TY - JOUR
T1 - Structural insights and electronic state analysis of PtNi nanowire catalysts by operando high-energy resolution fluorescence detection X-ray absorption spectroscopy
AU - Cao, Weijie
AU - Thakur, Neha
AU - Kumar, Mukesh
AU - Uchiyama, Tomoki
AU - Gao, Yunfei
AU - Tominaka, Satoshi
AU - Machida, Akihiko
AU - Watanabe, Toshiki
AU - Sato, Ryota
AU - Teranishi, Toshiharu
AU - Matsumoto, Masashi
AU - Imai, Hideto
AU - Sakurai, Yoshiharu
AU - Uchimoto, Yoshiharu
N1 - Publisher Copyright:
© 2024 The Royal Society of Chemistry.
PY - 2024/9/30
Y1 - 2024/9/30
N2 - Low-platinum alloy nanowire (NW) catalysts improve the performance of polymer electrolyte membrane fuel cells, but ultrafine PtNi-NW catalysts, particularly those with high Ni content, often experience significant Ni leaching during electrochemical processes. In this study, a Pt-rich surface layer was successfully formed on PtNi NWs through a simple post-annealing process. Pair distribution function (PDF) analysis revealed a Pt surface layer with a face-centered cubic (fcc) structure, along with internal body-centered tetragonal (bct) PtNi and fcc Ni phases. Operando X-ray absorption spectroscopy (XAS), including conventional and high-energy resolution fluorescence detection (HERFD) XAS, was used to investigate the catalysts' electronic states and structural changes under oxygen reduction reaction (ORR) conditions. The results showed that the Pt-rich surface layer of PtNi-NW/C catalysts, with its short Pt-Pt bond lengths, effectively suppresses Pt oxidation at high polarization potentials and restricts Ni leaching, leading to a significant increase in the ORR-specific activity of 2.07 mA cmPt−2, which is a 2.5- and 7-fold activity enhancement compared to Pt-NW/C and commercial Pt/C catalysts.
AB - Low-platinum alloy nanowire (NW) catalysts improve the performance of polymer electrolyte membrane fuel cells, but ultrafine PtNi-NW catalysts, particularly those with high Ni content, often experience significant Ni leaching during electrochemical processes. In this study, a Pt-rich surface layer was successfully formed on PtNi NWs through a simple post-annealing process. Pair distribution function (PDF) analysis revealed a Pt surface layer with a face-centered cubic (fcc) structure, along with internal body-centered tetragonal (bct) PtNi and fcc Ni phases. Operando X-ray absorption spectroscopy (XAS), including conventional and high-energy resolution fluorescence detection (HERFD) XAS, was used to investigate the catalysts' electronic states and structural changes under oxygen reduction reaction (ORR) conditions. The results showed that the Pt-rich surface layer of PtNi-NW/C catalysts, with its short Pt-Pt bond lengths, effectively suppresses Pt oxidation at high polarization potentials and restricts Ni leaching, leading to a significant increase in the ORR-specific activity of 2.07 mA cmPt−2, which is a 2.5- and 7-fold activity enhancement compared to Pt-NW/C and commercial Pt/C catalysts.
UR - http://www.scopus.com/inward/record.url?scp=85206537530&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85206537530&partnerID=8YFLogxK
U2 - 10.1039/d4ta03538k
DO - 10.1039/d4ta03538k
M3 - Article
AN - SCOPUS:85206537530
SN - 2050-7488
VL - 12
SP - 29843
EP - 29853
JO - Journal of Materials Chemistry A
JF - Journal of Materials Chemistry A
IS - 43
ER -
