Nickel foam-based composite electrodes for electrooxidation of methanol

Tungsten carbide/porous carbon core–shell nanocomposites as a catalyst support for methanol oxidation

The Pt–WC@C demonstrates higher electrochemical activity, which could be attributed to the better dispersed Pt on WC which leads to the improved synergistic effect between WC and Pt.

Surface science and electrochemical analysis of nickel foams

Open-pore nickel (Ni) foams are characterized using surface science and electrochemical techniques. A scanning electron microscopy analysis reveals interconnected Ni struts that generate small and large pores of ca. 50 and 500 μm in size, respectively. An X-ray photoelectron spectroscopy (XPS) analysis of the surface-chemical composition of the Ni foams shows that there are oxidized and metallic sections within their surfaces despite being prepared by sintering in an oxidizing atmosphere at a high temperature and being stored in moist air. The ratio of the areas of oxidized and metallic sections is evaluated using XPS data. Chemical etching of the Ni foams results in removal of the native surface oxide/hydroxide without altering the three-dimensional structure; it also increases the roughness (R) of the surfaces of Ni struts giving rise to an increase in the electrochemically active surface area (Aecsa). Thermal treatment of Ni foams in an H2(g) atmosphere at 500 °C reduces the native surface oxide/hydroxide but does not increase R or Aecsa. Electrochemical behavior of the Ni foams is examined in 0.5 M aqueous KOH solution using cyclic-voltammetry (CV) and electrochemical impedance spectroscopy (EIS). As-received, chemically etched, thermally reduced and electro-oxidized Ni foams generate distinct CV profiles; their features are assigned to oxidized and metallic surface states. The observations made on the basis of XPS measurements are corroborated by the results of CV analyses. The application of CV and XPS or EIS allows in situ determination of Aecsa and the specific surface area (As) of the chemically etched and thermally reduced Ni foams. The values of As determined on the basis of joint CV and XPS measurements are 227 ± 74 and 149 ± 48 cm(2) g(-1) for the etched and reduced Ni foams, respectively. The values of As determined on the basis of CV, XPS and EIS measurements are 241 ± 80 and 160 ± 23 cm g(-1) for the etched and reduced Ni foams, respectively.

Electrocatalytic hydrodechlorination of 4-chlorobiphenyl in aqueous solution using palladized nickel foam cathode

The electrocatalytic hydrodechlorination of 4-chlorobiphenyl on palladized nickel foam with high porous structure in an aqueous solution containing MeOH, bromide of hexadecyltrimethylammonium (CTAB), sodium acetate, and acetic acid were investigated in a membrane-separated flow-through cell. The Pd/Ni foam electrode was prepared by electroless deposition method, on which the Pd particles dispersed finely over Ni foam surface indicated by SEM-EDX analysis. The effects of current density, organic cosolvent, initial concentration, temperature, and flow rate on the hydrodechlorination of 4-chlorobiphenyl were examined. Methanol was among the best cosolvents and was used in preferential concentration of 50 vol%. Moderate current density (e.g., 2.23 mA cm(-2)), relatively high initial concentration, temperature, and flow rate were beneficial to improve the hydrodechlorination of 4-chlorobiphenyl. The current efficiencies for the conversion of 1mM 4-MCB decreased with increasing current density and range from 37.2% at 0.74 mA cm(-2) to 14.1% at 5.21 mA cm(-2) after 20 min electrolysis cut. Under the optimized conditions, 1mM of 4-MCB could be removed rapidly with the rate of 94.6% after 2h electrolysis, which gave current efficiencies and energy consumptions in range of 8.1-24.6% and 1.7-5.2 kW h kg(-1), respectively.