Selective Deposition of Gold Nanoparticles on or Inside Carbon Nanotubes and Their Catalytic Activity for Preferential Oxidation of CO

Abstract

Gold nanoparticles have been deposited on three kinds of carbon nanotubes (CNTs), including nitrogen‐doped CNTs, by three different methods, namely, impregnation, organometallic decomposition, and deposition–precipitation. The choice of the gold precursor, the support, and the preparation procedure is critical for the control of the size and location (on or inside the nanotubes) of the gold nanoparticles. These catalysts were tested for the selective oxidation of CO in a hydrogen‐rich atmosphere. We have shown that the use of nitrogen‐doped CNTs as a support permits one to reach much higher activity and selectivity at low temperaturethan with the other CNT supports. This catalyst also shows a good stability under reaction conditions without detectable sintering.

High performance of carbon nanotubes confining gold nanoparticles for selective hydrogenation of 1,3-butadiene and cinnamaldehyde

“…CNTs have been widely studied as supports for nanoscopic metal catalysts, although those were generally deposited on the outer surface [11][12][13][14][15][16][17][18][19][20][21][22][23]. A few studies [16,18,20,23] show the reactions catalyzed by metal NPs encapsulated inner cavity of the CNTs.…”

“…A few studies [16,18,20,23] show the reactions catalyzed by metal NPs encapsulated inner cavity of the CNTs. The earlier studies have revealed that Pd NPs could be introduced inside multi-walled CNTs by an incipient wetness impregnation technique [16,18].…”

“…Au/CNTs and Au/C catalysts were prepared by the gold sol method with polyvinyl alcohol (PVA) for the stabilizing agent and NaBH 4 for the reducing agent, which led to small Au particle sizes as reported in the earlier works [23]. Specifically, 1.0 mL PVA solution (2.91 mg mL À1 ) was mixed with 50 mL 0.25 mM AuCl À 4 solution for 1 h under vigorous stirring.…”

“…Very few reports have revealed that gold NPs could selectively fill inside the CNTs [21,22]. Only one example to our best knowledge has addressed the effect of gold NPs deposited on the outside or inside the tubes on catalytic activity for the oxidation of CO in H 2 [23]; however, the authors found that almost no catalytic activity for gold NPs filled in the CNTs cavity irrespective of the small average diameter (3.5 nm) or large diameter (18 nm) of gold NPs [23].…”

One-dimensional nitrogen-containing carbon nanostructures

“…Au NPs have been deposited on NCNTs by Castillejos et al [455] using deposition-precipitation method starting from a water/methanol solution of sodium tetrachloroaurate(III) that is added to NCNTs, and the resulting precipitate was dried at 100…”