Chemical Fluid Deposition of Pt-Based Bimetallic Nanoparticles on Multiwalled Carbon Nanotubes for Direct Methanol Fuel Cell Application

Abstract

A simple and green method of depositing platinum-based bimetallic nanoparticles (Pt−Ru, Pt−Cu, Pt−Au, Pt−Pd, and Pt−Ni) on multiwalled carbon nanotubes (MWCNTs) in supercritical fluid carbon dioxide (sc-CO2) is described. CO2-soluble metal precursors, such as metal acetylacetonates or hexafluoroacetylacetonates, were used in the experiments. Suitable temperature and pressure conditions for synthesizing each kind of bimetallic nanoparticle are studied. Characterizations of these nanocomposites, performed by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD), all confirmed their presence. These MWCNT-supported bimetallic nanoparticles have average sizes varying from 2.8 to 9.3 nm. The application of these nanocomposites is demonstrated by using them as electrocatalysts for direct methanol fuel cell (DMFC). Their electrochemical activities are studied by using cyclic voltammetry (CV), and their efficiency to oxidize methanol to carbon dioxide is at least 60% better than the MWCNT-supported monometallic Pt nanoparticle catalyst reported previously.

High Electrocatalytic Activity of Pt–Pd Binary Spherocrystals Chemically Assembled in Vertically Aligned TiO2 Nanotubes

“…In general, compared with monometallic catalysts, bimetallic catalysts often provide synergistic effects that can improve catalytic activity in electrochemical reactions [19] and efficiently avoid catalyst poisoning. [7,[41][42][43] Thus, when Pt-Pd binary catalysts are loaded into NTs, they may show better catalytic activity. According to the above guidlines, a highly dispersed bimetallic catalyst was synthesized by pulsed-current deposition (PCD) with the assistance of UC.…”

Nanotubular Mesoporous Bimetallic Nanostructures with Enhanced Electrocatalytic Performance

“…[24,25] Consequently, the ratio of current densities for these two anodic peaks, I f /I b , is generally used to evaluate the poison tolerance of Pt catalysts. [26,27] The observation of much higher I f /I b values on NM-Pt/Cu (1.55 vs. 0.81 on Pt/C) implicates that methanol molecules can be more effectively oxidized on NM-Pt/Cu during the forward potential scan, generating relatively less poisoning species as compared to Pt/C. To further explore the observed enhancement of the electrocatalytic activity and CO-tolerance, we carried out a CO electrostripping experiment.…”

Palladium Nanoparticles Loaded on Carbon Modified TiO2 Nanobelts for Enhanced Methanol Electrooxidation

“…At present, there are many efforts to enhance the electrocatalytic activity of Pd through the improvement of its geometrical and electronic properties. A common strategy is combining Pd with other metals forming alloys, such as PdSn, PdRu, and PdNi [13][14][15].…”

“…Alloy catalysts have a higher oxygen reduction activity than pure Pd [15], which help promote the oxidation of strongly adsorbed intermediates, such as the oxidation of CO ads to CO 2 . Another effective strategy is to prepare composite catalysts by coupling with semiconducting oxides (TiO 2 , SnO 2 and RuO 2 ) as support materials, which have been demonstrated to improve the catalytic activity and stability of Pd catalyst for alcohol electrooxidation [6,16,17].…”