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In this paper, iron and nitrogen co-doped carbon material with nanotube structure (Fe/N-CCM-T) was synthesized by pyrolyzing a mixture of Fe salt, chitosan and melamine and displayed high electrocatalytic performance for oxygen reduction reaction (ORR). The structure of the Fe/N-CCM-T was characterized and their ORR performance in alkaline media was investigated by linear sweep voltammetry, cyclic voltammetry and chronoamperometry. Fe/N-CCM-T displayed better ORR performance than other carbon materials like Fe/N-CC-800. The Fe/N-CCM-800 with a large surface area (302.5 m2/g) especially exhibited the best ORR electrocatalytic performance among the prepared carbon materials, which was also proved by its similar Tafel slope (76 mV decade−1) to Pt/C catalyst (74 mV decade−1). Fe/N-CCM-800 showed similar ORR activity as commercial Pt/C catalyst, but superior tolerance to methanol and stability. Such high ORR performance of the Fe/N-CCM-T can be attributed to its nanotube structure, high specific surface area (SSA), high graphitic-N and pyridinic-N contents.

Polystyrene with π-conjugated end groups (BPS) synthesized by reversible addition–fragmentation transfer polymerization was used to modify the surface of reduced graphene oxide (rGO) sheets through π–π stacking (BPS–rGO) in order to increase their hydrophobicity and dispersibility. The modification of rGO makes it possible for BPS–rGO to stabilize Pickering w/o (water-in-oil) emulsions of small droplets, in which toluene is taken as the continuous phase and distilled water as the dispersed phase. The effects of the BPS–rGO concentration and the water/oil ratio on the Pickering emulsions were investigated. The results indicate that increasing hydrophobicity of BPS–rGO was favorable to forming stable w/o emulsions and the emulsion stability was increased with the increase in the BPS–rGO concentration or with the decrease in water/oil ratio. Using BPS–rGO to stabilize Pickering w/o emulsions is an effective and versatile approach to fabricate active materials that can be employed as catalysts for chemical reactions.

In this work, hierarchical zinc cobalt sulfide flowers on nickel foam (f-Zn0.76Co0.24S/Ni foam) are fabricated by a facile two-step hydrothermal method. The obtained f-Zn0.76Co0.24S/Ni foam are directly used as the binder-free electrodes for high-performance supercapacitors. The as-prepared f-Zn0.76Co0.24S/Ni foam exhibite a high specific capacitance of 1906 F g−1 at a current density of 1 A g−1 and good rate performance. The excellent electrochemical performance can be attributed to the unique interconnected flower structure, which provides a path for the rapid diffusion of electrolyte ions. Moreover, the f-Zn0.76Co0.24S/Ni foam//Fe2O3@rGO asymmetric supercapacitor is assembled. It can achieve a high energy density of 75.7 Wh kg−1 at a power density of 700.5 W kg−1 and display superior cycling stability with 86.7% retention after 8000 cycles.

Carboxymethyl cellulose (CMC) gel membranes were prepared by a chemical crosslinking method and an in situ method was used to load CdS nanoparticles with an average size of about 3 nm into the CMC gel. The negative ion groups in the CMC serve as strong binding sites for the metal ions and help prevent aggregation of the CdS nanoparticles during their growth process. This results in a CMC gel matrix loaded with stable and well-dispersed CdS nanoparticles (CdS-CMC). Pt co-catalyst particles were also loaded into the gel membrane to give CdS/Pt-CMC and both materials were used as photocatalysts for the production of hydrogen. The CdS/Pt-CMC catalyst with 5 wt % Pt exhibited a H2 evolution rate of 1365 μmol h−1 g−1, which is 81 times that of pure CdS. This improvement can be attributed to the separation of the CdS photo-generated electron-hole pairs. The photo-electrons are transferred to Pt and the formed aqueous H+ ions are then rapidly converted to H2. The incorporation of the photocatalyst into a gel matrix makes the photocatalyst easily recoverable which can help avoid environmental pollution caused by free CdS nanoparticles.

Uniform and highly dispersed magnesium hydroxide nanoparticles were synthesized in cetyltrimethyl ammonium bromide/cyclohexane/isopropanol/water microemulsion. The effect of different exper...

Waste water treatment with adsorbents has become one of the most effective methods. In this work, we have reported the preparation of the flower-like Cu2MoS4/g-C3N4 composites. The Cu2MoS4 nanosheets were arranged in a flower-like structure by a simple one-step hydrothermal synthesis method and attached to g-C3N4 nanosheets. The as-prepared flower-like Cu2MoS4/g-C3N4 composites was found to have potential for the adsorption of RhB in aqueous solution. The microstructure of the product was analyzed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscope (XPS), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET). The effects of the ratio of the composite material, the initial concentration of the dye and the contact time were explored. The Langmuir maximum adsorption capacity of the flower-like Cu2MoS4/g-C3N4 composites for RhB was reached 420.2 mg/g. Moreover, the adsorption process is consistent with the pseudo second-order kinetic model, the Langmuir isotherms model and the Freundlich isotherms model.

Cobalt nanoparticles supported elastic foam (Co-F) was prepared by coating commercial polyurethane foam with cobalt nanoparticle loaded hybrids (Co/rGO). The Co-F was applied to catalyze hydrolysis reaction of sodium borohydride to produce hydrogen gas. Co-F has large surface area and interconnected pores, so it showed outstanding activity in catalyzing the hydrolysis reaction and achieved a hydrogen production rate of 33.2 mL·min−1. The conditions for Co/rGO and Co-F preparation as well as reaction conditions like the reaction temperature, the concentration of NaBH4 and pH value all affected the catalytic hydrolysis of NaBH4. The Co-F could be easily recovered by taking out, pressing and rinsing in distilled water, and it exhibited almost unfaded catalytic activity in the reusage. The unique properties will make Co-F potential applications in catalytically chemical reactions.

Biomass-derived nitrogen-self-doped carbon was prepared by a simple and green approach based on the direct pyrolysis of pork heart using KOH as an activation reagent at controlled temperatures (700–900 °C). The obtained samples displayed a specific surface area up to 1718.84 m2 g−1, high content of nitrogen (3.03%) and interconnected porous structure, which is able to expose abundant active sites and promote mass transfer. Electrochemical measurements showed that our catalyst possessed a high electrocatalytic activity for oxygen reduction reaction in alkaline solution that is equivalent to that of commercial Pt/C. The sample carbonized at 700 °C (PC-APHs-700) with the onset potential of 0.92 V and half-wave potential of 0.80 V possessed the highest concentrations of graphite and pyridine nitrogen and exhibited the best performance among the PC-APHs-T samples. In addition, PC-APHs-700 had a higher long-term stability and stronger methanol tolerance than commercial Pt/C. This work demonstrates that it is a promising approach to develop and utilize carbon materials with added value as effective metal-free cathode catalysts for alkaline fuel cells based on economic and environmental friendly renewable biomass.

A facile and efficient approach was employed to synthesize CuFe2O4/rGO (reduced graphene oxide) nanocomposites. The morphology, crystal structure and properties of the prepared CuFe2O4/rGO nanocomposites were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, powder X-ray diffraction and thermo-gravimetric analysis. The CuFe2O4/rGO nanocomposites were applied as adsorbents to study their adsorption performance for Congo red. The adsorption capacity and recyclability, adsorption dynamics and adsorption models were investigated. The results show that the CuFe2O4/rGO nanocomposites are efficient and recyclable adsorbents.

An approach of combining simple precipitation method and thermal annealing was developed to synthesize Co chromite spinel nanoparticles that could be applied as the cathode material for supercapacitors. The nanoparticle modified electrode displayed a high specific capacitance of 418 F/g at the scan rate of 5 mv/s in a three-electrode system.

CuFe2O4/reduced graphene oxide (RGO) nanostructures were fabricated by a facile chemical method, and the shape and size of the CuFe2O4 nanoparticles were tuned through changing the concentration of the reactants and the reaction temperature. The CuFe2O4/RGO nanostructures were firstly analyzed by transmission electron microscopy, Fourier Transform infrared spectroscopy and powder X-ray diffraction, and then they were exploited as magnetically recyclable catalyst for the hydrolytic dehydrogenation of NaBH4 for hydrogen evolution. They exhibited superior catalytic activity and recyclability. The calculated activation energy was 33.95 kJ mol−1, which is even lower than some metallic nanoparticle catalysts. So the CuFe2O4/RGO nanostructures will find potential applications as magnetically recyclable catalysts in hydrogen storage system for fuel cell applications.

Here, novel iron and cobalt co-doped carbon materials (Fe/Co–N–C) with high electrocatalytic activity for oxygen reduction reaction (ORR) were successfully fabricated from pyrolysing the mixture of lactone tofu, ferrous(II) chloride and cobalt(II) chloride. The structure and properties of the materials were evaluated by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), Raman spectroscopy and Brunauer–Emmett–Teller (BET) method. The electrocatalytic activity and stability of the Fe/Co-N-C materials were evaluated by cyclic voltammetry, linear sweep voltammetry and chronoamperometry, accelerated durability test (ADT) in alkaline media. Among the Fe/Co-N-C materials, Fe/Co-N-C700(3) (the molar ratio of Fe/Co is 3 and the annealing temperature is 700 °C) has the best performance of electrocatalytic activity. Compared with commercial Pt/C catalyst, the synthetic Fe/Co-N-C700(3) exhibited similar electrocatalytic activity, superior methanol tolerance and durability. The high ORR activity of the Fe/Co-N-C700(3) catalyst is due to the high contents of the pyridinic-N, graphitic-N, Fe/Co-N as well as high specific surface area. This work provides a simple and efficient method to develop non-precious metal electrochemical catalysts for ORR.