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The poor conductivity of metal-organic frameworks (MOFs) has greatly restricted their widespread application in water splitting. Herein, the Ni-MOF is used to be a precursor to support a stable three-dimensional structure, high surface areas and to prepare various contents of Pd doped Ni alloys (Pd/Ni-1, Pd/Ni-2 and Pd/Ni-3). The hydrogen evolution reaction (HER) activity of samples is compared in alkaline electrolyte (1.0 M KOH). As-prepared catalysts exhibit uniform dispersion, good crystallinity, high purity and a small particle size according to the physical characterization. What is more, based on the electrochemical characterization, Pd/Ni-3 has an exclellent HER performances with a lower overpotential (50 mV in base at 10 mA·cm−2), smaller Tafel slope (102 mV·dec−1) and more positive initial potential (ƞ at 1 mA·cm−2; Δ ƞ = 660 mV) than that of Ni-MOF. The reduction percentage of resistance charge transfer (R ct) relative to Ni-MOF of Pd/Ni-3 is up to 95.6%. This work may offer guidance to make up the low conductivity of MOF for HER in alkaline electrolyte. • Ni-MOF as a precursor supports a stable three-dimensional structure. • The R ct reduction percentage of Pd/Ni-3 is up to 95.6%. • Pd/Ni-3 exhibits satisfactory performance for HER (50 mV at j 10). [ABSTRACT FROM AUTHOR]

• PtAuFe/C composite catalyst and Pt/C catalyst are prepared by sodium borohydride direct reduction method. • The PtAuFe/C composite catalyst has better activity and stability than that of the Pt/C catalyst in H 2 SO 4 solution. • The addition of non-precious metal Fe improves the hydrogen evolution property of PtAuFe/C composite catalyst. In this paper, PtAuFe/C composite catalyst and Pt/C catalyst are prepared by sodium borohydride direct reduction method. The physical properties of the catalysts are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The electrocatalytic hydrogen evolution performance of the prepared catalysts is tested by linear scanning voltammetry (LSV) in H 2 SO 4 solution. The results show that the PtAuFe/C composite catalyst has larger specific surface area, smaller overpotential, higher polarization current density and better stability than that of the Pt/C catalyst. The hydrogen evolution mechanism of PtAuFe/C composite catalyst is determined by Tafel curve, and the results show that PtAuFe/C composite catalyst is of composite desorption mechanism. In addition, the effect of temperature and electrolyte concentration on the performance of PtAuFe/C composite catalyst is also studied. [ABSTRACT FROM AUTHOR]

• A porous anodic alumina (AAO) template is prepared by DC constant voltage anodization and the step-down method. • The pore size of the AAO template is about 60 nm. • Cobalt, nickel and alloy nanowires are prepared by alternating current deposition. • AAO loaded with nanowires had a low hydrogen evolution overpotential and high stability. Water electrolysis is a promising way to produce hydrogen fuel, but many electrocatalytic systems require electrodes made of noble metals such as platinum. There is a demand for high-efficiency, low-cost materials to replace these noble metals. Herein, porous anodic alumina (AAO) templates are prepared by direct current (DC) constant voltage anodization and the step-down method. Cobalt, nickel and Co – Ni alloy nanowires are then prepared by alternating current (AC) electrodeposition. This nanoarray system can be employed in fuel cells to minimize the use of precious metals and reduce the cost of the cathodes. The pores of the AAO template are uniform with a size range from 35 to 75 nm. Using cyclic voltammetry (CV) and linear sweep voltammetry (LSV), the Co–Ni nanowire array prepared on AAO by this method is shown to have a low overpotential for hydrogen evolution and excellent stability. [ABSTRACT FROM AUTHOR]