Abstract:
1-D nanosized rod-like, wire-like, and tubular
α-MnO
2 (
xAu/
α-MnO
2,
x=2%,4%,8%,10%) were prepared using the hydrothermal and PVA-protected NaBH
4 reduction methods at different temperatures with KMnO
4 and/or MnSO
4 as Mn source, respectively. It is shown that the
α-MnO
2 in
xAu/
α-MnO
2 was tetragonal in crystal structure, surface area of
α-MnO
2 nanorods, nanowires, and nanotubes was in the range of 48.4-114.0 m
2/g. The 4%Au/
α-MnO
2 sample possessed the highest adsorbed oxygen species concentration and the best low-temperature reducibility, thus showing the highest catalytic activity: the
T50% and
T90% (temperatures required for achieving reactant conversions of 50% and 90%) were 11.4 and 16.3 ℃ for CO oxidation, and 210 and 225 ℃ for toluene oxidation at a space velocity of 20 000 mL/(g ·h), respectively. Based on the characterization results and activity data, it is concluded that the better low-temperature reducibility, higher oxygen adspecies concentration, highly dispersed Au NPs, and stronger interaction between Au NPs and MnO
2 nanorods were the main factors influencing the catalytic performance of 4%Au/
α-MnO
2.