Qiannan Wang

Porous Carbon-Supported Gold Nanoparticles for Oxygen Reduction Reaction: Effects of Nanoparticle Size

Porous carbon-supported gold nanoparticles of varied sizes were prepared using thiolate-capped molecular Au25, Au38, and Au144 nanoclusters as precursors. The organic capping ligands were removed by pyrolysis at controlled temperatures, resulting in good dispersion of gold nanoparticles within the porous carbons, although the nanoparticle sizes were somewhat larger than those of the respective nanocluster precursors. The resulting nanocomposites displayed apparent activity in the electroreduction of oxygen in alkaline solutions, which increased with decreasing nanoparticle dimensions. Among the series of samples tested, the nanocomposite prepared with Au25 nanoclusters displayed the best activity, as manifested by the positive onset potential at +0.95 V vs RHE, remarkable sustainable stability, and high numbers of electron transfer at (3.60-3.92) at potentials from +0.50 to +0.80 V. The performance is comparable to that of commercial 20 wt % Pt/C. The results demonstrated the unique feasibility of porous carbon-supported gold nanoparticles as high-efficiency ORR catalysts.

In situ preparation of multi-wall carbon nanotubes/Au composites for oxygen electroreduction

Multi-wall carbon nanotubes (CNTs)/Au nanocomposites have been prepared by the in situ reduction approach. The as-prepared hybrid materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The composition of the nanocomposites was fine tuned by varying the mass ratio of Au-to-CNTs. Among a series of samples tested, hybrid materials with a Au/carbon nanotubes (Au/CNTs) ratio = 1 : 2 demonstrated the best activity towards oxygen reduction reaction (ORR), as most positive onset potential, largest kinetic current density, highest amount of electron transfer and lowest H2O2 yields were obtained. Notably, the Au/CNTs also exhibited remarkable long-term durability higher than commercial Pt/C.