Nickel Electrocatalyst Research Articles

Structural and morphological characterization of gold–nickel electrocatalyst synthesized by taking advantage of the AuNi phase separation mechanism

The Au–Ni bimetal nanoparticles were prepared by coreduction in aqueous solution and post-heat-treatment process. In this synthesis approach, NaBH4 was used as reductive reagent and sodium dodecyl sulfate was added as surfactant to control the size and the morphology of the nanoparticles. Post-heat-treatment was performed to further remove the oxide species on the surface of the nanoparticles. Structural and compositional evolution analysis of the nanostructured bimetals are performed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectrometry (XPS) measurements. The Au–Ni electrocatalysts for electro-oxidation of formic acid in acidic media were investigated.

Hydrogen production using cobalt-based molecular catalysts containing a proton relay in the second coordination sphere

The cobalt analogue of a highly active nickel electrocatalyst for hydrogen production has been synthesized and characterized as [Co(PPh2NPh2)2(CH3CN)](BF4)2. In the presence of triflic acid in acetonitrile solution, the complex loses one cyclic diphosphine ligand to form [Co(PPh2NPh2)(CH3CN)3](BF4)2, which has been synthesized independently and stucturally characterized. The latter complex serves as an electrocatalyst for hydrogen formation with a turnover frequency of 90 s−1 and an overpotential of 285 mV using bromoanilinium tetrafluoroborate as the acid. A similar cobalt complex with a related diphosphine ligand that does not contain a pendant base is not catalytically active, confirming an important role for the pendant amine in the catalytic reaction.

A novel titanium-supported nickel electrocatalyst for cyclohexanol oxidation in alkaline solutions

Abstract A novel titanium-supported nickel electrode (Ni/Ti) is fabricated by a simple hydrothermal process using hydrazine hydrate as a reduction agent. Its electrocatalytic activity towards cyclohexanol oxidation has been investigated by cyclic voltammetry (CV), chronoamperometry (CA), quasi-steady state polarization and electrochemical impedance spectroscopy (EIS). Effects of various parameters such as potential scan rate and cyclohexanol concentration on the electro-oxidation of cyclohexanol are investigated. Results show that the Ni/Ti electrode behaves as an efficient catalyst for the electro-oxidation of cyclohexanol in basic media and its electrocatalytic activity towards cyclohexanol oxidation is higher than a nickel oxyhydroxide modified nickel electrode (NOMN). It is confirmed that during the anodic potential sweep the electro-oxidation of cyclohexanol follows the formation of NiOOH on the electrode surface and is then catalysed by NiOOH. The rate-determining step for cyclohexanol oxidation is the reaction between the high oxidation state nickel (Ni 3+ ) and the adsorbed cyclohexanol on the surface of the Ni/Ti.

Comparisons of Ebonex® and graphite supports for platinum and nickel electrocatalysts

The electrogenerative oxidation of simple aliphatic and aromatic alcohols and formaldehyde has been investigated for platinum and nickel on supported Ebonex® catalysts with sulfuric acid and sodium hydroxide electrolytes. Comparisons were made with similarly prepared metal catalysts on graphite to permit some inferences concerning the effect of the support. The Ebonex® support caused a decrease in the activity of the supported platinum catalyst, but enhanced the activity of the supported nickel catalyst, which was particularly effective for formaldehyde oxidation with base even exceeding that of the platinum/graphite catalyst. The effect of a tin–palladium pretreatment, used for the deposition of the metals, was also investigated on the Ebonex® catalysts. The pretreatment improved performance, but not to the extent observed for graphite supports. Possible origin of the support interactions is discussed.

Electrochemical Reduction of CO2 in Micropores

Abstract CO2 electroreduction was examined on high area nickel electrocatalysts supported on activated carbon fibers, which contain slit-shaped pores with widths on the order of nanometers. The current efficiency for CO2 reduction to CO reached values of 70%. In contrast, much smaller amounts of CO were generated for the same type of high area nickel catalyst supported on non-activated carbon fibers. The enhancement of the CO2 reduction selectivity with the microporous support is thought to include a nanospace effect, which gives rise to high pressure-like effects at ambient pressure.

Development of highly durable low hydrogen overvoltage cathode in chlor-alkali cells

A novel cathode with a metal hydride and a Raney nickel electrocatalyst has been developed for highly durable low hydrogen overvoltage cathodes in chlor-alkali electrolysis cells. The cathode is made by composite-coating a Raney nickel alloy and a metal hydride on a cathode substrate. The cathode exhibits a low hydrogen overvoltage ( ca 80 mV at 90°C, at 30 A dm 2in a 35 wt% NaOH), and has excellent stability under cell short-circuiting shutdowns as well as under normal operating conditions. The mechanism of the excellent stability under shutdown conditions has been discussed.

Advanced low hydrogen overvoltage cathode for chlor-alkali electrolysis cells

An advanced low hydrogen overvoltage cathode has been developed for use in chlor-alkali electrolysis cells. The cathode is made by composite-coating a novel ternary Raney nickel electrocatalyst on a variety of substrates. The results of many performance tests in laboratory cells as well as commercial cells are reported. The cathode exhibits a low hydrogen overvoltage (50–70 mV at 90°C, at 30 A dm −2 in a 35 wt% NaOH), excellent stability under cell short-circuiting conditions and a considerably long cathode life, up to the present four years in commercial plants. The excellent stability of the cathode against cell shutdown conditions has been discussed.