Luo Tianhong

Electrocatalytic Performance of Pd Catalyst Supported on Macropore Carbon for Oxidation of Formic Acid

The electrocatalytic performances of a Vulcan XC-72 carbon black supported Pd (Pd/XC) catalyst and a macroporous carbon supported Pd (Pd/MC) catalyst for formic acid oxidation in a direct formic acid fuel cell were investigated and compared. This was carried out using X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) spectroscopy, Raman spectroscopy, and electrochemical techniques. The cyclic voltammograms indicate that the main peak potentials for the oxidation of formic acid at the Pd/XC and Pd/MC catalyst electrodes are similar and they are located at about 0.15 V. However, the peak current density of the Pd/MC catalyst electrode is about 30% larger than that of the Pd/XC catalyst electrode. The chronoamperometric curves indicate that the peak current density at the Pd/MC catalyst electrode at 6000 s is about 38% larger than that at the Pd/XC catalyst electrode. These results show that the electrocatalytic activity and stability of the Pd/MC catalyst for the oxidation of formic acid are better than those of the Pd/XC catalyst. Because the average size and relative crystallinity of the Pd particles in the two catalysts are similar, the reason for the better electrocatalytic performance of the Pd/MC catalyst could be only attributed to its larger pore diameter and higher conductivity because of its high extent of MC graphitization.

Preparation of Carbon Supported Ir-Co Catalyst and Its Electrocatalytic Performance for Ammonia Oxidation

The Ir-Co/C catalyst was prepared via a liquid phase reduction method.X-ray diffraction(XRD) and transmission electron microscope(TEM) results indicated that Co atoms enter the crystal lattice of Ir and form the Ir-Co alloy as evidenced by the lattice constriction of Ir and the aggregation of Ir particles could be suppressed.The electrochemical investigation illustrated that comparing with the Ir/C catalyst,the onset potential of the NH3 oxidation is negatively shifted about 100 mV,the peak current density is increased about 100% and the electrocatalytic stability is also increased at the Ir-Co/C catalyst.In addition,the sensitivity and the detection limit of NH3 are decreased at the Ir-Co/C catalyst.The results illustrate that the electrocatalytic performance of the Ir-Co/C catalyst for the NH3 oxidation is obviously better than that of the Ir/C catalyst.Thus,the Ir-Co/C catalyst has a potential application in the electrochemical NH3 sensor.

Electrocatalytic Performance of Ir Catalyst Supported on Macropore Carbon for Ammonia Oxidation

Macroporous carbon supported Ir(Ir/MC) and Vulcan XC-72 carbon supported Ir(Ir/XC) catalysts were prepared respectively.Based on the characterization of the catalysts using the energy dispersive spectroscopy,X-ray diffraction spectroscopy and Raman spectroscopy,the electrocatalytic performances of the two catalysts for the ammonia oxidation were investigated.It was found that the peak current density of the ammonia oxidation at the Ir/MC catalyst electrode is 38.7% larger than that at the Ir/XC catalyst electrode and the electrocatalytic stability of the Ir/MC catalyst is better than that of the Ir/XC catalyst.Because the average size and the relative crystallinity of the Ir particles in the Ir/MC catalyst is similar to that in the Ir/XC catalyst,the above results can be attributed to the larger pore size and porosity as well as the higher conductivity due to the high graphitization extent of MC.