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The growth of NiCo-LDH/CoNi2S4/rGO composite on Ni foam was achieved with a simple one-step hydrothermal method. The obtained binder-free electrode (NiCo-LDH/CoNi2S4/rGO/Ni foam) was characterized with X-ray diffraction (XRD), field emission microscopy (FE-SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and galvanostastic charge/discharge (GCD). NiCo-LDH/CoNi2S4/rGO/Ni foam demonstrates a unique morphology with nanoparticles and nanowires mingled together, which endows the electrode large surface area as verified by the Brunauer–Emmett–Teller gas sorptometry measurement (BET). NiCo-LDH/CoNi2S4/rGO/Ni foam possesses excellent charge storage capabilities such as high areal capacitance, long cycling life and good rate performance. The asymmetric supercapacitor (ASC) with NiCo-LDH/CoNi2S4/rGO/Ni foam and activated carbon (AC) as positive and negative electrodes was assembled, characterized and successfully applied in practical applications, further confirming the great prospect of NiCo-LDH/CoNi2S4/rGO/Ni foam in energy storage. [ABSTRACT FROM AUTHOR]

A 3D nanoporous Fe, N-doped carbon architecture (CHbG) was prepared by simply carbonizing the hemoglobin glutamer (HbG), the polymerized hemoglobin (Hb) with glutaraldehyde as the cross-linking agent. As cathodic catalyst for oxygen reduction reaction (ORR), CHbG shows onset potentials of 0.87 V vs. reversible hydrogen electrode (RHE) in 0.1 M KOH which is as good as commercial Pt/C catalyst. The ORR catalyzed by CHbG follows 4-electron mechanism and shows good catalytic stability and high methanol tolerance in basic media. [ABSTRACT FROM AUTHOR]

Due to the rapid development of fuel cells, the fabrication of electrocatalysts for oxygen reduction (ORR) with high performance and low-cost is of great significance. Herein, cobalt cations-intercalated montmorillonite (Co-MMT) was prepared by a simple cation-exchange reaction between Na-MMT and cobalt cations. A detailed ORR investigation indicates that the as-prepared nanocomposite of Co-MMT and multiwalled carbon nanotubes (Co-MMT/MWCNT) exhibits better ORR catalytic activity in aqueous alkaline medium with a 4e-route mechanism than Na-MMT, Co-MMT and MWCNT, suggesting the synergistic effect between Co-MMT and MWCNT. Moreover, further research shows that Co-MMT/MWCNT hybrid demonstrated more positive onset potential for ORR, higher oxygen reduction peak current than commercial 5% Pt/C ORR electrocatalyst. [ABSTRACT FROM AUTHOR]

Assembly of NiCo double hydroxide@NiC2O4 porous microspheres on Ni foam was fabricated by the direct anodisation of nickel foam (NF) and the subsequent electrodeposition of NiCo double hydroxide (NiCo-DH). The obtained Ni foam-supported NiCo-DH@NiC2O4 (NiCo-DH@NiC2O4/NF) was used as the binder-free electrode for electrochemical capacitor (EC). The combination of NiC2O4 and NiCo-DH increases the amount of active sites for redox reactions while the hierarchical porous morphology significantly enhances the diffusion of electrolyte. With Ni foam as 3D conductive substrate and current collector, the electronic conductivity of the electrode material was significantly improved and the diffusion of the electrolyte on the electrode surface was effectively enhanced. NiCo-DH@NiC2O4/NF demonstrates a high areal capacity, a good cycling stability and a good rate capability. In addition, a hybrid supercapacitor (HSC) assembled with NiCo-DH@NiC2O4/NF as the positive electrode and activated carbon (AC) as the negative electrode exhibited good performance with high energy density and power density. [ABSTRACT FROM AUTHOR]

In this work, graphene oxide (GO) nanosheets were decorated with gold nanoparticles (AuNPs) and multiwalled carbon nanotubes (MWCNTs) with cetyltrimethyl ammonium bromide (CTAB) as the molecular linker. The anchoring of AuNPs and MWCNTs on GO occurred simultaneously with the formation of the membrane of CTAB/GO complex on glassy carbon electrode (GCE). The obtained binder-free electrode was denoted as AuNP/MWCNT/CTAB/GO/GCE. CTAB played a crucial role in the construction of the modified electrode. First, the film formed by CTAB and GO was highly stable in aqueous solution and adhesive to the GCE surface. Second, CTAB acted as the molecular linker to immobilize AuNPs and MWCNTs on the graphene nanosheets. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) and amperometry were used to investigate the electrochemical behaviors of AuNP/MWCNT/CTAB/GO/GCE. It was found out that the modified electrode presented excellent catalytic capabilities towards the oxidation of hydrazine and the reduction of H2O2. The oxidation current of hydrazine and the reduction current of H2O2 are linear with their concentrations in the range of 1.0-1000 μM and 10-5000 μM, respectively. The detection limits for hydrazine and H2O2 are 0.38 μM and 1.78 μM, respectively. [ABSTRACT FROM AUTHOR]

It has been discovered that the complex formed by cetyltrimethyl ammonium bromide (CTAB) and graphene oxide (GO) is highly stable in aqueous solution and adhesive to the glassy carbon electrode (GCE) surface in our previous research. In this work, the film of CTAB/GO complex was directly formed on GCE and gold nanoparticles were facilely incorporated into the matrix of CTAB/GO complex at the same time. Scanning electron microscopic (SEM) investigation shows that gold nanoparticles were distributed uniformly on the sheets of graphene. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometry were used to investigate the electrochemical behaviors of AuNP/CTAB/GO. The obtained AuNP/CTAB/GO presents excellent catalytic capabilities towards the oxidation of hydroxylamine (HA) and the reduction of H2O2. The oxidation current of HA and the reduction current of H2O2 are linear with their concentrations in the range of 10∼1000 μM and 1.0∼5000 μM, respectively. The detection limits for HA and H2O2 are 3.5 μM and 0.67 μM, respectively. The mechanism of the oxidation of HA on AuNP/CTAB/GO modified GCE was also studied. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWNTs) were employed as the rigid template for the assembly of gold/copper alloy nanoparticles (GCNPs). The MWNT/copper composite film was codeposited on glassy carbon electrode at a constant current and subsequently immersed in aqueous chloroauric acid. The GCNPs, prepared by a simple galvanic reaction, are strongly bound to the MWNTs to form a uniform and compact film on glassy carbon electrode (GCE). Cyclic voltammetry and scanning electron microscopy were used to characterize GCNP/MWNTs. The oxidation process of glucose at the GCNP/MWNT shows two well-defined peaks at −0.30 V and 0.023 V in alkaline aqueous solution. The experimental results indicate that the modification of GCNP/MWNT on the surface of GCE significantly improved the electrocatalytic activity towards the oxidation of glucose. [ABSTRACT FROM AUTHOR]

Polyvinylpyrrolidone (PVP)-grafted multi-walled carbon nanotubes (PVP-MWCNTs) were electrodeposited on a copper substrate from N, N-dimethylformamide using a direct-current electric field. The PVP-MWCNTs were positively charged by covalently grafting PVP chains to MWCNTs in an acidic solution in an ultrasonic bath. During the electrodeposition process, positively charged PVP-MWCNTs moved towards a copper cathode at -4.5V. The effects of electric field strength, MWCNT concentration in the suspension and the solvents used for MWCNT dispersion on the deposition nature of MWCNTs were examined. [ABSTRACT FROM AUTHOR]