•We fabricated the PB/carbon nanopolyhedra/polypyrrole electrode for first time.•Carbon nanopolyhedra are found to promote the synthesis of PB for the first time.•Excellent electrocatalytic activity toward hydrazine detection.A novel low-cost and highly efficient hydrazine sensor based on nitrogen-doped carbon nanopolyhedra (CNP), Prussian blue (PB) and conductive polymer is synthesized. CNP containing cobalt, which were prepared via pyrolysis of the Zeolitic Imidazole Framework-67 (ZIF-67), are found to be catalytically active for the synthesis of PB. Polypyrrole (PPy) is then coated on the PB/CNP composite to provide high conductivity and an environmental stability of the PB/CNP/PPy compound. The as-prepared electrode was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and electrochemical methods. The electrode modified with PB/CNP/PPy exhibits an excellent activity for the electrocatalytic oxidation of hydrazine. It demonstrated a rapid response of less 2 s, a sensitivity of 0.22 A M−1, a long linear range from 7.5 × 10−7 M to 1.7 × 10−3 M and a low detection limit (S/N = 3) of 2.9 × 10−7 M, as well as a remarkable stability and selectivity.Download high-res image (57KB)Download full-size image

The CoFe Prussian blue analogue/carbon nanotube composite material was synthesized and applied to catalyze the reaction of epoxidation of styrene. Carbon nanotubes were used as catalyst carriers. The catalytic activity of this composite material was superior to the CoFe Prussian blue analogue and carbon nanotubes taken independently. The composite material indeed had a larger surface area and a better particle dispersion than the bulk Prussian blue analogue. Kinetic studies were also carried out. The reaction activation energy of the CoFe Prussian blue analogue alone was equal to 75.83 kJ mol−1, while the reaction activation energy of the composite material was equal to 35.67 kJ mol−1. A first order reaction with respect to the concentrations of catalyst, styrene and tert-butyl hydroperoxide was also determined. The composite catalyst could be reused for up to five cycles without any significant loss in conversion and selectivity.

•Prussian Blue (PB) deposition on Ag/GF for electrochemical hydrazine sensing;•Lower detection limit of 4.9 × 10−7 mol L−1, stable over 24 days;•High sensitivity: 26.06 A mol−1 L.In this study, a triple-component hydrazine sensor (PB@Ag/GF) was fabricated with freestanding graphite felt (GF), silver nanoparticles (Ag) and prussian blue (PB). The Ag nanoparticles were electrodeposited on GF ultrasonically (Ag/GF), and acted as a catalyst of the chemical deposition of PB. The electrode was characterized by scanning election microscopy (SEM), infrared spectroscopy (IR), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The electrochemical behavior of PB@Ag/GF was measured by cyclic voltammetry and amperometric measurements. The sensor displayed a prominent electrocatalytic activity toward hydrazine oxidation, with a fast response time of 2 s, a low detection limit of 4.9 × 10−7 mol L−1 and very high detection sensitivity of 26.06 A mol−1 L.

In this article, a new application of the room temperature ionic liquid, tetramethylammonium tetrafluoroborate, is described. This ionic liquid is used as a stabilizing agent and the reaction medium for the synthesis of CoFe Prussian blue analogue nanoparticles using N,N-dimethyl formamide as a complexing agent. The as-synthesized Prussian blue analogues were characterized by various techniques and were used to catalyze the reaction of epoxidation of styrene. The catalytic activity of Prussian blue analogues prepared in ionic liquid was superior to that of Prussian blue analogues prepared in aqueous solution.

The catalytic epoxidation of styrene was carried out using tert-butyl hydroperoxide (TBHP) in the presence of Prussian blue analogues (PBA) as catalysts and the reaction parameters of the epoxidation, such as temperature, solvent and reaction time, have been optimized. Optimum reaction conditions led to 96% conversion of styrene with selectivity in styrene epoxide equal to 64%. Furthermore, a kinetic investigation of the epoxidation of styrene with TBHP has been studied, a first order with respect to the concentrations of styrene, TBHP and catalyst were determined and an apparent activation energy value of 100.4 kJ mol−1 was obtained.

In this study, a novel composite of cobalt hexacyanoferrate nanoparticles (CoNP) and platinum nanoparticles (Pt) on carbon nanotubes (CNTs) is obtained by ultrasonically mixing CoNP synthesized in a microemulsion with CNTs chemically modified with platinum nanoparticles (Pt/CNTs). Cyclic voltammetric and amperometric measurements on a glass carbon electrode showed that the composite (called CoNP–Pt/CNTs) exhibits a well-defined pair of redox peaks and a prominent electrocatalytic activity toward hydrogen peroxide (H2O2) reduction. Besides, the current response of CoNP–Pt/CNTs is 2 orders of magnitude higher than the response of CoNP alone and 1 order of magnitude higher than the response of Pt/CNTs or CoNP/CNTs alone. This higher efficiency can be attributed to a remarkable synergistic effect between CoNP, Pt and CNTs. This sensor shows a linear response to H2O2 concentrations ranging from 0.2 μM to 1.25 mM with a detection limit of 0.1 μM, a maximum sensitivity of 0.744 A·M−1 and a fast response time below 2 s.

In this study, we report a triple-component sensor fabricated by freestanding graphite felt (GF), platinum nanoparticles (Pt) and Prussian blue (PB). Pt is ultrasonically-electrodeposited on GF to increase the conductivity and to render the catalysts to the chemical deposition of PB. Cyclic voltammetric and amperometric measurements show that the double porous PB@Pt/GF sensor exhibits two pairs of well-defined redox peaks and a prominent electrocatalytic activity toward H2O2 reduction. This resulting sensor displays impressive results with regard to a low detection limit of 1.2×10−9 M and very high detection sensitivity of 40.9 A cm−2 M−1, using a potential work of 0.0 V.Highlights► Graphite felt is used in the construction of electrochemical sensors as a working electrode material. ► Graphite felt is specifically selected as the support for Prussian blue-growth. ► The zeolite-like Prussian blue on macroporous graphite felt forms a double porous structure.

Mesoporous pseudoboehmite with novel pore properties was prepared via the direct precipitation method using aluminum nitrate nonahydrate as the inorganic alumina precursor and different surfactants containing bis (2-ethylhexyl) sulfosuccinate sodium salt (AOT), cetyltrimethylammonium bromide (CTAB), and tert-octylphenoxypolyethoxyethanol (Triton X-100) as the structure-directing agents. The as-synthesized mesoporous products were characterized by wide-angle X-ray diffraction (XRD) and transmission electron microscope (TEM) imaging. Pure pseudoboehmite could be obtained when the final pH was between 8 and 10.5, and the presence of different surfactant micelles played an important role in the morphology and growth of pseudoboehmite. In addition, the pore properties could be enhanced significantly by the presence of transition metal ions. Particularly, when nickel nitrate was added to the aluminum nitrate solution at the molar ratio of 0.0040, the specific surface area, the pore volume, and the average pore diameter of pseudoboehmite reached significantly large values of 381 m2/g, 1.18 cm3/g, and 9 nm, respectively.

Herein a series of cobalt–iron Prussian blue analogs (PBAs) containing K+ and Cs+ were synthesized in water-in-oil AOT reverse microemulsions. The size, morphology and composition of the as-prepared cobalt hexacyanoferrate (CoHCF) can be fine-tuned by conveniently varying the water-to-surfactant molar ratio (w) of the microemulsion, as confirmed by various techniques such as infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). These nanostructured PBA were thereafter employed to chemically modify electrodes to thoroughly investigate their electrochemical properties. Oxidized and reduced cobalt hexacyanoferrates were fabricated and characterized in the presence of alkali metal (Li+, Na+, K+, Rb+, Cs+) and NH4+ counteractions by cyclic voltammetry (CV). In addition, it was demonstrated that formal potentials of hexacyanoferrate (III, II) redox reactions were sensitive to the choice of electrolyte cations, and they correlated well with the sizes of hydrated Na+, K+, Rb+, Cs+ and NH4+ except for Li+. Furthermore, the samples are found to vary significantly in permeability, probably due to the difference of composition, structure and morphology of products, and the changes during charging/discharging. Finally, it is noteworthy to highlight that the nanostructures of cobalt hexacyanoferrate synthesized at w = 5–40 had much more electrochemistry stability than that synthesized in aqueous solution in all electrolytes. The potential application of the modified electrode of CoHCF films in electrochromic display was also noticed.Highlights► Cobalt hexacyanoferrate were synthesized in AOT microemulsions and aqueous solution. ► Formal potentials of hexacyanoferrate were sensitive to electrolyte cations. ► Cobalt hexacyanoferrate fabricated at w = 5–40 had enhanced electrochemistry stability. ► The modified electrode of CoHCF films in electrochromic display was also announced.

We synthesized a series of cobalt-iron Prussian blue analogues in the form of nanocubes with which we tuned the amount of Cesium cation in the tetrahedral sites of the structure and varied nature of the alkali cation in the compound adopting a single microemulsion technique. Structure and morphology of the compound had been investigated by combining energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma (ICP), thermo-gravimetry analysis (TGA), infrared spectroscopy (IR), powder X-ray diffraction (XRD) and Transmission electron microscopy experiments (TEM). To directly determine the coercivity, remanence and Curie temperature, superconducting quantum interference device magnetometer (SQUID) was performed. Our investigation suggests that the amount and nature of the alkali cation are critical parameters for understanding the magnetic properties of the nanoparticles.

In this article, a new application of the room temperature ionic liquid, tetramethylammonium tetrafluoroborate, is described. This ionic liquid is used as a stabilizing agent and the reaction medium for the synthesis of CoFe Prussian blue analogue nanoparticles using N,N-dimethyl formamide as a complexing agent. The as-synthesized Prussian blue analogues were characterized by various techniques and were used to catalyze the reaction of epoxidation of styrene. The catalytic activity of Prussian blue analogues prepared in ionic liquid was superior to that of Prussian blue analogues prepared in aqueous solution.