Silver Nanoparticle/Multiwalled Carbon Nanotube Hybrid as an Efficient Electrocatalyst for the Oxygen Reduction Reaction in Alkaline Medium

Abstract

A straightforward approach is employed to synthesize silver nanoparticle/multiwalled carbon nanotube (Ag/MWNTs) hybrids through the direct reduction of silver nitrate in the presence of MWNTs, where Ag nanoparticles capped with tris(hydroxymethyl)phosphine oxide (d = 2.9 nm) are uniformly deposited on MWNTs. The as-synthesized Ag/MWNTs hybrids exhibit high catalytic activity toward the oxygen reduction, which increases with the loading amount of Ag nanoparticles. Rotating disk electrode and rotating ring-disk electrode analyses further indicate that the Ag/MWNTs hybrids follow the same fourelectron pathway towards the oxygen reduction reaction as the Pt/C catalyst, and the Ag/MWNTs hybrid (22.8 wt.%) manifests comparable catalytic activity to the 20 % Pt/C catalyst, together with superior long-term stability and methanol tolerance, demonstrating the potential application on direct methanol fuel cells as an effective oxygen reduction catalyst.

Construction of MWNT supported ultra-small Ag@MnO2 nanoparticles for the ORR and Al–air batteries

“…The mass ratio of Mn to the total weight was 11.27 wt%, 0 wt% and 17.94 wt%, respectively. The loading content of Ag in Ag@MnO 2 /MWNTs was only 10.03 wt%, below the 22.8 wt% in our previous work 13 and the Ag/Mn mass ratio was 0.89.…”

“…[10][11][12] However, the Ag nanoparticles are easily aggregated due to high surface energy, and are oen loaded onto the surface of conductive carriers to improve the surface area of the active site of the catalytic material, such as graphene, carbon nanotubes, and porous carbon. 10,12 Moreover, the required load quality of Ag is relatively high; for the Ag/ multi-walled carbon nanotube (MWNT) catalyst prepared in our previous work, 13 the Ag load should reach 22.8% to achieve the requisite catalytic activity, which increases the cost. In recent years, manganese oxide (MnO 2 ) has been widely studied for its moderate catalytic activity, low cost and environmental friendliness, and it has become one of the most promising ORR materials in alkaline solutions.…”