Radiation-induced synthesis of carbon-supported niobium oxide nanoparticle catalysts and investigation of heat treatment conditions to improve the oxygen reduction reaction activity

Abstract

Carbon-supported niobium oxide nanoparticle catalysts were synthesized for the oxygen reduction reaction (ORR) in acidic media. These catalysts were prepared using a 60 Co gamma-ray and heat-treated with polyacrylonitrile. Carbon black powder or multi-walled carbon nanotube (CNT) was used as the support for the niobium nanoparticle. Nb 2 O 5 nanoparticles with low crystallinity were fine and well dispersed on the carbon support in the as-irradiated samples. The loading amount of niobium increased with the absorbed dose, which indicated that niobium nanoparticles were produced by the irradiation. The as-irradiated composite nanoparticles were heat-treated under an H 2 atmosphere (5 %) or a mixed atmosphere of H 2 (2 %) and O 2 (0.05 %) to introduce active sites. The ORR activities were significantly enhanced by the heat treatment. Furthermore, the ORR activities were improved by using multi-walled CNT as the support.

Improvement of ORR Activity of Monoclinic Zirconium Oxides by Fe and F Co-addition for PEFC Cathodes

“…[3][4][5][6][7][8][9] Group 4 and 5 metal (Ti, Zr, Nb, and Ta)-based oxides have been studied with particular attention to their stability because they are abundant and highly stable in acidic solutions. [10][11][12][13][14][15][16][17][18][19] Although these metal oxides are insulators with large band gaps, it is possible to generate catalytic activity in ORR using the following approach: 20,21 (1) Forming ORR active sites on the oxide surface by modifications such as doping with different atoms or introducing oxygen vacancies. (2) Constructing electron conduction paths to ORR active sites.…”