H.B. Hassan

Electrooxidation of methanol and ethanol on carbon electrodeposited Ni–MgO nanocomposite

Abstract Ni–MgO nano-composites were prepared on carbon anodes by electrodeposition from a nickel Watts bath in the presence of fine MgO reinforcement particles. Their performance as electrocatalysts for the oxidation of methanol and ethanol in alkaline medium was investigated and compared with that of carbon coated pure Ni (Ni/C). The chemical composition, phase structure, and surface morphology of the deposited nano-composites were studied by energy dispersive X-ray spectroscopy, X-ray diffractometry, and scanning electron microscopy, respectively. Different electrochemical techniques were used to estimate the catalytic activity of the prepared electrocatalyst anodes, including cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). The Ni/C electrocatalyst alone exhibited remarkably low catalytic activity and poor stability toward the electrooxidation process. The inclusion of MgO significantly promoted the catalytic activity of the Ni catalyst for the alcohol electrooxidation and enhanced its poisoning resistance. The EIS results confirmed those of CV and revealed a lower charge transfer resistance and enhanced roughness for the Ni–MgO/C nano-composite electrodes compared with those of Ni/C.

Corrosion Performance of Copper - Diamond Composites in Different Aqueous Solutions

In the present work copper/diamond composites, such as (Cu-10 Vf % diamond uncoated, Cu-30 Vf % diamond uncoated, Cu-10 Vf % diamond coated NiCrB and Cu-30 Vf % coated NiCrB) as heat sink materials have been fabricated using powder metallurgy and electroless techniques. The copper powder used in this study has been fabricated using electroless technique and the diamond powder was electroless coated with NiCrB film. The copper powder have been mixed with the uncoated or coated diamond particles, milled, compacted and sintered at 900°C in a hydrogen atmosphere. The corrosion behavior of the copper composite samples has been investigated in 0.6 M NaCl, 0.1 M HCl and 0.5 M NaOH solutions using potentiodynamic polarization anodic and cathodic Tafel lines and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) linking with energy dispersive X-ray spectroscopy (EDS) has been used to investigate the surface morphology and the chemical composition of the coated layer. The results of the corrosion test illustrated that the coated and uncoated Cu/diamond composites suffer from corrosion to a different extent in various electrolytes. The lowest corrosion rate in all the studied media was recorded for Cu-10 Vf % D coated NiCrB composite compared with the massive copper or uncoated composite samples.