•Bi4O5Br2 nanoflakes with a thickness of approximately 5 nm are synthesized by a rapid and energy saving microwave route.•Bi4O5Br2 nanoflakes show excellent conversion efficiency (>99%) and selectivity (>99%) toward photocatalytic oxidation of BA into BAD under blue LED.•A possible mechanism of selective photocatalytic oxidation with high selectivity and conversion ratio is proposed based on experimental results and DFT calculations.Novel Bi4O5Br2 nanoflakes with a thickness of approximately 5 nm and a band gap energy of 2.54 eV were synthesized by a rapid and energy-saving microwave route. Under blue light emitting diode (LED) irradiation and using the Bi4O5Br2 nanoflakes as a photocatalyst, selective catalytic oxidation of benzyl alcohol (BA) into benzaldehyde (BAD) was successfully achieved with a high selectivity and conversion ratio. Compared to Bi12O17Cl2, which has a similar blue LED light absorption capability and a band gap energy of 2.37 eV, these Bi4O5Br2 nanoflakes exhibit superb conversion efficiency (>99%) and selectivity (>99%) toward the photocatalytic oxidation of BA into BAD. Based on the structural characterization of the as-synthesized photocatalyst, comparison of photocatalytic performances, investigation of active radicals, and quantum chemical calculations, a possible photoreaction pathway is explored and proposed. It is revealed that the high selectivity of the system comes from direct hole oxidation of alkoxide anions (BA−) and the appropriate valence band potential (+2.41 V vs. NHE) of Bi4O5Br2. And the high conversion ratio is attributed to the positively charged surface, large specific surface area with micro-nano structures, and effective separation of photogenerated carriers of the as-synthesized photocatalyst. In addition, the as-synthesized Bi4O5Br2 catalyst remains stable during the photocatalytic conversion process and can be utilized repeatedly, suggesting its potential for practical applications.Download high-res image (200KB)Download full-size image

•Li1.2Mn0.54Ni0.13Co0.13O2/graphite battery with DPDS as additive is evaluated.•DPDS was oxidized and reduced prior to the solvent to form SEI films.•DPDS help improve the high-temperature performance of lithium ion batteries.The effect of diphenyl disulfide (DPDS) as a bifunctional additive on the performance of Li1.2Mn0.54Ni0.13Co0.13O2/graphite batteries cycled at elevated temperature was evaluated. The batteries with 1.0 wt.% DPDS exhibited a capacity retention of 68.4% after 100 cycles under 55 °C, which was higher than that without DPDS (44.4%). In addition, the self-discharge of the Li1.2Mn0.54Ni0.13Co0.13O2/graphite battery was also suppressed in a storage test at 85 °C for 8 h by adding 1.0 wt.% DPDS in the electrolyte. Linear sweep voltammetry and cyclic voltammetry combined with density functional theory calculations indicated that DPDS was oxidized and reduced prior to the solvent to participate in the formation of solid electrolyte interface (SEI) films on the cathode and anode simultaneously. The alternating current impedance and X-ray diffraction suggest that the SEI films derived from DPDS are helpful for enhancing the interface performance of the electrodes and protecting the Li1.2Mn0.54Ni0.13Co0.13O2 and graphite structures from deterioration during high-temperature cycling, which is responsible for the improvement in the performance of the Li1.2Mn0.54Ni0.13Co0.13O2/graphite batteries at elevated temperature.

As lithium-ion batteries (LIBs) find application in new fields, the specific capacity of single LIBs must be enhanced, and the backward-cell problem in battery modules must be solved. Here, Mn3O4 and carbon nanofragment (Mn3O4/CNF) composites are synthesized and shown to have higher capacities than commercial graphite (theoretical capacity of approximately 372 mAh·g−1) and hierarchical voltage plateaus. Nanosized Mn3O4 particles are introduced into the CNFs to simultaneously increase the specific capacity and prevent the corresponding LIB modules from over-discharging. The Mn2+-modified CNFs are spray-dried and calcined to form Mn3O4/CNF composites with 1.62%, 3.21%, and 6.74% Mn, which exhibit enhanced reversible specific capacities of 486.1, 609.3, and 539.0 mAh·g−1, respectively, at 0.1C after 100 cycles. Furthermore, the additional voltage plateau at 1.2 V due to Mn3O4 can help prevent the corresponding LIB modules from over-discharging and metallic lithium deposition on the anode.Download high-res image (142KB)Download full-size image

•Self-supported PVdF/P(VC-VAc) blended polymer membranes are prepared.•Membranes with rich porous structure can be acquired via the phase inversion method.•The blended polymer electrolytes exhibit superior compatibility with electrodes.•This electrolyte has promising applications in high-voltage lithium ion batteries.New self-supported poly(vinylidene fluoride)/poly (vinyl chloride-co-vinyl acetate) (PVdF/P(VC-VAc)) blended polymer membranes are prepared via a phase inversion method, and then their electrochemical performances, immersed in the liquid electrolyte as the polymer electrolyte for lithium-ion batteries (LIBs), are evaluated. The Fourier transform infrared spectroscopy analysis, the differential scanning calorimeter test and the X-ray diffraction measurement demonstrate that homogeneous PVdF/P(VC-VAc) polymer composites can form at all blend compositions and the crystallinity degree of the blended polymers decreases as the P(VC-VAc) content increases. Specifically, when the proportion of PVdF/P(VC-VAc) is 70:30 (wt%), membranes with a rich surface and internal porous structure can be acquired. The ionic conductivity of the polymer electrolyte achieves a maximum value of 3.57 mS cm−1 at room temperature, and favourable electrochemical performances of LIBs can be obtained. LiNi0.5Mn1.5O4/Li cells with the as-prepared polymer electrolyte exhibit a higher initial discharge capacity of 131.0 mAh g−1 and superior cycle stability with a capacity retention of 96.1% at 0.2 C after 200 cycles compared to cells based on pure PVdF and P(VC-VAc) membranes. This can be attributed to the superior compatibility of the electrolyte with the electrodes. The results also indicate this electrolyte has promising applications in high-voltage LIBs.Download high-res image (288KB)Download full-size image

A reconstructed graphite-like carbon (r-GC) micro/nano-structure with a higher capacity than and a comparative voltage plateau to commercial graphite anodes of lithium-ion batteries (LIBs) is synthesized from an expandable graphite raw material based on an up-down-up synthetic strategy. The expandable graphite powders are thermally expanded, hydrothermally cut, and ultrasonically crushed in turn to prepare a suspension containing nano-fragments with a graphitic plane nano-structure as a carbon precursor. Then, the r-GC micro/nano-structure can be obtained by stacking the graphite nano-fragments through spray drying the suspension and subsequently conducting a calcining treatment. This r-GC exhibits an initial capacity of 575.3 mA h g−1 at 0.1C and a reversible capacity of 508.4 mA h g−1 after 100 cycles. Especially, its comparative voltage plateau of commercial graphite is incapable for other known anode materials for LIBs. In the potential window of 0.3–0.01 V (vs. Li+/Li), a maximum capacity of approximately 432.1 mA h g−1, 1.16 times the theoretical capacity of graphite (372 mA h g−1), is obtained. The unique element stability, capacity, and voltage plateau indicate that the as-synthesized r-GC is a promising sheet-like anode material for LIBs. In addition, an embedded-defect and graphite-dominant graphite/graphene cooperative lithiation mechanism is proposed to elaborate the capacity and voltage plateau of r-GC.

•Diphenyl disulfide is evaluated as a new bifunctional electrolyte additive.•DPDS can improve the high-voltage performance of LiCoO2/graphite batteries.•The films induced by DPDS can be formed on the two electrodes at higher potentials.•These films can provide effective protection for the LiCoO2 and graphite materials.Diphenyl disulfide (DPDS) is evaluated as a new bifunctional electrolyte additive to improve the high-voltage performance of LiCoO2/graphite batteries. With the addition of DPDS in the electrolyte, the cell with 2.0 wt% DPDS exhibits enhanced performance in the normal voltage range of 3.0 V–4.2 V. In particular, when the cut-off potential is increased from 4.2 V to 4.4 V, the cell with 1.0 wt% DPDS also exhibits improved discharge capacity and cycle performance. Linear sweep voltammetry and cyclic voltammetry indicate that the DPDS can be reduced prior to the solvent and that the oxidative decomposition of the electrolyte can also be suppressed. In addition, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy analyses demonstrate that the solid electrolyte interface (SEI) film is produced primarily on the graphite anode via the decomposition of DPDS at normal voltage and that the SEI films induced by DPDS can be formed simultaneously on the two electrodes at higher potentials. It is hypothesized that these compact SEI films covering the electrode surface provide protection for the LiCoO2 and graphite materials and accordingly improve the cyclic performance of battery in the voltage range of 3.0 V–4.4 V.

•1H,1H,5H-Perfluoropentyl-1,1,2,2-tetrafluoroethylether is evaluated as a co-solvent.•F-EAE improves the oxidation stability of the electrolyte at high voltage.•F-EAE facilitates the formation of a passivation interphase on the graphite anode.•Use Three-electrode pouch cells in tracking the impedance changes of each electrodes.1H,1H,5H-Perfluoropentyl-1,1,2,2-tetrafluoroethylether (F-EAE) mixed with ethylene carbonate (EC), diethyl carbonate (DEC), and lithium hexafluorophosphate (LiPF6) is evaluated as a co-solvent high-potential electrolyte of LiNi1/3Co1/3Mn1/3O2/graphite batteries. Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) indicate that the EC/DEC-based electrolyte with F-EAE possesses a high oxidation potential (>5.2 V vs. Li/Li+) and excellent film-forming characteristics. With 40 wt% F-EAE in the electrolyte, the capacity retention of the LiNi1/3Co1/3Mn1/3O2/graphite pouch cells that are cycled between 3.0 and 4.5 V is significantly improved from 28.8% to 86.8% after 100 cycles. In addition, electrochemical impedance spectroscopy (EIS) of three-electrode pouch cells, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) are used to characterize the effects of F-EAE on the enhanced capacity retention. It is demonstrated that F-EAE facilitates the formation of a stable surface electrolyte interface (SEI) layer with low impedance on the anode and effectively suppresses an increase in the charge-transfer resistance on the cathode. These results suggest that F-EAE can serve as an alternative electrolyte solvent for 4.5 V high voltage rechargeable lithium-ion batteries.

A composite separator is prepared to improve the safety of lithium ion batteries (LIBs) based on a gravure coating aqueous slurry and post-hot-pressing method. An environmentally friendly aqueous slurry with an Al2O3 ceramic holder and polyvinylidene difluoride-hexafluoropropylene (PVdF-HFP) and carboxymethyl cellulose (CMC) dual-binders is coated on a polyolefin (PE) substrate to form a prototype Al-PHC/PE separator. Then, after assembling the separator in the batteries and hot-pressing at 70 °C and 0.8 MPa for 3 h, the granular PVdF-HFP is transformed into a colloidal structure containing an electrolyte, which can binds the Al2O3 nanoparticles together and increases the battery hardness. Compared with a PE separator (9 μm), the Al-PHC/PE-2 separator (12 μm, with a Al2O3/PVdF-HFP weight ratio of 7/3) displays a comparative ionic conductivity of 9.3 × 10−4 S cm−2 and exhibits no obvious thermal deformation at 110 °C for 60 min. All of the batteries assembled with Al-PHC/PE-2 separators passed nail penetration and impact tests. In addition, the capacity retention increases from 83.4% to 87.6% when the battery is assembled with Al-PHC/PE-2 instead of a PE separator and charge-discharged at 0.7C/1.0C for 350 cycles. The enhanced safety and cycle performance indicate the promising prospect of Al-PHC/PE separators in LIBs.

Nonstoichiometric bismuth oxyiodide materials have exhibited high potential for applications in visible-light photocatalytic environmental cleaning and solar energy conversion. Herein, novel Bi4O5I2/Bi5O7I nanocomposites, BiOI nanosheets, Bi4O5I2 nanoflowers, and Bi5O7I microfibers are synthesized by controlling the alkalinity of reaction solutions in a facile one-pot hydrothermal route. The as-prepared Bi4O5I2/Bi5O7I nanocomposite exhibits excellent visible-light photocatalytic performance for the degradation of propylparaben (PPB, a potential environmental contaminant structure that contains a benzene ring, hydroxyl, and carboxyl), which is approximately 32, 33, and 4 times higher than that of pure BiOI, Bi5O7I, and Bi4O5I2, respectively. The enhanced photocatalytic activity of the Bi4O5I2/Bi5O7I composite can be attributed to enhancement of charge separation by the formation of Bi4O5I2/Bi5O7I interfaces, more positive valence band edge potential at +2.18 V, good absorption from UV to visible light, three-dimensional flower-like morphology composed of number nanoflakes, and large specific surface area with mesoporous features. The band structures of Bi4O5I2 and Bi5O7I, the electrochemical oxidation behaviors of PPB, and the roles of the primary photogenerated oxidative species are analyzed, then a reasonable photocatalytic mechanism is proposed based on the experimental results. In addition, the as-synthesized Bi4O5I2/Bi5O7I heterojunction remains stable throughout photocatalytic process and can be used repeatedly, indicating its potential for practical applications.

The electrochemical behaviors and simultaneous determination of three dihydroxybenzene isomers, i.e., catechol (CC), resorcinol (RC), and hydroquinone (HQ), are studied using a thermally reduced carbon nano-fragment modified glassy carbon electrode (CNF/GCE). The soluble CNF modifier with unique micro-/nano-structure and abundant edges and defective sites is prepared by chemically oxidizing graphite powders, ultrasonically crushing, and thermally reducing treatment in turn. It is shown that the oxidation peak currents of CC, RC, and HQ at the CNF/GCE are improved about 1.74, 2.88, and 1.05 times compared to that of the GCE. The diffusion process in bulk solution controls the electrochemical reaction of CC, RC, and HQ, and their reversible electrochemical process involves equal numbers of protons and electrons. Based on the enhanced electrocatalytic activity and enlarged separation of the anodic peak potential towards three dihydroxybenzene isomers at the CNF/GCE, the simultaneous differential pulse voltammetry (DPV) determination of CC, RC, and HQ, with detection limits (S/N = 3) of 5.0 × 10−7 mol L−1, 8.0 × 10−7 mol L−1 and 4.0 × 10−7 mol L−1, respectively, are obtained. The CNF/GCE also indicates high selectivity, stability, and reproducibility, and is comparable with results of high-performance liquid chromatography in real samples, clearly indicating its applicability.

The preparation of polyethylene-supported poly(vinylidene fluoride)/cellulose acetate butyrate/nano-SiO2 particle (PVDF-CAB-SiO2/PE) blended gel polymer electrolytes (GPEs) is reported here. The electrolyte uptake, mechanical properties, thermal stability, and electrochemical performance of these electrolytes are characterized to evaluate their potential application in lithium-ion batteries (LIBs). The results indicate that the particle size of SiO2 can be adjusted by the tetraethyl orthosilicate (TEOS) concentration and affects the physicochemical properties of the membrane. By doping 5 wt.% SiO2 (500 nm) into the PVdF-CAB blended polymer, the porosity of the membrane increases from 40 to 42.3 %, the mechanical strength from 117.3 to 138.7 MPa, the electrolyte uptake from 149 to 195 %, the oxidation decomposition potential from 4.7 to 5.2 V, and the ionic conductivity of the corresponding GPE is improved from 1.16 to 2.98 mS cm−1 at ambient temperature. The PVDF-CAB-SiO2/PE-based GPE and the two electrodes are suitably compatible, and the thermal stability is higher than that of the polyethylene (PE) membrane. The LIBs with the as-prepared GPE also exhibit enhanced discharge capacity and cycle stability, indicating the promising application of these GPEs in LIBs.

Large-scale synthesis of nanosized β-Bi2O3 is a significant challenge due to its metastable state. A facile L-asparagine-assisted reflux–calcination route was successfully developed for the large-scale preparation of β-Bi2O3 micro/nanostructures under mild conditions (low temperature, atmospheric pressure, and wide temperature windows). The composition, phase structure, morphology, surface area, and photoabsorption properties of as-synthesized β-Bi2O3 and its precursor were systematically characterized. The phase transformation conditions and possible formation mechanism of flower-like β-Bi2O3 were discussed. It is found that with a simple reflux process under atmospheric pressure at 100 °C, uniform monodisperse bismuth–asparagine complex microspheres with average diameters of ∼500 nm were produced and flower-like β-Bi2O3 micro/nanostructures were then conveniently obtained after precursor calcination at temperatures ranging from 340 °C to 420 °C. A surface CO32− coordination effect introduced from L-asparagine explained the formation of stabilized β-Bi2O3 at low temperatures (up to 420 °C). The as-synthesized β-Bi2O3 shows excellent photocatalytic activity toward the degradation of 4-phenylphenol under visible-light irradiation, which is 3.7 and 21.4 times faster than the removal rates of β-Bi2O3 nanospheres and a commercial β-Bi2O3, respectively, and allows for the elimination of 93.2% total organic carbon after 60 min of irradiation. In addition, the photogenerated reactive species were identified by radical scavenger experiments and electron paramagnetic resonance spectroscopy, and a possible visible-light-induced photocatalytic mechanism was then proposed.

β-Bi2O3 micro/nanostructures with tunable morphologies were synthesized via a one-pot solvothermal–calcining route, and their photocatalytic activity toward degrading methylparaben (MeP, a widely used preservative with estrogenic activity) was evaluated under visible-light (λ ≥ 420 nm) irradiation. The formation process of β-Bi2O3 catalysts can be described as reduction of Bi3+ through a solvothermal reaction, followed by oxidization of metal Bi via calcination in air. During this process, the organic reductants (single or a mixture of ethylene glycol, D-fructose, and ascorbic acid) play important roles in determining the final morphologies and structures of the materials. Photocatalytic tests reveal that MeP can be effectively degraded and mineralized by using synthetic β-Bi2O3 catalysts, and the reaction rate constant of an optimum sample is more than 25 and 160 times faster than a commercial Bi2O3 and synthetic N-TiO2, respectively. The superior photocatalytic activity of the optimum product is ascribed to its pure beta phase with a narrower band gap, good absorption of visible light, more efficient separation of electrons and holes, relatively higher BET specific surface area, and three-dimensional architectures, which favor more surface active sites and easier mass and photoinduced charge transportations. In addition, the main reactive oxygen species and possible degradation intermediates were detected, and the results suggest that photogenerated holes and superoxide radicals are the predominant species in the photochemical oxidation process.

A novel graphene-based nanomaterial, multi-nanopore graphene (mp-GR), modified glassy carbon electrode (mp-GR/GCE) is prepared for the simultaneous determination of dopamine (DA) and uric acid (UA) in the presence of ascorbic acid (AA). After a hydrothermal reaction of the graphene oxide in the presence of H2O2 at 180 °C for 2 h, the water-soluble mp-GR is obtained from the hydrothermal suspension. This mp-GR exhibits abundant carboxylic and/or hydroxide groups, edges, and defective sites due to the reaction and structure disruption caused by the hydrothermal treatment. The mp-GR appears an enhanced electrocatalytic activity toward DA and UA due to the unique structure and composition. The oxidation peak current of DA at the mp-GR/GCE is about 2.70 and 8.61 times higher than at the GR/GCE and the GCE, respectively. Using the mp-GR/GCE, the simultaneous differential pulse voltammetry determination of DA and UA in the presence of AA is successfully carried out, the detection limits (S/N = 3) for DA and UA are 1.5 × 10−6 mol L−1 and 2.0 × 10−6 mol L−1, respectively. In addition, this mp-GR/GCE exhibits high selectivity, reproducibility, and stability, and also can detect DA and UA in real human blood serum, showing its promising application in the electroanalysis of real samples.

•Nitrogen-doped graphene quantum dots (N-GQDs) are prepared by hydrothermal routine.•Two N-GQDs with different size distribution emit green/khaki photoluminescence.•Two N-GQDs exhibit excitation-dependent/independent photoluminescence behaviors.A simple and effective chemical synthesis of the photoluminescent nitrogen-doped graphene quantum dots (N-GQDs) biomaterial is reported. Using the hydrothermal treatment of graphene oxide (GO) in the presence of hydrogen peroxide (H2O2) and ammonia, the N-GQDs are synthesized through H2O2 exfoliating the GO into nanocrystals with lateral dimensions and ammonia passivating the generated active surface. Then, after a dialytic separation, two water-soluble N-GQDs with average size of about 2.1 nm/6.2 nm, which emit green/khaki luminescence and exhibit excitation dependent/independent photoluminescence (PL) behaviors, are obtained. In addition, it is also demonstrated that these two N-GQDs are stable over a broad pH range and have the upconversion PL property, showing this approach provides a simple and effective method to synthesize the functional N-GQDs.

This study demonstrates that tris(trimethylsilyl)borate (TMSB) additive in the electrolyte can dramatically improve the cycling performance of LiNi0.5Co0.2Mn0.3O2/graphite cell at higher voltage operation. And the effects of this additive are characterized by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). In the voltage range of 3.0–4.4 V, LiNi0.5Co0.2Mn0.3O2/graphite cell with TMSB in the electrolyte retains about 92.3% of its initial capacity compared to the cell without additive in the electrolyte that retains only 28.5% of its initial capacity after 150 cycles, showing the promising prospect of TMSB at higher voltage. The enhanced cycling performance is attributed to the thinner film originated from TMSB on the LiNi0.5Co0.2Mn0.3O2 and the combination of TMSB with PF6− and F− in the electrolyte, which not only protects the undesirable decomposition of EC solvents but also results in lower interfacial impedance.Highlights► TMSB is evaluated as an electrolyte additive in LiNi0.5Co0.2Mn0.3O2 based cell at high voltage. ► A thinner cathode electrolyte interface can be formed using TMSB in the electrolyte. ► The combination of TMSB with anion can lower the interfacial impedance. ► The cycle performance of LIBs (3.0–4.4 V) can be improved using this additive.

•The GR-DNA/GCE exhibit high electrocatalytic oxidation activity to NP.•The DPV determination of NP is achieved using GR-DNA/GCE.•The GR-DNA/GCE is used to determine the NP in real samples.The electrochemical determination of nonylphenol (NP) using differential pulse voltammetry (DPV) is developed based on a reduced graphene–DNA hybrid-modified glassy carbon electrode (GR-DNA/GCE). The electrochemical oxidation of NP at the GR-DNA/GCE is shown to be an one-electron and one-proton process, and due to the synergic effect of GR and DNA, the GR-DNA/GCE has 4.87, 2.76 and 2.09 times higher current response than bare GCE, DNA/GCE, and GR/GCE, respectively. Using DPV in the 0.1 mol L−1 acetate buffer solution at 0.1 V and with a 300 s accumulation time (pH = 4.6), the GR-DNA/GCE exhibits a linear current response towards the electrochemical oxidation of NP in the concentration range of 5.0 × 10−8 to 4.0 × 10−6 mol L−1 and a detection limit of 1.0 × 10−8 mol L−1 (S/N = 3). In addition, this GR-DNA/GCE also indicates high selectivity and reproducibility, and can be successfully used to determine the presence of NP in Asian Clams and natural water samples with comparative sensitivity to high-performance liquid chromatography, and with recoveries ranging from 95% to 103%, showing its practical prospects in the determination of NP in real samples.

In this paper, the electrochemical oxidation and differential pulse voltammetry (DPV) determination of catechol (CC) and hydroquinone (HQ) are studied at a novel carbon nano-fragment (CNF) modified glassy carbon electrode (CNF/GCE). The CNF modifier is prepared using the graphite cycled in lithium-ion batteries as the raw material through a ball mill process. The redox reactions of CC and HQ at the CNF/GCE are a two proton and electron process and controlled by the diffusion step. Compared to the GCE, the as-prepared CNF/GCE shows enhanced electrocatalytic activity and a peak potential difference of about 104 mV towards the oxidation of CC and HQ in a 0.1 mol L−1 acetate buffer solution (ABS, pH = 5.9), which makes it suitable for simultaneous determination of CC and HQ by DPV. Under the optimized conditions, the oxidation peak current of CC is linear over a range from 2.0 × 10−6 mol L−1 to 2.0 × 10−4 mol L−1 in the presence of 5.0 × 10−5 mol L−1 HQ with a detection limit of 1.0 × 10−7 mol L−1 (S/N = 3). Correspondingly, the oxidation peak current of HQ is linear over a range from 6.0 × 10−6 mol L−1 to 2.0 × 10−4 mol L−1 in the presence of 5.0 × 10−5 mol L−1 CC with a detection limit of 2.5 × 10−7 mol L−1 (S/N = 3). In addition, this CNF/GCE exhibits high selectivity, reproducibility and stability, showing its promising application prospect.

We have developed a stable and sensitive nonenzymatic glucose sensor by modifying a glassy carbon electrode (GCE) with a composite incorporating nickel(II) oxides and reduced graphene. The oxides were generated by directly electrodepositing nickel on the GCE with a graphene modifier using a multi-potential pulse process, and then oxidizing nickel to nickel(II) oxides by potential cycling. In comparison to the conventional nickel(II) oxides-modified GCE, this new nickel(II) oxides-graphene modified GCE (NiO-GR/GCE) has an about 1.5 times larger current response toward the nonenzymatic oxidation of glucose in alkaline media. The response to glucose is linear in the 20 μM to 4.5 mM concentration range. The limit of detection is 5 μM (at a S/N of 3), and the response time is very short (<3 s). Other beneficial features include selectivity, reproducibility and stability. A comparison was performed on the determination of glucose in commercial red wines by high-performance liquid chromatography (HPLC) and revealed the promising aspects of this sensor with respect to the determination of glucose in real samples.

A series of bismuth oxyhalides with controllable composition and band structure have been successfully synthesized by a facile and general one-pot hydrothermal route using Bi2O3 as the starting material; their band structures and visible-light-induced photocatalytic performances are investigated.

In order to overcome the capacity fading of LiCoO2/graphite Lithium-ion batteries (LIBs) cycled in the voltage range of 3.0–4.5 V (vs. Li/Li+), methylene methanedisulfonate (MMDS) is newly evaluated as an electrolyte additive. The linear sweep voltammetry (LSV) and cyclic voltammetry (CV) indicate that MMDS has a lower oxidation potential in the mixed solvents of ethylene carbonate (EC) and ethyl methyl carbonate (EMC), and participates in the formation process of the cathode electrolyte interface (CEI) film. With the addition of 0.5 wt.% MMDS into the electrolyte, the capacity retention of the LiCoO2/graphite cells cycled in 3.0–4.5 V is significantly increased from 32.0% to 69.6% after 150 cycles, and the rate capacity is also improved compared with the cells without MMDS additive in the electrolyte, showing the promising prospect in the electrolyte. In addition, the results of electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) demonstrate that the enhanced electrochemical performances of the cells can be ascribed to the modification of components of cathodes surface layer in the presence of MMDS, which resulting the suppression of the electrolyte oxidized decomposition and the improvement of CEI conductivity.Highlights► MMDS is newly evaluated as an electrolyte additive. ► This additive tends to be decomposed on LiCoO2 cathode prior to the solvents. ► A highly ionic conductivity film can be formed using MMDS in the electrolyte. ► The cycle performance of LIB (3.0–4.5 V) can be improved using this additive.

The graphene and 5-[o-(4-Bromine amyloxy) phenyl]-10,15,20-triphenylporphrin (o-BrPETPP) composite (GR-o-BrPETPP) film is prepared on the glassy carbon electrode (GCE) with graphene oxide (GO) modifier through a consecutive cyclic voltammetry process, and then its electrocatalytic oxidation to indirubin is investigated. The as-prepared GR-o-BrPETPP film exhibits wrinkling paper-like structure and lower electron transfer resistance. In comparison with the o-BrPETPP/GCE and GCE, the GR-o-BrPETPP film electrode prepared for five cycles indicates an excellent electrocatalytic oxidation activity toward indirubin with about 2.2 and 13.3 times higher current response, respectively. In addition, in the 0.1 mol L−1 acetate buffer solution (pH = 4.6), the film electrode displays a linear relationship between the oxidation current and the indirubin concentration in the range from 5.0 × 10−7 mol L−1 to 2.4 × 10−5 mol L−1, and presents a detection limit of 1.0 × 10−7 mol L−1 (S/N = 3) by differential pulse voltammetry (DPV) with 220 s accumulation. Especially, this film electrode also shows a comparative sensitivity with high-performance liquid chromatography (HPLC) for the determination of the indirubin extractive of herbal medicines, showing its practical prospect in the electrochemical determination of indirubin.Graphical abstractHighlights► The graphene and o-BrPETPP composite film electrode is prepared through a consecutive cyclic voltammetry process. ► The electrocatalytic oxidation of indirubin at the film electrode is investigated. ► The GR-o-BrPETPP film electrode shows a comparative sensitivity with HPLC to the DPV determination of indirubin.

In this paper, the direct electrochemical oxidation and differential pulse voltammetry (DPV) determination of guanine and adenine are studied by using an electrochemically reduced graphene oxide (er-GO) modified glassy carbon electrode (er-GO/GCE). Compared to the GCE and the GO/GCE, the as-prepared er-GO/GCE shows excellent electrocatalytic activity towards guanine and adenine, with an increase of oxidation current along with a negative shift of oxidation potential. Using the as-prepared er-GO/GCE, the simultaneous determination of guanine and adenine is successfully carried out, and the detection limits (based on S/N of 3) for guanine and adenine are 1.5 × 10−7 mol L−1 and 2.0 × 10−7 mol L−1, respectively. In addition, this er-GO/GCE exhibits a high selectivity, reproducibility and stability, and also can be used for the detection of guanine and adenine in the thermally denatured calf thymus DNA and urine, showing its promising application in the analysis of real samples.

A novel electrolyte applied in electrochemical double-layer capacitors (EDLCs) has been prepared based on lithium hexafluorophosphate (LiPF6) and acetamide and subsequently characterized by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), electrochemical techniques and so on. The mixtures of LiPF6 and acetamide at the molar ratios of 1:4 to 1:6 exist as liquids below 25 °C, which is attributed to the melting point depression of mixture and the coordination of the polar groups (CO and NH groups) of acetamide with Li+ and PF6− ions. The strong interaction between LiPF6 and acetamide results in the rupture of the electrovalent bond of LiPF6 and the breakage of hydrogen bonds among the acetamide molecules, leading to the formation of a liquid electrolyte. The LiPF6/acetamide electrolyte with a molar ratio of 1:5.5 exhibits a 5.2 V electrochemical window and suitable ionic conductivity at room temperature. In particular, the coin-type cells with carbon electrodes and LiPF6/acetamide electrolyte possess high thermal stability and electrochemical properties, showing that the as-prepared LiPF6/acetamide electrolyte is a promising candidate for EDLCs.

The (WO3)NCs/Nafion film electrode was prepared by immobilizing the synthesized WO3 NCs on the surface of a glassy carbon electrode (GCE) with the help of Nafion. The ECL emission of the electrode in aqueous solution was affected by the buffer solution with respect to the pH and composition. And the strongest ECL was observed in an NH3–NH4Cl buffer with pH being 8.2. Only a weak ECL peak at 1.14 V which was originated from the annihilation process between oxidized and reduced species of WO3 NCs was found. By adding coreactant triproplamine (TPrA) in buffer solution, an additional ECL peak at 1.13 V which was attributed to the electron-transfer reaction between the oxidized WO3 NCs and reduced intermediate of TPrA was observed. The (WO3)NCs/Nafion film electrode exhibits excellent ECL property and good stability, which would promote the potential application of WO3 NCs as a luminescence material for solid-state ECL detection.Highlights► The preparation, characterization of WO3 nanocrystals. ► The ECL behavior of WO3 nanocrystals. ► One weak ECL peak at 1.14 V was observed in aqueous solution with the absence of the coreactant TPrA. ► Two ECL peaks at 1.13 V and 1.14 V were observed in aqueous solution with the presence of the coreactant TPrA.

5-[o-(4-Bromine amyloxy)phenyl]-10,15,20-triphenylporphrin (o-BrPETPP) was electropolymerized on a glassy carbon electrode (GCE), and the electrocatalytic properties of the prepared film electrode response to dopamine (DA) oxidation were investigated. A stable o-BrPETPP film was formed on the GCE under ultrasonic irradiation through a potentiodynamic process in 0.1 M H2SO4 between −1.1 V and 2.2 V versus a saturated calomel electrode (SCE) at a scan rate of 0.1 V s−1. The film electrode showed high selectivity for DA in the presence of ascorbic acid (AA) and uric acid (UA), and a 6-fold greater sensitivity to DA than that of the bare GCE. In the 0.05 mol L−1 phosphate buffer (pH 6.0), there was a linear relationship between the oxidation current and the concentration of DA solution in the range of 5 × 10−7 mol L−1 to 3 × 10−5 mol L−1. The electrode had a detection limit of 6.0 × 10−8 mol L−1(S/N = 3) when the differential pulse voltammetric (DPV) method was used. In addition, the charge transfer rate constant k = 0.0703 cm s−1, the transfer coefficient α = 0.709, the electron number involved in the rate determining step nα = 0.952, and the diffusion coefficient Do = 3.54  10−5 cm2 s−1 were determined. The o-BrPETPP film electrode provides high stability, sensitivity, and selectivity for DA oxidation.

The oxide films of nickel electrode formed in 30 wt.% KOH solution under potentiodynamic conditions were characterized by means of electrochemical, in situ PhotoElectrochemistry Measurement (PEM) and Confocal Microprobe Raman spectroscopic techniques. The results showed that a composite oxide film was produced on nickel electrode, in which aroused cathodic or anodic photocurrent depending upon polarization potentials. The cathodic photocurrent at −0.8 V was raised from the amorphous film containing nickel hydroxide and nickel monoxide, and mainly attributed to the formation of NiO through the separation of the cavity and electron when laser light irradiates nickel electrode. With the potential increasing to more positive values, Ni3O4 and high-valence nickel oxides with the structure of NiO2 were formed successively. The composite film formed in positive potential aroused anodic photocurrent from 0.33 V. The anodic photocurrent was attributed the formation of oxygen through the cavity reaction with hydroxyl on solution interface. In addition, it is demonstrated that the reduction resultants of high-valence nickel oxides were amorphous, and the oxide film could not be reduced completely. A stable oxide film could be gradually formed on the surface of nickel electrode with the cycling and aging in 30 wt.% KOH solution.

•The spent Zn–Mn batteries collected from manufacturers is the target waste.•A facile reclaiming process is presented.•The zinc is reclaimed to valuable electrolytic zinc by electrodepositing method.•The manganese elements are to produce valuable LiNi0.5Mn1.5O4 battery material.•The reclamation process features environmental friendliness and saving resource.A process for reclaiming the materials in spent alkaline zinc manganese dioxide (Zn–Mn) batteries collected from the manufacturers to prepare valuable electrolytic zinc and LiNi0.5Mn1.5O4 materials is presented. After dismantling battery cans, the iron cans, covers, electric rods, organic separator, label, sealing materials, and electrolyte are separated through the washing, magnetic separation, filtrating, and sieving operations. Then, the powder residues react with H2SO4 (2 mol L−1) solution to dissolve zinc under a liquid/solid ratio of 3:1 at room temperature, and subsequently, the electrolytic Zn with purity of ⩾99.8% is recovered in an electrolytic cell with a cathode efficiency of ⩾85% under the conditions of 37–40 °C and 300 A m−2. The most of MnO2 and a small quantity of electrolytic MnO2 are recovered from the filtration residue and the electrodeposit on the anode of electrolytic cell, respectively. The recovered manganese oxides are used to synthesize LiNi0.5Mn1.5O4 material of lithium-ion battery. The as-synthesized LiNi0.5Mn1.5O4 discharges 118.3 mAh g−1 capacity and 4.7 V voltage plateau, which is comparable to the sample synthesized using commercial electrolytic MnO2. This process can recover the substances in the spent Zn–Mn batteries and innocuously treat the wastewaters, indicating that it is environmentally acceptable and applicable.

In this paper, the electrochemical oxidation and differential pulse voltammetry (DPV) determination of catechol (CC) and hydroquinone (HQ) are studied at a novel carbon nano-fragment (CNF) modified glassy carbon electrode (CNF/GCE). The CNF modifier is prepared using the graphite cycled in lithium-ion batteries as the raw material through a ball mill process. The redox reactions of CC and HQ at the CNF/GCE are a two proton and electron process and controlled by the diffusion step. Compared to the GCE, the as-prepared CNF/GCE shows enhanced electrocatalytic activity and a peak potential difference of about 104 mV towards the oxidation of CC and HQ in a 0.1 mol L−1 acetate buffer solution (ABS, pH = 5.9), which makes it suitable for simultaneous determination of CC and HQ by DPV. Under the optimized conditions, the oxidation peak current of CC is linear over a range from 2.0 × 10−6 mol L−1 to 2.0 × 10−4 mol L−1 in the presence of 5.0 × 10−5 mol L−1 HQ with a detection limit of 1.0 × 10−7 mol L−1 (S/N = 3). Correspondingly, the oxidation peak current of HQ is linear over a range from 6.0 × 10−6 mol L−1 to 2.0 × 10−4 mol L−1 in the presence of 5.0 × 10−5 mol L−1 CC with a detection limit of 2.5 × 10−7 mol L−1 (S/N = 3). In addition, this CNF/GCE exhibits high selectivity, reproducibility and stability, showing its promising application prospect.

A reconstructed graphite-like carbon (r-GC) micro/nano-structure with a higher capacity than and a comparative voltage plateau to commercial graphite anodes of lithium-ion batteries (LIBs) is synthesized from an expandable graphite raw material based on an up-down-up synthetic strategy. The expandable graphite powders are thermally expanded, hydrothermally cut, and ultrasonically crushed in turn to prepare a suspension containing nano-fragments with a graphitic plane nano-structure as a carbon precursor. Then, the r-GC micro/nano-structure can be obtained by stacking the graphite nano-fragments through spray drying the suspension and subsequently conducting a calcining treatment. This r-GC exhibits an initial capacity of 575.3 mA h g−1 at 0.1C and a reversible capacity of 508.4 mA h g−1 after 100 cycles. Especially, its comparative voltage plateau of commercial graphite is incapable for other known anode materials for LIBs. In the potential window of 0.3–0.01 V (vs. Li+/Li), a maximum capacity of approximately 432.1 mA h g−1, 1.16 times the theoretical capacity of graphite (372 mA h g−1), is obtained. The unique element stability, capacity, and voltage plateau indicate that the as-synthesized r-GC is a promising sheet-like anode material for LIBs. In addition, an embedded-defect and graphite-dominant graphite/graphene cooperative lithiation mechanism is proposed to elaborate the capacity and voltage plateau of r-GC.

In this paper, the direct electrochemical oxidation and differential pulse voltammetry (DPV) determination of guanine and adenine are studied by using an electrochemically reduced graphene oxide (er-GO) modified glassy carbon electrode (er-GO/GCE). Compared to the GCE and the GO/GCE, the as-prepared er-GO/GCE shows excellent electrocatalytic activity towards guanine and adenine, with an increase of oxidation current along with a negative shift of oxidation potential. Using the as-prepared er-GO/GCE, the simultaneous determination of guanine and adenine is successfully carried out, and the detection limits (based on S/N of 3) for guanine and adenine are 1.5 × 10−7 mol L−1 and 2.0 × 10−7 mol L−1, respectively. In addition, this er-GO/GCE exhibits a high selectivity, reproducibility and stability, and also can be used for the detection of guanine and adenine in the thermally denatured calf thymus DNA and urine, showing its promising application in the analysis of real samples.

A series of bismuth oxyhalides with controllable composition and band structure have been successfully synthesized by a facile and general one-pot hydrothermal route using Bi2O3 as the starting material; their band structures and visible-light-induced photocatalytic performances are investigated.