Abstract:
Nitrogen-doped carbon nanotubes (NCNTs) were synthesized by treating HNO3-oxidized carbon
nanotubes (CNTs) in an NH3 flow at different temperatures. PtRu nanoparticles were decorated over
NCNTs. The PtRu catalysts were prepared by an impregnation–reduction method from metal chloride
precursors with a total metal loading of about 10 wt%. The electrocatalytic activity with respect to
methanol oxidation was studied using electrochemical and scanning electrochemical microscopy
(SECM) measurements. Transmission electron microscopy revealed the spherical shape and narrow
particle size distribution of the PtRu particles over NCNTs with average particle sizes of 3–5 nm. A
detailed X-ray photoelectron spectroscopy study was performed to quantitatively identify different
nitrogen functional groups and to evaluate their role in the observed enhanced catalytic activity towards
methanol oxidation. The determination of the local electrocatalytic activity of the proposed catalyst
towards methanol oxidation and simultaneous evaluation of the intermediates produced during
methanol oxidation were achieved using SECM. Density functional theory studies were performed to
understand the adsorption sites of methanol and intermediates on different reactive sites and to
investigate possible reaction mechanisms.
