Iridium-Rhodium Nanoparticles for Ammonia Oxidation: Electrochemical and Fuel Cell Studies

Author(s)

Silva, Julio Cesar M. ; Assumpcao, Monica H. M. T. ; Hammer, Peter ; Neto, Almir O. ; Spinace, Estevam V. ; Baranova, Elena A.

• Document type: Journal article
• Source: CHEMELECTROCHEM; v. 4, n. 5, p. 1101-1107, MAY 2017.
• Web of Science Citations: 2

Abstract

This study reports the use of carbon-supported IrRh/C electrocatalysts with different iridium-to-rhodium atomic ratios (0 : 100, 50: 50, 70: 30, 90: 10, and 100: 0) for ammonia electro-oxidation (AmER) in alkaline media. The materials prepared by using the sodium borohydride method showed a mean diameter of 4.5, 4.8, 4.2, and 4.5 nm for Ir/C, Ir90Rh10/C, Ir70Rh30/C, and Ir50Rh50/C, respectively. According to electrochemical and fuel cell experiments, the Ir50Rh50/C catalyst was the most promising towards AmER. This catalyst, which consisted predominantly of the metallic Ir/Rh phases, showed a 500% higher current density and 55% higher maximum power than that obtained for Ir/C. After 8 h galvanostatic electrolysis, 93% of initial ammonia was degraded when using Ir50Rh50/C, whereas it was only 70% with Ir/C. The high activity of the Ir50Rh50/C is attributed to a synergic effect of two metals at this iridium-to-rhodium ratio, which enhances the kinetics of AmER contributing towards ammonia dehydrogenation at lower potentials. (AU)

• FAPESP's process: 13/01577-0 - Development of materials and degradation studies of electrocatalysts and supports for alkaline fuel cell
• Grantee: Júlio César Martins da Silva
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 14/09868-6 - Ammonia oxidation reaction and products determination using electrocatalysts and supports with enhanced durability and high catalytic activity
• Grantee: Júlio César Martins da Silva
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor