Title: Performance characteristics for oxygen reduction reaction of nanostructured Pt_100−xCo_x supported on Vulcan carbon and carbon nanotubes catalysts

Authors: Nguyen Luong Nhat Phu; Ha The An; Tran Van Man; Nguyen Thi Phuong Thoa; Le Van Thang

Addresses: Faculty of Chemistry, Applied Physical Chemistry Laboratory, VNUHCM – University of Science, 227 Nguyen Van Cu, District 5, Ho Chi Minh City, Vietnam ' Faculty of Chemistry, Applied Physical Chemistry Laboratory, VNUHCM – University of Science, 227 Nguyen Van Cu, District 5, Ho Chi Minh City, Vietnam ' Faculty of Chemistry, Department of Physical Chemistry and Applied Physical Chemistry Laboratory, VNUHCM – University of Science, 227 Nguyen Van Cu, District 5, Ho Chi Minh City, Vietnam ' Faculty of Chemistry, Department of Physical Chemistry and Applied Physical Chemistry Laboratory, VNUHCM – University of Science, 227 Nguyen Van Cu, District 5, Ho Chi Minh City, Vietnam ' Materials Technology Laboratory, VNUHCM – University of Technology, 268 Ly Thuong Kiet, Distric 10, Ho Chi Minh City, Vietnam

Abstract: The catalytic activity for oxygen reduction reaction (ORR) of Pt_100−xCo_x (100 ≥ x ≥ 0) catalysts supported on Vulcan carbon XC-72R (VC), raw carbon nanotubes (rCNTs) and purified carbon nanotubes (pCNTs) was investigated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The materials were synthesised by chemical reduction using NaBH₄ as reducing agent. The TEM, XRD and XRF data were consistent with the formation of Pt-Co alloy nanoparticles having size ranging from 1.00 nm to 14.00 nm. The linear sweep voltammograms showed that Pt₈₀Co₂₀/VC, which has the least coverage of oxygenated species, was the best catalyst for ORR with its onset potential of 0.574 V. From the slope of Koutecky-Levich plots for ORR using Pt_100−xCo_x/VC materials as catalysts, it was found that the overall electron transfer number ranged from 3 to 4, which led to the suggestion of H₂O₂ formation as an intermediate of the ORR. Carbon nanotubes after treatment (pCNTs) exhibited better activity for ORR compared to raw CNTs. However, Pt₈₀Co₂₀ catalyst supported on Vulcan carbon showed an enhancement in catalytic activity higher than that on CNTs; therefore, the replacement of CNTs to Vulcan carbon did not improve the performance of the catalysts.

Keywords: carbon nanotubes; nanotechnology; oxygen reduction reaction; platinum-cobalt catalyst; rotating disk electrodes; voltammetry; Vulcan carbon; platinum; cobalt; nanostructures; CNTs.

DOI: 10.1504/IJNT.2015.067901

International Journal of Nanotechnology, 2015 Vol.12 No.5/6/7, pp.434 - 446

Published online: 08 Mar 2015 *

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