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The influence of the surface modification of multi-walled carbon nanotubes (MWCNT) with nitrogen-containing compounds on the performance of 40 wt% Pt/MWCNT catalysts in the oxygen electroreduction reaction (ORR) was investigated using a rotating disk electrode (RDE) at 10-35 °C in 0.1 M HClO 4 as electrolyte in electrochemical cell, and in a hydrogen-oxygen polymer electrolyte membrane fuel cell (PEMFC) at 82 °C. The catalysts were characterized by low-temperature nitrogen adsorption, XPS, TEM, gas-phase CO titration, electrooxidation of the adsorbed CO monolayer, and cyclic voltammetry. It was shown that the modification of MWCNT with melamine-formaldehyde resin leads to the surface nitrogen concentration up to 8.3 at.% (CNT-MF sample). The 40 wt% Pt/CNT-MF catalyst with 0.1 mg cm −2 Pt loading on the cathode showed a good performance in PEMFC (~ 0.61 W cm −2) and a high utilization ratio (0.84) of Pt in membrane electrode assembly as compared to Pt/CNT catalyst (~ 0.37 W cm −2 and utilization of 0.29). The higher power density of nitrogen-modified catalysts was ascribed to a higher utilization of Pt in the electrode layer.

Activated carbons were prepared from rice husk carbonized in the fluidized catalysts bed reactor. Using the different activating agents, samples with BET surface area in the range from 540 to 3060 m 2 /g were achieved. Using sodium or potassium carbonates results in the BET surface area up to 1400 m 2 /g. Hydroxides of sodium or potassium yield the samples with the higher BET surface area (up to 3060 m 2 /g). Textural peculiarities of the carbons were studied by the adsorption of nitrogen at 77 K and of carbon dioxide at 273 K. As active materials for supercapacitors, the porous carbon samples were examined by cyclic voltammetry and chronopotentiometry in galvanostatic mode in 1 M H 2 SO 4 as the electrolyte using home-made three-electrode electrochemical glass cell. Gravimetric capacitance of the carbons is linearly proportional to the BET surface area and reaches 230 and 196 F/g at discharge current density of 0.2 and 1 A/g, respectively, for the samples with the highest surface area.

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Nickel is a promising electrocatalyst for hydrogen electrode reactions in alkaline media. Its electrocatalytic activity for hydrogen oxidation and evolution reactions can be enhanced when its surface is partially covered by Ni (hydr)oxides or by associating it with Cu. In this work, the influence of the NaOH concentration on the hydrogen electrode kinetics on various Ni electrodes is investigated. On metallic Ni, the electrocatalytic activity (measured as an exchange current density normalized to the surface area of Ni) is almost constant between pH 12 and 14, whereas it decreases by a factor of two on partially oxidized Ni and on the NiCu/C electrode. Analyzing the current potential curves with the help of microkinetic modeling reveals that the Had and OHad binding energies on Ni do not depend on pH, whereas the rate constants of the Volmer and Heyrovsky reactions decrease with pH. The pH effect on the electron transfer elementary act is briefly discussed in the framework of a quantum mechanical theory.