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Due to the excellent mechanical properties of high entropy alloys (HEAs), they have attracted wide attention of materials researchers, but their functional properties have rarely been reported. In order to study the functional properties of HEAs, the decoloration of azo dye Direct Blue 6 (DB6) using equiatomic AlCrFeMn and AlCrFeMn M (M = Mg, Ti, Ni) HEAs synthesized by mechanical alloying was reported in this work. The decoloration rate of DB6 by ball-milled (BM) AlCrFeMn was about 3 times faster than that of by BM MgZn-based amorphous alloy, which was the best one reported in the metallic glasses so far. In order to further improve the decoloration efficiency, we considered adding the fifth elements (Mg or Ti or Ni) to AlCrFeMn. Both of Mg and Ti could improve the decoloration performance of AlCrFeMn, but Ni played a negative role. The reaction activity of AlCrFeMnMg and AlCrFeMnTi was more than 2 and 1.2 times faster than that of AlCrFeMn. The effects of initial pH, temperatures and dye concentration on the decoloration efficiency of AlCrFeMnMg during reactions were systematically investigated. The reaction activity of AlCrFeMnMg in alkaline and acidic azo dye solution was about 37.5 and 16.6 times faster than that of neutral solution, respectively. This work had implications in reaching an attractive, low cost and efficient method for functional applications of HEAs. [ABSTRACT FROM AUTHOR]

In this work, we report the growth of uniformly dispersed bimetallic cobalt–palladium nanoparticles (NPs) on reduced graphene oxide (RGO) nanosheets to prepare CoPd–RGO composites via a two-step procedure, where firstly formed Co NPs are used as seeds for the subsequent growth of Pd. The generation of Co NPs on RGO is performed by an in-situ reduction reaction with the reducer ethylene glycol under oil bath at 180 °C. According to composition, size and microstructure analyses, NPs in the resulting CoPd–RGO have an average particle size of 5 nm, and Pd is added to one side of Co NPs, thus forming Co–Pd bimetallic interfaces. The involved formation mechanism is suggested. The composite is used as an electro-catalyst for the formic acid oxidation in alkaline electrolyte, and the catalytic performance is investigated by cyclic voltammetry and chronopotentiometry etc. The results show that the composite has the highest electro-catalytic activity, the best electrochemical stability and the highest resistance to CO poisoning than those of the monometallic composite and commercial Pd black at the same loading. This is due not only to the small size of NPs with Co–Pd bimetallic interfaces providing more active atoms accessible for reactants, but also to the electric synergistic effect between metals and graphene. [ABSTRACT FROM AUTHOR]

In this paper, we report a simple one-step thermal reducing method for synthesis of bimetallic Au@Pd nanoparticles with core-shell structures on the graphene surface. This new type of Au@Pd–G composites is characterized by transmission electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. It is found that Au@Pd nanoparticles with an average diameter of 11 nm are well dispersed on the graphene surface, and the Au core quantity as well as the Pd shell thickness can be quantitatively controlled by loading different amounts of metallic precursors, and the involved core-shell structure formation mechanism is also discussed. The ternary Pt/Au@Pd–G composites can also be synthetized by the subsequent Pt doping. The catalytic performance of Au@Pd–G composites toward methanol electro-oxidation in acidic media is investigated. The results show that Au@Pd–G composites exhibit higher catalytic activity, better stability and stronger tolerance to CO poisoning than Pd–G and Au–G counterparts. [ABSTRACT FROM AUTHOR]

A method for preparing a graphene oxide/polyaniline (GO/PANI) composite electrode was developed to investigate the effect of GO doped in PANI. PANI was first prepared by the polymerisation of aniline and then dedoped by NH4OH to form emeraldine base (EB). The dedoped PANI and as-prepared GO were dissolved in N-methyl-2-pyrrolidone (NMP) to generate a homogeneous dispersion. The GO/PANI composites were redoped in HCl before use as electrode materials. These composites were characterised by Raman spectroscopy, X-ray diffraction, UV–vis adsorption spectroscopy, scanning electron microscopy, atomic force microscopy and electrochemical measurements. The GO/PANI composite electrode (containing 2.5% GO) has an initial gravimetric capacitance of 896 F g−1 at a scan rate of 5 mV s−1 and a retention life of 51% after 500 cycles, which is an improvement over that of pure PANI (23%). The results show that the synergy of GO and PANI attributes to the good electrochemical performance of the GO/PANI composite electrode. [Copyright &y& Elsevier]

Cu–C co-coated LiFePO4 (LiFePO4/(C + Cu)) cathode material was successfully prepared through solid state reduction reaction. The optimized additive amount of CuO was determined by electrochemical test of series content-dependent samples. Electrochemical performances of LiFePO4/(C + Cu) cathode material were investigated. Crystalline structure, morphology and electrochemical performance of the samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), charge–discharge tests and AC impedance techniques. Results showed that crystal structure of the bulk material was not destroyed after Cu particles distributed on the surface of LiFePO4/C. With 5 wt% CuO additive, the LiFePO4/(C + Cu) cathode material showed improved electrochemical performance especially at high rates and low temperature. At 25 °C and 0.1 C current rate, specific capacity of the Cu-coated sample reaches 161.3 mA h/g. The result was 47 mA h/g higher than that of the un-coated one. At −20 °C, the discharge capacity of Cu-coated materials was 113.4 mA h/g at 0.1 C rate and 83.8 mA h/g at 5 C rate, which reached about 70% of that at room temperature, respectively. [ABSTRACT FROM AUTHOR]