Electroless Ni–B supported on carbon for direct alcohol fuel cell applications

Hamid

Surface & Interface Analysis

2014

Electroless Ni-P and Ni-P-TiCN composite coatings have been deposited successfully on Al substrates. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques were applied to study the surface morphology and the chemical composition of the deposited films. Moreover, X-ray diffraction (XRD) proved that Ni-P and Ni-P-TiCN deposits have amorphous structures. The properties of Ni-P-TiCN/Al composite films such as hardness, corrosion resistance and electrocatalytic activity were examined and compared with that of Ni-P/Al film. The results of hardness measurements reveal that the presence of TiCN particles with Ni-P matrix improves its hardness. Additionally, the performance against corrosion was examined using Tafel lines and electrochemical impedance spectroscopy techniques in both of 0.6 M NaCl and a mixture of 0.5 M H 2 SO 4 with 2 ppm HF solutions. The results indicate that the incorporation of high dispersed TiCN particles into Ni-P matrix led to a positive shift of the corrosion potential and an increase in the corrosion resistance for all aluminum substrates after their coating with Ni-P-TiCN. In addition, Ni-P-TiCN/Al electrodes showed a higher electrochemical catalytic activity and stability toward methanol oxidation in 0.5 M NaOH solution compared with that of Ni-P/Al.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and performance of electroless Ni–P–TiCN composite coatings on Al substrate

Hamid

Surface & Interface Analysis

2014

“…5 Compared with the noble metal catalysts, some nickelbased alloys, such as Ni, Ni-B and Ni-Cu-P had been investigated considering their low cost and high catalytic activities. [6][7][8][9][10] Among them dispersed Ni-B electrocatalyst over the other metals by electroless deposition technique had received widespread acceptance. The activity of the Ni-B electrocatalyst is related to its morphology and distribution on the electrode surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…To improve the electroless deposition technique, various kinds of preparation strategies had been tried during the past years. For instance, using dimethyl amine borane (DMAB) instead of KBH 4 as a soft reducing agent to make the reaction slowdown; 11 the presence of Pb 2+ ion as stabilizer can render an electroless deposition bath stable, retard precipitation and accelerate the rate of plating; 12 the moderate stabilization of nickel cation through a source of complexing agent, such as sodium citrate, sodium acetate, ethylenediamine and hydrazine can prevent an abrupt formation of the Ni-B amorphous alloy. 13 14 Usually the effect of complexing agent only considered as improving the stability of the reaction process.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Ni–B Electrocatalyst Prepared from Nickel Ethylenediamine Complex for Direct Ethanol Electrocatalytic Oxidation

Hou¹,

Guo²,

Li³

et al. 2014

j nanosci nanotechnol

Ni-B/Cu electrode prepared by the electroless deposition technique of chemical reduction of nickel ethylenediamine complex with BH4- was characterized by SEM, XRD and XPS techniques, respectively, and evaluated using ethanol electrocatalytic oxidation by the method of cyclic voltammetry. The as-prepared Ni-B/Cu electrode exhibited much higher electrocatalytic activity than the Ni-B/Cu electrode obtained via direct reduction of nickel metallic ions. The effects of the nickel ethylenediamine complex can be attributed to both the structural effect and electronic effect. The nickel ethylenediamine complex can not only make an electroless deposition stable and highly dispersed, but also facilitate the formation of more nanoscale microcrystalline Ni on the electrode surface, which increased the electrochemical oxidation activity. Moreover, ethylenediamine influenced the electronic states of Ni and B on the electrode surface, more electrons transfer from the B to Ni that the Ni active sites became more highly unsaturated, which could promote the form of adsorbed active ethanol.

The electrocatalytic behavior of electrodeposited Ni–Mo–P alloy films towards ethanol electrooxidation

Surface & Interface Analysis

Hamid

2013

Ternary Ni-Mo-P thin films have been electrodeposited from citrate-based electrolyte onto graphite substrates for application as anode catalysts for ethanol electrooxidation. The operating deposition parameters were optimized to produce Ni-Mo-P alloy films of outstanding catalytic activity. The phase structure of the deposits was evaluated employing X-ray diffraction technique. Morphology and chemical composition of the deposited alloy films were studied using scanning electron microscopy and energy-dispersive X-ray analysis, respectively. The results demonstrated that the rate of Ni-Mo-P deposition increases with increasing the ammonium molybdate concentration in the plating electrolyte up to 10 g l À1 . Also, the amount of Mo in the deposits increases with increasing the ammonium molybdate concentration up to 7.5 g l À1 , and the maximum Mo content in the film was 9.1 at.%. The catalytic activity of Ni-Mo-P/C alloy films has been evaluated towards electrooxidation of ethanol in 1.0 M NaOH solution by using cyclic voltammetry and chronoamperometry. The catalytic performance of the prepared anodes as a function of the amount of Mo was studied. The results showed an increase in the oxidation peak current density of ethanol with increasing the Mo at.% in the deposited alloy films. Additionally, Ni-Mo-P/C electrodes displayed significantly improved catalytic activity and stability towards electrooxidation of ethanol compared with that of Ni-P/C electrode.