlorophenol (2,4-DCP). Our results show that H* ads , H* abs , and H 2 all emerge at -0.65 V (vs Ag/AgCl) and have increased amounts at more negative potentials, except for H* ads that exhibits a reversed trend with the potential varying from -0.85 to -0.95 V. Overall, the concentrations of these three species evolve in an order of H* abs < H* ads < H 2 in the potential range of -0.65 to -0.85 V, H* ads < H* abs < H 2 in -0.85 to -1.00 V, and H* ads < H 2 < H* abs in -1.00 to -1.10 V. By correlating the evolution of each hydrogen species with 2,4-DCP EHDC kinetics and efficiency, we find that H* ads is the active species, H* abs is inert, while H 2 bubbles are detrimental to the EHDC reaction. Accordingly, for an efficient EHDC reaction, a moderate potential is desired to yield sufficient H* ads and limit H 2 negative effect. Our work presents a systematic investigation on the reaction mechanism of EHDC on Pd catalysts, which should advance the application of EHDC technology in practical environmental remediation.

In order to discuss the effect of polymer coating layer on the Sn anode, the composition and morphology of the solid electrolyte interphase (SEI) film on the surface of Sn and Sn@PEO anode materials have been investigated. Compared with the bare cycled Sn electrode, the SEI on the surface of cycled Sn@PEO electrode is thinner, smoother, and more stable. Therefore, the Sn@PEO nanoparticles can basically keep the original appearance during cycling. Based on the results obtained from X-ray photoelectron spectroscopy (XPS), the SEI formed on the Sn@PEO electrode is characterized by inorganic components (LiCO)-rich outer layer and organic components-rich inner which could make the SEI more stable and inhibit the electrolyte immerging into the active materials. In particular, the elastic ion-conductive polyethylene oxide (PEO) coating could increase the toughness of SEI and allow the SEI to endure the stress variation in repetitive lithium insertion and extraction process. As a result, the Sn@PEO electrodes show significantly better capacity retention than bare Sn electrodes. The findings can serve as the theoretical foundation for the design of lithium-ion battery electrode with high energy density and long cycle life. [ABSTRACT FROM AUTHOR]

A novel, stable and sensitive non-enzymatic glucose biosensor based on bimetallic hollow Ag/Pt nanoparticles and the reduced graphene oxide (rGO) was obtained. The hybrid of bimetallic hollow Ag/Pt nanoparticles-reduced graphene oxide (HAg/PtNPs-rGO) was prepared by a galvanic replacement reaction and the thermal reduction of graphene oxide. Thermal reduction has been highly effective in producing graphene-like films which can render a stable substrate for hollow Ag/Pt nanoparticles. The morphology and composition of the prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectrometry and Fourier transform infrared spectra. Cyclic voltammetry measurements demonstrated that the biosensor decorated by HAg/PtNPs-rGO can directly detect glucose and show a superior electro catalytic activity. The results of amperometric method showed a desirable amperometric response with a sensitivity of 129.32 μA mM cm, a linear range of 0.003-7.72 mM (R = 0.9943), a fast response time (less than 3 s) and a low detection limit of 1.8 μM (S/N = 3). In addition, the fabricated sensor also had good selectivity, reproducibility and long-term stability. The sensor modified by HAg/PtNPs-rGO could make a promising application in glucose determination. [ABSTRACT FROM AUTHOR]

A selective adsorbent for Hg(II) was prepared by coating Fe 3 O 4 nanoparticles with SiO 2 which was further functionalized with thiol (–SH) group. The new adsorbent (Fe 3 O 4 @SiO 2 -SH) was shown to adsorb aqueous Hg(II) species in a wide range of pH (1.0–8.0) conditions. The Hg(II) adsorption capacity q e was more than 90.0 mg g −1 at pH > 3.0, and was slightly decreased to 84.6 mg g −1 under strong acidic conditions due to the electrostatic repulsion. The Langmuir isotherm model fitted the adsorption data better than the Freundlich, Temkin, and Dubinin-Radushkevich isotherms models. The maximum adsorption capacity of Fe 3 O 4 @SiO 2 -SH for Hg(II) was 132.0 mg g −1 . The adsorption kinetics were shown to follow the pseudo-second-order kinetic model, and the kinetic constant k 2 was 2.4 × 10 −3 g mg −1 min −1 . The magnetic retrieve of the newly-developed adsorbent was easily carried out via an external magnetic field, enabling both excellent adsorbent utilization and adsorption efficiency at high Hg(II) concentrations. [ABSTRACT FROM AUTHOR]

SnS is an important semiconductor and its performance depends greatly on its morphology and 3D architecture. So the synthesis for it with specific structures has been widely paid attention. Herein, a novel hollow nanoparticle-based SnS crystal product with microcluster-like 3D network hierarchitectures was developed, via a template-assisted solvothermal route in diethylene glycol (DEG) solvent, followed by annealing in N 2 atmosphere and subsequent corrosion of template by dilute acid. CaCO 3 nanoparticles were used as the template, SnCl 2 as the tin source, thiourea and l -cysteine hydrochloride monohydrate (Cys) as two different sulfur sources for a comparison study. Results show that successful fabrication of the hollow-structured SnS product mentioned above was achieved only in the case of using Cys as the sulfur source, mainly due to much stronger adhesion of Cys on CaCO 3 template and microcluster-like stacking patterns of CaCO 3 nanoparticles in DEG solvent. This novel 3D hierarchical SnS product owns 1–5 times higher specific surface area, unique hollow nanostructure units with rich mesopores inside the shells, and scattering-enhanced absorption in UV–vis light region, as against those previously reported micro-scale tin sulfide 3D hierarchitectures assembled by nanopetals, nanosheets, nanorods, nanobelts, etc. So it should have much more extensive and promising applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Enhanced 2,4-DCBA dechlorination with low intermediate products was achieved. • 2,4-DCBA removal by moveable Pd/AC was 5–194 folds faster than fixed catalysts. • High Pd loading, current, and acidity favored the dechlorination of 2,4-DCBA. • Excessive electrolyte inhibited the dechlorination of 2,4-DCBA. • Good longevity and recyclability of moveable Pd/AC catalyst was confirmed. Abstract In this study, a novel approach was developed for the dechlorination of 2,4-dichlorobenzoic acid (2,4-DCBA) via the combination of the moveable activated carbon (AC) supported palladium (Pd) nanoparticles and nickel (Ni) foam electrode. The morphology and chemical structure of Pd/AC catalyst was investigated by various characterization techniques, including SEM, TEM, EXS-mapping, XRD, and XPS. Pd nanoparticles was successfully loaded and dispersed on the AC, accompanied with the significantly enhanced reactivity. The removal rate of 2,4-DCBA by Ni electrode with moveable Pd/AC catalyst was 222, 25, and 5 folds higher than dispersed AC and Ni electrode system, chemical deposited Pd/Ni electrode, and electrodeposited Pd/Ni electrode, respectively. Compared with the conventional electrocatalytic reductive approach which deposited Pd on the Ni foam electrode, moveable Pd/AC catalyst possesses higher surface area, more atomic H∗ production and more active sites, favored mass transfer, and enhanced reactivity, without the consideration of catalyst loss and deactivation. The effects of Pd:AC mass ratio, constant current, initial solution pH, and electrolyte concentration on the dechlorination of 2,4-DCBA were studied. Generally, high Pd loading, constant current, and acidity favored the dechlorination of 2,4-DCBA, while excessive electrolyte would inhibit the dechlorination of 2,4-DCBA. Good longevity and recyclability of moveable Pd/AC catalyst was confirmed via consecutive experiments. The findings of the present study show that making the catalyst moveable is a promising strategy for electrocatalytic remediation technology. [ABSTRACT FROM AUTHOR]

Stabilized iron sulfide (FeS) nanoparticles have been proven effective in the adsorption of Hg from the water environment. However, previous work with these nanoparticles determined that the separation from the treated water was difficult and time-consuming. In this study, nanoscale FeS-Fe 3 O 4 nanocomposites were firstly synthesized with chitosan as the stabilizer (CTO-MFeS). Then, the Hg adsorption capacity and mechanism were studied. Results showed that the size of the prepared nanoparticles was about 20 nm and the specific surface area was 21.3 m 2 /g. Hg removal by the CTO-MFeS nanoparticles involved both adsorption and precipitation. Further investigation with XPS showed that Hg 2 + was adsorbed on the surface of the CTO-MFeS nanoparticles and reacted with CTO-MFeS to form HgS and [Fe (1 − x) Hg x ]S. It was also found as pH decreased below 4, the adsorption capacity of CTO-MFeS was significantly reduced that might be due to the dissolving of Fe. Additionally, the presence of Cl − resulted in the transformation of Hg 2 + to HgClx 2-x (x = 1, 2, 3, 4) that competed with OH in solution for Hg 2 + and therefore inhibited the adsorption of Hg. Our findings provide additional information that may be useful for a theoretical basis for Hg treatment in water environment. [ABSTRACT FROM AUTHOR]

Iron sulfide (FeS) nanoparticles were known for their excellent ability to scavenge aqueous Hg(II). However, the aggregation and oxidizability of FeS nanoparticles greatly restricted their practical application. This study developed an Al 2 O 3 -supported nanoscale FeS (FeS/Al 2 O 3 ) which effectively optimized the material performance. Characteristic data suggested that FeS/Al 2 O 3 (mass ratio of FeS to FeS/Al 2 O 3 is 30%) with a large specific surface area (142.7 m 2 g −1 ) could evenly distribute FeS, suppressing the aggregation of FeS successfully. The maximum enrichment capacity of Hg(II) on FeS/Al 2 O 3 achieved ∼313 mg/g at pH 6 and 30 °C. The pH studies indicated that alkaline environment strongly inhibited mercury uptake, while removal rate of 1 mg/L Hg(II) maintained a high level (>97.5%) over the pH range of 3–9. However, FeS/Al 2 O 3 loss was observed at low pH due to the acid corrosion. Additionally, the rates of Hg(II) reduction were almost unaffected over the range of 0.1–100 mM NaCl, but greatly inhibited by the presence of humid acid (HA). The synthetic FeS/Al 2 O 3 remained high mercury removal efficiency (over 95% in 1 mg/L Hg(II)) and low iron dissolution rate when preserved for 30 days, showing good long-term stability and remarkable application potential. [ABSTRACT FROM AUTHOR]

Multilayer Zn-doped SnO 2 nanospheres are successfully synthesized by using Sn/Zn bimetal-organic nanoparticles as precursor. These multilayer spheres are found to be very suitable for solving the critical volume expansion problem and mass transfer property due to its high surface area, small crystal size and hollow structure, which is critical for high capacity metal oxide electrodes for lithium-ion batteries. Moreover, the covalently interconnected three-dimensional graphene foams encapsulated these multilayer spheres are successfully obtained through self-assembly effect and chemical cross-linking of graphene oxide nanosheets. The graphene network could further greatly improve the cycling stability and rate capability of the Zn-doped SnO 2 spheres electrode due to its flexible buffering matrix and high electric conduction. As a result, the graphene encapsulating multilayer Zn-doped SnO 2 spheres anodes exhibit excellent rate capacity and a high reversible capacity of 446 mA h g −1 even after 1000 cycles at the current density of 1 A g −1 . These excellent electrochemical performances are ascribed to its large specific surface area, fast electron/ion transfer, and stable electrode structure. Furthermore, this strategy using covalently interconnected 3D graphene foams encapsulate the Zn-doped SnO 2 spheres not only develops a high performance anode material with long cycle life but also holds great promise for binder-free lithium ion batteries. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nano-Ni/Fe were synthesized in the presence of ultrasonic irradiation. [•] Ultrasonic irradiation can improve nano-Ni/Fe′ disparity and avoid agglomeration. [•] 2,4-DCP was first adsorbed by nano-Ni/Fe, then was quickly dechlorinated. [•] Factors of reductive dechlorination by nano-Ni/Fe were studied. [ABSTRACT FROM AUTHOR]

• The ZnO-rGO composites electrode was fabricated by self-assembly. • The agglomeration of nanoparticles and GO sheets was inhibited by self-assembly. • The sensitivity of this electrode to dopamine has been extremely improved. • This electrode has good reproducibility and anti-interference ability. This study introduces the self-assembly method to fabricate Zinc Oxide (ZnO) decorated reduced Graphene Oxide (ZnO-rGO) composites with higher sensitive for detection of dopamine (DA), one of the most common biomarkers of Parkinson's disease. The approach is reported to self-assembly Graphene Oxide (GO) and ZnO nanoparticles (NPs) modified by 3-aminopropyl triethoxysilane (APTES), forming ZnO-GO composites, then ZnO-rGO composites were obtained by electrochemical reduction of ZnO-GO composites. Utilizing differential pulse voltammetry (DPV), we found ZnO-rGO composites fabricated by the method of self-assembly reduced the agglomeration of ZnO and GO and showed a higher sensitivity for detection of DA than the dopamine electrochemical sensor previously reported. The fabricated sensor showed a linear dynamic range on 5–70 μM with a LOD of 0.167 μM (S/N = 3) and a sensitivity of 458nA/μM in response to DA. Finally, the as-prepared ZnO-rGO composite displayed an excellent detection recovery of 98.8 ~ 101.2% in human serum. [ABSTRACT FROM AUTHOR]