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Abstract: A novel electrochemical sensor for chlorophenols was fabricated by using the Pd-graphene nanocomposite and ions liquid. The Pd-graphene nanocomposite was prepared via a sonoelectrochemical route, and the possible formation mechanism was proposed. Transmission electron microscopy, scanning electron microscopy, X-ray diffraction and Raman spectrum were used for the characterization of structure and morphology of the nanocomposite. The experimental results showed that Pd nanospheres comprised of small Pd nanoparticles were uniformly attached on graphene sheets. The electrocatalytic properties were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which indicated that the Pd-graphene nanocomposite had high activity for chlorophenol oxidation. Herein, 2-chlorophenol was selected as the model molecules. The results showed that graphene played an important role in the fabrication of the chlorophenols sensor. The nanocomposite with large electrochemical active surface led to the excellent electrocatalytic activity, and ionic liquid further enhanced the catalytic activity of Pd-graphene for chlorophenols. [Copyright &y& Elsevier]

Abstract: The gold nanoparticles/colloidal carbon sphere hybrid material was used for the immobilization of protein, and was developed in biosensing. The hybrid material was fabricated by the assembly of gold nanoparticles onto the surface of colloidal carbon spheres, which constructed a 3D antibody immobilization matrix on the glass carbon electrode and made the immobilized biomolecules hold high stability and bioactivity. After the sandwich-type immunoreaction, the formed HRP-labeled immunoconjugate showed good enzymatic activity for the oxidation of o-phenylenediamine by H2O2. The approach provided a linear response range between 5 and 250ng/mL with a detection limit of 1.8ng/mL. The immunosensor showed good precision, acceptable stability and reproducibility and could be used for the detection of human IgG in real samples, which provided a potential alternative tool for the detection of protein in clinical laboratory. [ABSTRACT FROM AUTHOR]

Abstract: Acidic and neutral Nafion® 115 perfluorosulphonate membranes have been modified by in situ polymerization of pyrrole using Fe(III) and H2O2 as oxidizing agents, in order to decrease methanol crossover in direct methanol fuel cells. Improved selectivities for proton over methanol transport and improved fuel cell performances were only obtained with membranes that were modified while in the acid form. Use of Fe(III) as the oxidizing agent can produce a large decrease in methanol crossover, but causes polypyrrole deposition on the surface of the membrane. This increases the resistance of the membrane, and leads to poor fuel cell performances due to poor bonding with the electrodes. Surface polypyrrole deposition can be minimized, and surface polypyrrole can be removed, by using H2O2. The use of Nafion in its tetrabutylammonium form leads to very low methanol permeabilities, and appears to offer potential for manipulating the location of polypyrrole within the Nafion structure. [Copyright &y& Elsevier]

• A hybrid electrode made of (TEAPW12) and activated carbon (AC) outperforms AC in a high-V organic electrolyte supercapacitor • The inorganic cluster undergoes multi-electron reactions in the hybrid material, even in an aprotic organic electrolyte. • Volumetric capacitance increases by ~36% with polyoxometalates hybridization without sacrificing voltage window. • We are demonstrating for the first time the effective use of polyoxometalates in aprotic electrolyte supercapacitors. Polyoxometalates (POMs) have been shown to work as faradaic additives to activated carbon (AC) in acidic aqueous electrolytes. Yet, their use in organic media allows not only for added capacity but also higher voltage. Here we show that the tetraethylammonium derivative of phosphotungstate [PW 12 O 40 ]3− (PW12) can be homogeneously distributed throughout the pores of activated carbon (AC) in organic solvents such as N,N'-dimethylformamide (DMF) and demonstrate the use of this hybrid electrode material in an organic electrolyte (1 M TEABF4 in acetonitrile) supercapacitor. Our results show the efficient electroactivity of the PW12 cluster even in the absence of protons, providing a higher voltage than aqueous electrolytes and fast and reversible redox activity. The hybrid material shows a combination of double-layer (AC) and redox (PW12) capacities leading to an increase (36%) in volumetric capacitance with respect to pristine AC in the same organic electrolyte (1 M TEABF4 in acetonitrile). Remarkably, we were able to quantify this increase as coming predominantly from non-diffusion-limited processes thanks to the utterly dispersed nature of POMs. Moreover, the hybrid material delivers a good rate capability and excellent cycle stability (93% retention of the initial capacitance after 10,000 cycles). This study has a profound significance on improving capacitance of carbon-based materials in organic electrolytes. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Three dimensional carbon materials with hirerarchically porous structure could exhibit superior energy storage performance than two dimensional stacked carbon nanosheet materials. In this work, we prepared a novel ZIF-8-derived nitrogen doped carbon nanoparticles/graphitic carbon nitride composite electrode material with high electrochemical energy storage performances, including high specific capacitances (495 F g −1 at 0.1 A g −1 and 188 F g −1 at 20 A g −1 ) and a stable cycling durability with no capacitance declination after 5000 charge-discharge cycles in three-electrode system. When assembled as electrode materials in symmetrical two-electrode system, the as-prepared composite electrode material could exhibit high specific capacitances of 349.7 F g −1 at 0.5 A g −1 and 261.2 F g −1 at 5 A g −1 . Accordingly, a high energy density of 11.89 Wh/kg can be achieved at the power density of 247.40 W kg −1 . The improvement stems from its hierarchically porous structure with dominant pore sizes at 3 nm and among 4–40 nm, as well as high exposed pyridinic nitrogen (8.58 at%) and pyrrolic nitrogen (3.59 at%) active sites caused by the insertion of ZIF-8-derived nitrogen doped carbon nanoparticles between g-CN layers. This study has provided a new idea on the design of graphitic carbon nitride nanostructures with improved doping level and hiearchically porous structure. [ABSTRACT FROM AUTHOR]

A series of porous carbons (PCs) were obtained from Shengli lignite (SL) via hydrothermal carbonization (HTC) pre-treatment and followed by chemical activation with KOH. The effects of preparation parameters including HTC temperature, KOH-hydrochar ratio and activation temperature on pore structure and the electrochemical performances of PCs were investigated in details. The PCs are mainly micropores structure according to the N 2 adsorption-desorption isotherms test and the highest specific surface area (SSA) is up to 3162 m 2 g −1 . The SSA and total pore volume of PCs with HTC pre-treatment are larger than that without HTC treatment. The electrochemical performances of the symmetric electric double layer capacitor (EDLC) fabricated from these PC electrodes were tested by galvanostatic charge-discharge, cyclic voltammetry and electrochemical impedance spectroscopy. All the PCs as electrode for EDLC exhibit ideal capacitive behaviors in 6 M KOH electrolyte. The specific capacitance of 200-HTC-800-3 can reach as high as 295 F g −1 at the current density of 40 mA g −1 and still retained 210 F g −1 at the current density of 10 A g −1 . It also shows excellent electrochemical cycle performance that after 15000 cycles the specific capacitance value almost not decay. The processes used to produce the PCs can reduce the energy consumption compared to the traditional carbonization-activation method. [ABSTRACT FROM AUTHOR]

Two dimensional heteroatoms-doped graphitic carbon electrode materials could exhibit better capacitive properties than undoped carbon materials. However, since the configuration and the content of the heteroatoms as well as their porous structure are difficult to control, the improvement of their energy storage performance is limited. Here, we report a hierarchically porous boron-doped graphitic carbon nitride nanosheet electrode material with high electrochemical energy storage performances, including high specific capacitances at a fast, carbon-like speed (620.0 F g −1 at 0.1 A g −1 and 312.0 F g −1 at 20 A g −1 ), a high energy density of 86.1 Wh kg −1 and a stable cycling durability with no capacitance declination after 2500 charge-discharge cycles. The improvement stems from the hierarchically porous structure with dominant pore sizes among 1–3 nm, increased pyrrolic nitrogen (11.12 at%) and boron (8.21 at%) active sites due to the addition of ionic liquid. This study has provided a new idea on improving the doping level and porous structure of the electrode material by using ionic liquid as both the heteroatoms source and pore template. [ABSTRACT FROM AUTHOR]

The co-control strategy of doping and vacancy has proved to be an effective and flexible approach in the development of efficient catalysts because of the synergistic regulation of electronic structure and active site number. Here, we synthesized an electrocatalyst with a special micromorphology of succulent plants. In addition, the doping of the rare earth element Ce with a large ionic radius in NiFe bimetallic sulfides is accompanied by a large number of vacancies. Ion doping synergistic with vacancy engineering improves the electrochemical intrinsic performance in the OER process and has enhanced electron transfer ability and electrochemical specific surface area, thus exhibiting high electrocatalytic OER performance, small Tafel slopes, ultralow overpotential of 294 mV at 100 mA cm−2 and 276 mV at 50 mA cm−2 and robust operating durability. Combined with DFT calculations, the role of Ce ions in the NiFe bimetallic sulfide system was revealed. This work not only provides a strategy for designing ion doping to enhance vacancy concentration but also constructs an efficient and stable oxygen evolution electrocatalyst system, which provides an alternative path for designing efficient electric and photocatalysts. [ABSTRACT FROM AUTHOR]

Currently, most of CuS counter electrodes (CEs) used in quantum dot-sensitized solar cells (QDSSCs) are provided with a thickness of hundreds of nanometers or even several microns. Considering the CE with low thickness having many advantages, thin CuS films with thickness ranging from 47 nm below to 115 nm have been synthetized in this paper via chemical bath deposition (CBD) method with different bath concentrations. A power conversion efficiency (PCE) of 3.25% has been achieved utilizing CuS thin films a thickness of only 64 nm as CEs in QDSSCs without any structural optimization, which is higher than the value of the cell employing CuS CE with thickness of 2.8 μm. Electrochemical impedance spectroscopy, Tafel polarization, and two-point current-voltage measurements are used to investigate the electrocatalytic and conductive performance of CuS CEs with different thickness. Owing to the highest electrocatalytic capacity and good conductivity of the 64 nm-thick CuS CE, QDSSC assembled with this CE has reached relatively high PCE under one sun illumination (100 mW cm −2 , AM 1.5). In addition, cyclic voltammetry measurements indicate that the thin CuS CE has a good stability against the polysulfide electrolyte. [ABSTRACT FROM AUTHOR]

A series of stable quasi-solid-state dye-sensitized solar cells (QS-DSSCs) are prepared by the 12-hydroxystearicacid as low molecular mass organogelator (LMOG) to gelate the ionic liquid with different alkyl chain lengths (3, 4, and 7). The influence of alkyl chain length of imidazolium cations (Im + ) on the kinetic processes of electron transport and recombination are investigated by Electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent spectroscopy/intensity-modulated photovoltage spectroscopy (IMPS/IMVS). It is found that the ionic gel electrolytes (IGEs) with different alkyl chain lengths of Im + can influence the competitive adsorption effects of imidazolium cations (Im + ) and Li + , and further affect the charge diffusion, the electron recombination/transport processes, the shift of TiO 2 conduction band edge and surface states distribution. The IGE with longer alkyl chain length of Im + can prolong the electron recombination lifetime, promote the incidental photon-to-electron conversion efficiency (IPCE) and the short circuit photocurrent density ( J sc ). An excellent QS-DSSC based on the IGE with the longer alkyl chain of Im + gives the highest photoelectric conversion efficiency. Moreover, all the QS-DSSCs based on IGEs exhibit excellent durability without losing their photovoltaic performances during the accelerated thermal and light–soaking test. These results are very important to the researches on the electrochemical mechanism and application of QS-DSSCs based on IGEs. [ABSTRACT FROM AUTHOR]

Vacuum thermal evaporated Cu x S (VTE-Cu x S) film on fluorine-doped tin oxide substrate has been investigated as counter electrode (CE) for quantum dot-sensitized solar cells (QDSCs) with polysulfide electrolyte. The photovoltaic parameters of QDSCs show an obvious dependence on the annealing time of Cu x S film, and the maximum power conversion efficiency of 3.16 ± 0.05% under one sun illumination (100 mW cm −2 , AM 1.5 G) was obtained when the VTE-Cu x S CE was annealed at 270 °C for 300 s (VTE-Cu x S-300s CE). Electrochemical impedance spectroscopy, Tafel polarization, and cyclic voltammetry measurements have been employed to investigate the electrocatalytic activity of VTE-Cu x S-300s CE. The electrocatalytic activity of the VTE-Cu x S-300s CE is much higher than that of Pt CE, and is slightly higher than that of Cu 2 S CE in situ prepared on brass sheet. In particular, VTE-Cu x S-300s CE holds high diffusion velocity of S 2− /S n 2− in polysulfide electrolyte, and the stability of its electrocatalytic activity in polysulfide electrolyte is better than that of Pt and Brass-Cu 2 S CEs obviously. [ABSTRACT FROM AUTHOR]

Abstract: The Cu2ZnSnS4 (CZTS) thin films with uniform and porous surface feature with the pore size of 100-200nm were successfully prepared by pyrolysis procedure using the methanol solution containing copper chloride dihydrate (0.06mol dm−3), zinc chloride (0.03mol dm−3), stannous chloride dihydrate (0.03mol dm−3), thiourea (0.48mol dm−3) and deionized water (1.92mol dm−3) as precursor solution at 380°C in air atmosphere. Electrochemical impedance spectroscopy was applied to evaluate the electrochemical catalytic activity of the pyrolysis CZTS thin films for redox couple of Sn 2-/S2− and the charge transfer resistance was 64.08Ω using the pyrolysis CZTS thin film obtained by repeating the procedure of dipping the FTO substrate into the precursor solution and heating at 380°C for 7 cycles. The assembled quantum dot-sensitized solar cells gave an open-circuit photovoltage of 0.52V, a short-circuit photocurrent density of 12.96mAcm−2, and a fill factor of 0.38, corresponding to the photoelectric conversion efficiency of 2.56%. Because the pyrolysis procedure was a facile, low cost and vacuum-free process, and had the advantage of obtaining various porous microstructure thin films and allowing deposition over large areas, the pyrolysis CZTS thin films can serve as an effective counter electrode for QDSCs. [Copyright &y& Elsevier]

Abstract: Three-dimensional (3D) porous V2O5 and Fe0.1V2O5.15 thin films have been prepared by electrostatic spray deposition technique. X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy are employed to investigate the structures and valence states of the films. Galvanostatic cell cycling, cyclic voltammetry and impedance spectroscopy are used to characterize their electrochemical properties. The Fe0.1V2O5.15 thin film shows much better cycling performance than the non-doped V2O5 thin film. Fe3+ can act as a stabilizing agent in the layered V2O5 and increase the reversibility of the charge and discharge processes towards deeper depth of lithium insertion/extraction. The dissolution of the active material in the electrolyte can also be significantly suppressed in the Fe-doped sample. Nevertheless, the Fe-doping causes a slight decrease in lithium ion diffusion coefficient. [Copyright &y& Elsevier]

Abstract: Poly(diallyldimethylammonium chloride) functionalized helical carbon nanotubes (PDDA-HCNTs) were successfully synthesized. The resulting PDDA-HCNTs composite has good conductivity, solubility and ferromagnetic property. The fabricated HCNTs could be conveniently separated and magnetically attached to the magnetic electrode owing to their excellent magnetic properties. An amperometric biosensor was firstly developed based on glucose oxidase (GOD) functionalized PDDA-HCNTs loaded on magnetic glass carbon electrode. The constructed biosensor exhibited excellent electrocatalytic activity and stability for the detection of glucose with a linear range from 5 to 85μM and a low detection limit of 0.72μM at 3σ. The present work offers a new avenue to broaden the applications of HCNTs in electrochemical biosensors. [Copyright &y& Elsevier]

Herein, a facile top-down approach and a post-synthetic etching strategy were reported to prepare high-quality sulfur quantum dots (H-SQDs), which were first discovered with a boosted anodic electrochemiluminescence (ECL) emission in an aqueous solution. Elaborate investigations demonstrated that the significantly improved ECL properties of H-SQDs were attributed to the reduced size for inherent brightness, the highly passivated surface, and enhanced charge injection/transfer capacities after the post-synthetic hydrogen peroxide etching. The underlying anodic ECL mechanism and the redox nature of H-SQDs were studied in detail for the first time, indicating a direct oxidation ECL mechanism with tri-n-propylamine as the "oxidation-reduction" coreactant. Beyond that, the as-obtained H-SQDs also featured low cost, remarkable monodispersity, excellent water-solubility, and good biocompatibility, illustrating their great potential in ECL bioanalysis. As a proof-of-concept, H-SQDs, an emerging ECL emitter with high ECL efficiency, was utilized to construct an "off-on" ECL biosensor for sensitive glutathione (GSH) assay. This work not only promotes the exploration of novel ECL emitters, but also provides a new perspective for the application of SQDs-based ECL biosensor in clinical diagnosis. [ABSTRACT FROM AUTHOR]

• A novel PbO 2 /Y 2 O 3 nano-composite anode with hybrid interfaces was prepared. • Incorporating Y 2 O 3 optimized the crystal size and adsorbed oxygen of PbO 2. • Obtained the significantly improved degradation efficiency to malachite green. • The electrocatalytic degradation mechanism of PbO 2 /Y 2 O 3 anode was revealed. Underlying the electrocatalytic mechanism has profound influences on designing novel efficient electrocatalytic interfaces and improving the efficiency of electrocatalytic degradation. In this study, a novel PbO 2 /Y 2 O 3 nano-composite anode with hybrid interface was successfully prepared to investigate the electrocatalytic oxidation of malachite green (MG). The comprehensively analyzed XRD and XPS results confirmed that the partial incorporation of Y 2 O 3 nanoparticles reduced the crystal size of PbO 2 and increased the adsorption of hydroxyl oxygen (O ads). The bipotential step chronoamperometry (BSCP) curve suggested that PbO 2 /Y 2 O 3 anode possessed larger diffusion coefficients (D) and catalytic rate constants (K cat). In addition, the incorporated Y 2 O 3 nanoparticles promoted the electrocatalytic activity at the anode interface and enhanced the electron transfer as well as accelerated the generation of reactive oxygen species (ROS), which afford the PbO 2 /Y 2 O 3 anode high removal efficiency of MG and total organic carbon (TOC) with low energy consumption under the optimum conditions. Moreover, the electrocatalytic degradation mechanism and possible electrocatalytic mineralization pathway of MG on PbO 2 /Y 2 O 3 anode were also discussed in detail, which provides a reference for the material science and environmental governance in the future. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Sn-based materials as potential anode materials have triggered significant research interests for lithium storage owing to their high theoretical capacity and low cost. However, the practical applications of Sn-based materials are hindered by low capacity release and fast capacity fading due to large volume expansion and structural pulverization of the electrodes during cycling. Herein, we demonstrate an efficient strategy to alleviate/resolve the above issues by introducing highly conductive inactive metal to alloy with Sn and then loading the Sn-based alloy particles onto two-dimensional (2D) graphene matrix. The graphene supported Fe–Sn nanoalloy composites (FeSn 2 /FeSn/Fe-rGO) are synthesized via a facile bimetallic metal-organic framework precursor route, in which Sn 3 [Fe(CN) 6 ] 4 nanocubes are grown in-situ on reduced graphene oxide (rGO) sheets, followed by thermal decomposition of the Sn 3 [Fe(CN) 6 ] 4 /rGO precursor in an Ar/H 2 atmosphere. As a result, the lithium-ion batteries based on FeSn 2 /FeSn/Fe-rGO composites exhibit outstanding lithium storage performance with a remarkable reversible capacity of 1274 mAh g−1 at 0.2 A g−1 after 200 cycles, a great rate capability of 665 mAh g−1 at 5.0 A g−1, and excellent high-rate cycling stability with a capacity decay of only 0.025% per cycle within 1200 cycles at 2.0 A g−1. The excellent electrochemical performance of FeSn 2 /FeSn/Fe-rGO can be ascribed to its unique three-order buffer structures: the Fe atoms in FeSn 2 and FeSn acting as tough buffer, metal Fe as framework buffer for cubic nanoparticles, and rGO as 2D elastic matrix buffer, which effectively alleviate the volume expansion and structural pulverization of the electrode during lithiation, synergistically enhance the lithium storage performance. Image 1 • Graphene supported Fe-Sn nanoalloy composites were prepared via a facile metal-organic framework precursor route. • The FeSn 2 /FeSn/Fe-rGO anode exhibits high reversible capacities, great rate capability, and excellent cycle stability. • Fe species in the composites effectively alleviated the volume expansion and structural pulverization of the electrode. • The graphene matrix accommodated the large volume change and prevented Fe–Sn alloy particles aggregation. [ABSTRACT FROM AUTHOR]