Electrocatalytic nitrate reduction on well-defined surfaces of tin-modified platinum, palladium and platinum-palladium single crystalline electrodes in acidic and neutral media

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2017-09, Vol.800, p.46-53
• Main Authors: Kato, Masaru, Okui, Manabu, Taguchi, Satoshi, Yagi, Ichizo
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Bimetals; Catalysis; Catalytic activity; Crystal structure; Crystallinity; Denitrification; Electrocatalysis; Electrocatalysts; Electrodes; Groundwater; Nitrate reduction; Nitrates; Palladium; Platinum; Platinum base alloys; Pollutants; Reduction; Single crystalline electrodes; Surface alloying; Tin base alloys
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2017.01.020

Nitrate anion is one of the main nitrogen-containing-pollutants in groundwater and can be removed using denitrification systems including electrocatalytic systems. Herein we report on electrocatalytic nitrate reduction catalyzed on tin-modified single crystalline electrodes of palladium, platinum and palladium-platinum alloy in acidic and neutral media. We have prepared electrodes with the (111) surface or the (100) surface and modified their surface with tin. Cyclic voltammetry of the electrodes has revealed that the tin-modified alloy (trimetallic) electrodes show higher electrocatalytic activity than the tin-modified platinum or palladium (bimetallic) electrodes, and the catalytic reaction is more efficiently catalyzed on the (100) surface rather than the (111) surface. The tin-modified PdPt(100) electrode shows the highest catalytic activity in acidic media as well as in neutral media. X-ray photoelectron spectroscopy suggests that metallic tin forms on the (100) surface, but divalent tin species on the (111) surface, indicating that a surface alloy of tin may form on the (100) surface, resulting in enhancement of the electrocatalytic activity. Our findings suggest that design and preparation of ternary metallic electrodes with the (100) surface will pave the way to the development of practical systems on electrocatalytic denitrification. [Display omitted] •Tin-modified single crystalline Pd, Pt and PdPt alloy electrodes are prepared.•Electrocatalytic nitrate reduction occurs efficiently on the (100) surface.•A surface alloy may form for Sn/PdPt(100), revealed by using XPS.•Sn/PdPt(100) is highly active for electrocatalytic nitrate reduction.•Sn/PdPt(100) shows the catalytic activity in not only acidic but also neutral media.