Electrochemical reduction of oxygen molecules can produce H2O2, which is an important chemical for a green and sustainable society; therefore, the development of catalysts for this reaction is necessary. We propose mesoporous nitrogen-doped carbon prepared from (1-methyl-1H-pyrrole-2-yl)methanol in the presence of a mesoporous SiO2 template (KIT-6). The nitrogen content of the resulting carbon can be controlled in the range of 0–10 at. % and all prepared samples have well-ordered mesopores with diameters of 3.4–4.0 nm. Electrochemical studies indicate the present materials have high catalytic activities with high selectivity toward H2O2 over 90%. Such high selectivity toward H2O2 is probably due to good mass transport in the catalyst layer, which is enhanced by the mesoporous structure.
28 October 2009 in The Journal of Physical Chemistry C
The hybrid direct carbon fuel cell (HDCFC) with solid oxide and molten carbonate binary electrolyte merges solid oxide fuel cell (SOFC) and molten carbonate fuel cell technologies to achieve direct conversion of solid carbon to electric power. The purpose of this study is to investigate in detail the electrochemistry of the oxidation of solid carbon in the carbon/carbonate slurry in the HDCFC. A planar test cell has been fabricated employing conventional SOFC materials and a eutectic carbonate mixture of lithium carbonate and potassium carbonate. The HDCFC with a model fuel, carbon black XC-72R, shows very high open circuit voltages (OCVs), approximately 1.5 V at 550–700 °C, especially after a high temperature operation at 900 °C, where carbonate decomposes to O2− and CO2. The carbon/carbonate slurry increases the active reaction zone from a two-dimensional Ni/YSZ anode to a three-dimensional slurry and significantly enhances the carbon oxidation. The high OCV is probably due to the low activity of CO2 in the slurry, which results from the recombination of CO2 and O2−. Gaseous products were analysed using an online gas chromatograph, and CO2 and CO were detected, with their selectivity found to be dependent on temperature. Solid carbon is electrochemically oxidised to CO2 and the final distribution of the products is dominated by the equilibrium of the Boudouard reaction (C + CO2 ⇄ 2CO).