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The present study investigated the surface morphology, phase composition, mechanical properties, and corrosion resistance of Ni-W alloy coatings prepared under current densities of 1–5 A/dm², after undergoing heat treatment at 400 °C, 600 °C, and 900 °C. The grain size of the as-plated Ni-W alloy coating was below 10 nm. After heat treatment at different temperatures, the grain size increased, reaching a maximum value of around 30 nm at 900 °C. Heat treatment crystallized and altered the structure of the coating. Different heat treatment temperatures yielded different precipitates, including Ni4W, Ni6W6C, and WC. The highest coating hardness (820–940 Hv) was achieved at 400 °C, while the best corrosion resistance was achieved at 600 °C. The precipitation hardening phase can be obtained by proper heat treatment temperature, yielding the desired properties of the composite coating. [ABSTRACT FROM AUTHOR]

Ni‐P alloys have been successfully electrodeposited in the choline chloride and ethylene glycol with a molar proportion of 1:2(CE) electrolyte and their activities toward hydrogen evolution reaction (HER) have been also evaluated. The electrodeposition of Ni‐P alloy follows a co‐deposition process, and the bulk growth of which depends on an instantaneous nucleation under diffusion control. The morphologies of Ni‐P alloys are significantly influenced by the P content, and low P content can lead to a smooth surface. As expected, Ni‐9.0 wt.% P alloy shows an impressive HER catalytic performance with a Tafel slope (b) of 72.9 mV dec−1 and an overpotential of 105 mV at 50 mA, in agreement with its large ECSA (Cdl = 3.25 mF cm−2) and small interface charge‐transfer resistance. More interestingly, Ni‐9.0 wt.% P alloy exhibits a sustainable catalytic activity toward HER after 1000 cycling test with a tiny potential decline of ~10 mV at 100 mA cm−2. Such a striking HER activity of Ni‐9.0 wt.% P alloy can be attributed to the synergistic effect among the induced active sites from lattice contraction, negatively charged P incorporation, and a mixed nanometre crystal and amorphous structure. Thus, Ni‐P alloy electrodeposited in a CE‐based electrolyte can be used as a promising electrode material with high HER activity in alkaline solutions for hydrogen production. [ABSTRACT FROM AUTHOR]

A Ni-W alloy containing about 13at.% of tungsten was deposited on carbon cloth (CC) by electrodeposition initially, and then carbon nanotubes (CNTs) were grown thereon by chemical vapor deposition (CVD), fabricating a selfsupported CNTs/Ni-W/CC composite electrode. The results of electrochemical test showed that the composite electrode exhibited good catalytic performance for hydrogen evolution reaction (HER) in 1 mol/L NaOH aqueous solution. The CNTs/Ni-W/CC composite electrode fabricated at 900 °C (the temperature of heat preservation in CVD) showed the best electrocatalytic activity among all the prepared samples. Its overpotential was 118.2 mV at a cathodic current density of 10 mA/cm2 and its Tafel slop was 97.4 mV/dec. The cathodic current density of this composite electrode could exceed that of commercial Pt/C material at a relatively high overpotential. This composite electrode also showed good long-term stability for HER. [ABSTRACT FROM AUTHOR]

Co-W/CeO 2 composite coatings were electrodeposited under galvanostatic conditions from a citrate plating bath containing suspended micro-CeO 2 particles. The composition, structure and morphology of the composite coatings were evaluated and compared when different concentrations of micro-CeO 2 particles are added. The as-prepared Co-W coating without CeO 2 has an amorphous structure. However, embedding CeO 2 into the Co-W matrix considerably improved the crystallinity of the Co-W alloy. The surface morphology study revealed that Co-W/CeO 2 composite coatings were more compact with fewer microcracks and defects than the Co-W coating. The electrocatalytic performance of these composite coatings for hydrogen evolution reaction (HER) was also investigated by liner sweep voltammetry and electrochemical impedance spectroscopy techniques in alkaline medium. Co-W/CeO 2 composite coatings gained remarkable improvement in HER activity which may be attributed to a synergistic eletrocatalytic effect between CeO 2 particles and Co-W matrix. The apparent exchange current density value (j 0 ) of the Co-W/CeO 2 composite coating was 15.6 times higher than that of the Co-W coating when the concentration of micro-CeO 2 particles in the plating bath is 7 gL -1 (denoted as M3), and the j 0 /R f ratio (intrinsic catalytic activity) was 3.72 × 10 −5 Acm −2 . Furthermore, M3 coating also showed good stability and its apparent activation energy (E a ) of HER was calculated to be 24.59 kJmol -1 , which was significantly lower than that of the Co-W coating. [ABSTRACT FROM AUTHOR]

Cost-effective electrodes with high activity for hydrogen evolution reaction (HER) and durability are required to develop clean and renewable hydrogen energy. In this work, a porous Cu supported Ni-P/CeO 2 composite coating was fabricated by a facile electrodeposition technique. Owing to the contribution from the 3D porous Cu support and the incorporating agglomeration-free and uniformly distributed CeO 2 particles into the Ni-P matrix, the optimal composite coating (porous Cu supported Ni-P/CeO 2 (20 g L-1)) exhibits outstanding electrocatalytic performance with small overpotentials (η) of 118 and 320 mV at a cathodic current density of 10 and 100 mA cm2. Moreover, the composite electrode also presents excellent electrochemical stability in the alkaline solution. This work provides a feasible option to fabricate composite electrodes that may have desirable electrochemical properties for HER. [ABSTRACT FROM AUTHOR]