In situ processed tungsten carbide/carbon black-supported platinum electrocatalysts for enhanced electrochemical stability and activity

Abstract

High performance electrocatalysts have been intensively studied to reduce the usage of expensive platinum-group metals and to obtain excellent electrochemical durability. Herein, we introduce a very promising processing technique based on the low-temperature in situ synthesis of tungsten carbide nanoparticles with carbon under a highly energetic arc plasma atmosphere prior to the deposition of Pt nanoparticles. There is no external supply of carbon for this synthesis since the carbon black (CB) support acts as a source of carbon. Multiple phases, including WC, W₂C, and W_1−xC, were found to exist by the electron diffraction analytical simulation technique. The final structure of Pt/W_xC/CB showed significantly better performance in terms of electrocatalytic activities, such as electrochemically active surface area, methanol oxidation activity, mass activity, CO tolerance, and 10 000 cycle-accelerated durability test, compared to those of the commercial reference sample containing more Pt. The origin of the enhancement was understood to be associated primarily with the presence of W_xC itself, a smaller scale of well dispersed W_xC nanoparticles, reduced oxidation of Pt, and graphitization of the CB matrix.