Surface modification of commercial PtRu nanoparticles for methanol electro-oxidation

• Published in: Journal of power sources Vol. 240; pp. 122 - 130
• Main Authors: Kuo, Che-Wei, Lu, I-Te, Chang, Li-Chung, Hsieh, Yu-Chi, Tseng, Yuan-Chieh, Wu, Pu-Wei, Lee, Jyh-Fu
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.10.2013; Elsevier
• Subjects: Chemistry; Displacement reaction; Electrochemistry; Exact sciences and technology; General and physical chemistry; Kinetics and mechanism of reactions; Methanol electro-oxidation; Platinum; Ruthenium; X-ray absorption spectroscopy; Ruthenium; X-ray absorption spectroscopy; Platinum; Methanol electro-oxidation; Displacement reaction; Nanoparticle; Displacement; Surface treatment; Primary alcohol; X ray absorption spectrometry; Ruthenium alloy; Platinum alloy; Surface properties; Oxidation; Electrochemical reaction; Binary alloy; Methanol
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2013.04.001

The surfaces of commercially available PtRu nanoparticles (PtRu/C) have been successfully modified via a displacement reaction between the Ru atoms on the PtRu/C and the Pt ions in an aqueous hexachloroplatinic acid solution. The concentration of the hexachloroplatinic acid solution was deliberately formulated to allow for the formation of sub-monolayered Pt (Pt(1/16)) and monolayered Pt (Pt(1/8)) on the surface of PtRu/C. Material characterization, including X-ray diffraction patterns and transmission electron microscopy images, showed that the PtRu phases of the samples were identical but that the particle sizes increased slightly after the surface modification. Data from inductively coupled plasma mass spectrometry confirmed the deposition of Pt with negligible loss of Ru. X-ray absorption spectroscopy showed Pt-enriched surfaces, and the surface Pt content decreased in the order Pt(1/8) > Pt(1/16) > PtRu/C. Cyclic voltammetry and chronoamperometry were conducted for methanol electro-oxidation, and our results indicated impressive catalytic ability and carbon monoxide tolerance for Pt(1/16), followed by Pt(1/8) and PtRu/C. The mass activities of Pt(1/16) and Pt(1/8) increased 223% and 135% over that of PtRu/C. We attributed the observed improvements to the reduced amount of Ru on the PtRu surface, which resulted in an optimized PtRu ratio with enhanced catalytic ability. •Surface modification on commercially available PtRu nanoparticles to render a Pt-rich surface.•A displacement reaction between Ru atoms on the PtRu nanoparticles and Pt ions in an aqueous hexachloroplatinic acid solution.•Deliberate control over the severity of displacement reaction leads to a significant increment in mass activity for methanol electro-oxidation.