Electrochemical determination of the degree of atomic surface roughness in Pt–Ni alloy nanocatalysts for oxygen reduction reaction. Issue 2 (13th October 2020)

• Record Type: Journal Article
• Authors: Jeon, Tae‐Yeol; Yu, Seung‐Ho; Yoo, Sung J.; Park, Hee‐Young; Kim, Sang‐Kyung
• Is Part Of: Carbon energy. Volume 3:Issue 2(2021)
• Page Start: 375
• Page End: 383
• Publication Date: 2020-10-13
• Subjects: electrocatalyst -- fuel cell -- oxygen reduction reaction -- Pt–Ni -- surface roughness; Carbon -- Periodicals; Carbon dioxide industry -- Periodicals; Power resources -- Research -- Periodicals; Energy industries -- Periodicals; Power resources -- Research; Energy industries; Carbon dioxide industry; Carbon; Electronic journals; Periodicals; 620.193
• DOI: 10.1002/cey2.82
• Languages: English
• ISSNs: 2637-9368

Abstract

Abstract: Pt–Ni alloy nanocrystals with Pt‐enriched shells were prepared by selective etching of surface Ni using sulfuric acid and hydroquinone. The changes in the electronic and geometric structure of the alloy nanoparticles at the surface were elucidated from the electrochemical surface area, the potential of zero total charge (PZTC), and relative surface roughness, which were determined from CO‐ and CO2 ‐displacement experiments before and after 3000 potential cycles under oxygen reduction reaction conditions. While the highest activity and durability were achieved in hydroquinone‐treated Pt–Ni, sulfuric acid‐treated one showed the lower activity and durability despite its higher surface Pt concentration and alloying level. Both PZTC and Q CO 2 / Q CO ratio (desorption charge of reductively adsorbed CO2 normalized by COad ‐stripping charge) depend on surface roughness. In particular, Q CO 2 / Q CO ratio change better reflects the roughness on an atomic scale, and PZTC is also affected by the electronic modification of Pt atoms in surface layers. In this study, a comparative study is presented to find a relationship between surface structure and electrochemical properties, which reveals that surface roughness plays a critical role to improve the electrochemical performance of Pt–Ni alloy catalysts with Pt‐rich surfaces. Graphical abstract: This study suggests a new approach to calculating the relative surface roughness of Pt‐based alloy nanoparticles. Hydroquinone and sulfuric acid treatments dissolve surface Ni atoms in Pt–Ni alloy nanocrystals and form Pt‐enriched shells with different levels of surface roughness. Hydroquinone treatment generates a smoother surface, compared with sulfuric acid. A lower roughness contributes to a durability enhancement during an oxygen reduction reaction.