Induced electrochemical reduction of nitrates species on interface of Pt/MWCNTS prepared by vapor-phase impregnation-decomposition method

Abstract

Pt nanoparticles were supported on multi-wall carbon nanotubes (MWCNTs) and conventional C-Vulcan XC72 by a vaporphase impregnation-decomposition method using platinum acetylacetonate as precursor. Both types of carbon supports were impregnated with the precursor vapors at 180 °C and 3-7 Torr inside a horizontal quartz tube reactor. Then, they were heated at 400 °C to achieve precursor decomposition and subsequent formation of Pt nanoparticles. Carbon supports, and Pt precursor were mixed in several weight ratios. The Pt content was approximately 5, 10 and 25 wt.%. TEM observations revealed Pt particles ranging from 2.4 to 3.3 nm uniformly distributed on either nanotubes or conventional carbon support. The catalytic activity for nitrate electro-reduction (NER) was investigated in NaNO3 + NaOH solutions using Cycling Voltammetry (CV). The CV measurements showed a redox process from -0.7 to -1.0 V/SCE associated to the nitrate reduction process. It was found that Pt/MWCNTs materials display superior nitrate reduction activity than Pt/C-Vulcan XC72, even the comparable Pt decisive features. The superior activity seems to be associated to the inherent structural features of MWCNTs. Thus, Pt/MWCNTs are attractive materials for electrodes on the nitrate reduction process in alkaline medium aqueous.