The development of highly efficient catalysts for cathodes remains an important objective of fuel cell research. Here, we report Co3O4 nanoparticles assembled on a polypyrrole/graphene oxide electrocatalyst （C...The development of highly efficient catalysts for cathodes remains an important objective of fuel cell research. Here, we report Co3O4 nanoparticles assembled on a polypyrrole/graphene oxide electrocatalyst （Co3O4/Ppy/GO） as an efficient catalyst for the oxygen reduction reaction （ORR） in alkaline media. The catalyst was prepared via the hydrothermal reaction of Co2＋ ions with Ppy-modified GO. The GO, Ppy/GO, and Co3O4/Ppy/GO were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The incorporation of Ppy into GO nanosheets resulted in the formation of a nitrogen-modified GO po-rous structure, which acted as an efficient electron-transport network for the ORR. With further anchoring of Co3O4 on Ppy/GO, the as-prepared Co3O4/Ppy/GO exhibited excellent ORR activity and followed a four-electron route mechanism for the ORR in alkaline solution. An onset potential of -0.10 V vs. a saturated calomel electrode and a diffusion limiting current density of 2.30 mA/cm^2 were achieved for the Co3O4/Ppy/GO catalyst heated at 800 ℃; these values are comparable to those for noble-metal-based Pt/C catalysts. Our work demonstrates that Co3O4/Ppy/GO is highly active for the ORR. Notably, the Ppy coupling effects between Co3O4 and GO provide a new route for the preparation of efficient non-precious electrocatalysts with hierarchical porous structures for fuel cell applications.展开更多
The thermal stability of N 2 on Mo(100) surface was studied by Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and thermal desorption spectroscopy (TDS). It was found that when the Mo(100) su...The thermal stability of N 2 on Mo(100) surface was studied by Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and thermal desorption spectroscopy (TDS). It was found that when the Mo(100) surface was exposed to 1?500 L of N 2 and then heated up to 1?100 K, a good model Mo(100) c(2×2)N structure could be obtained. Heated to 1?300 K, the structure began to be destroyed and the c(2×2) LEED pattern disappeared. The N atoms recombined into molecules which desorbed from the surface at 1?300 K.展开更多
基金supported by the National Natural Science Foundation of China(21373042)~~
文摘The development of highly efficient catalysts for cathodes remains an important objective of fuel cell research. Here, we report Co3O4 nanoparticles assembled on a polypyrrole/graphene oxide electrocatalyst （Co3O4/Ppy/GO） as an efficient catalyst for the oxygen reduction reaction （ORR） in alkaline media. The catalyst was prepared via the hydrothermal reaction of Co2＋ ions with Ppy-modified GO. The GO, Ppy/GO, and Co3O4/Ppy/GO were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The incorporation of Ppy into GO nanosheets resulted in the formation of a nitrogen-modified GO po-rous structure, which acted as an efficient electron-transport network for the ORR. With further anchoring of Co3O4 on Ppy/GO, the as-prepared Co3O4/Ppy/GO exhibited excellent ORR activity and followed a four-electron route mechanism for the ORR in alkaline solution. An onset potential of -0.10 V vs. a saturated calomel electrode and a diffusion limiting current density of 2.30 mA/cm^2 were achieved for the Co3O4/Ppy/GO catalyst heated at 800 ℃; these values are comparable to those for noble-metal-based Pt/C catalysts. Our work demonstrates that Co3O4/Ppy/GO is highly active for the ORR. Notably, the Ppy coupling effects between Co3O4 and GO provide a new route for the preparation of efficient non-precious electrocatalysts with hierarchical porous structures for fuel cell applications.
文摘The thermal stability of N 2 on Mo(100) surface was studied by Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and thermal desorption spectroscopy (TDS). It was found that when the Mo(100) surface was exposed to 1?500 L of N 2 and then heated up to 1?100 K, a good model Mo(100) c(2×2)N structure could be obtained. Heated to 1?300 K, the structure began to be destroyed and the c(2×2) LEED pattern disappeared. The N atoms recombined into molecules which desorbed from the surface at 1?300 K.
