Fuel Cells Catalysts Assembled With Nitrogen-doped Carbon Nanohorn And Metal Nanoclusters

(1) We report the use of nitrogen-doped single-wall carbon nanohorns as a promising support material for the anode electrocatalysts of DMFCs. Compared to PtRu/C catalysts (home made and commericial catalysts) , PtRu/NSWCNHs catalyst exhibits the highest MA, If/Ib value and the lowest onset potential, which are desired for MOR. The MOR mass activity of PtRu/NSWCNHs is 2.5 and 1.7 times as high as that of PtRu/C-JM and PtRu/C-HM, respectively. The MOR specific activity of PtRu/NSWCNHs is 1.8 times as high as that over PtRu/C-HM having similar Pt/Ru atomic ratios, specific electrochemical surface areas and particle sizes of PtRu NPs.PtRu/NSWCNHs catalyst maintains the higher current density during all stages of chronoamperometric measurements and the current density value is nearly twice as high as that of others. In view of its excellent catalytic activity for MOR, great tolerance to carbonaceous intermediates, and convenient preparation process, PtRu/NSWCNHs is a promising anode catalyst for DMFCs and PEMFCs.(2)A highly durable and active nanocomposite cathode catalyst (Pt/NSWCNH) was assembled with "unprotected" Pt nanoclusters and nitrogen-doped single-wall carbon nanohorns (NSWCNH)as building blocks by a convenient process. The specific catalytic activity and mass catalytic activity for the oxygen reduction reaction over Pt/NSWCNH is 1.60 and 1.75 times as high as those over a commercial Pt/C catalyst, respectively. There was no obvious loss in the catalytic activity of Pt/NSWCNH after potential cycling from 0.6 to 1.1 V versus RHE for 15000 cycles at 30 ?, under the oxidizing conditions for the electrochemically catalytic reduction of O2. TEM characterization results revealed that, during the accelerated aging tests, Pt nanoparticles in Pt/NSWCNH are more stable than that in Pt/C-JM, showing a low increase in the particle size.(3) Novel covalent porphyrin/multi-walled carbon nanotubes (MWNTs) nanohybrids was synthesized successfully by the reaction of aryl bromide on the surface of MWNTs, which was introduced by the nitrene reaction, with 5-p-hydroxyphenyl-10,15,20-triphenyl-porphyrin(MHTPP) and 5-p-aminophenyl-10,15,20-triphenyl-porphyrin (MATPP). The nanohybrid was characterized by FT-IR, Raman, UV-vis, TGA and TEM. From the FT-IR and TGA spectrum, it was confirmed that the porphyrin had linked to the MWNTs covalently. The Raman and absorption spectroscopy data showed that the electronic properties of modified MWNTs were mostly retained, without damaging their one-dimensional electronic properties. The spectroscopy of fluorescence revealed that the two kinds of porphyrins were nearly quenched by the MWNTs,indicating that this covalently modified method and the conjugated linker facilitated an effective energy or electron transfer between the excited porphyrin moiety and the extended p-system of MWNTs, which was favorable for many potential uses, especially in light-harvesting systems.