Title: Sub-4 nm PtZn Intermetallic Nanoparticles for Enhanced Mass and Specific Activities in Catalytic Electrooxidation Reaction

Abstract

Atomically ordered intermetallic nanoparticles (iNPs) have sparked considerable interest in fuel cell applications by virtue of their exceptional electronic and structural properties. However, the synthesis of small iNPs in a controllable manner remains a formidable challenge because of the high temperature generally required in the formation of intermetallic phases. Here in this paper we report a general method for the synthesis of PtZn iNPs (3.2 ± 0.4 nm) on multiwalled carbon nanotubes (MWNT) via a facile and capping agent free strategy using a sacrificial mesoporous silica (mSiO₂) shell. The as-prepared PtZn iNPs exhibited ca. 10 times higher mass activity in both acidic and basic solution toward the methanol oxidation reaction (MOR) compared to larger PtZn iNPs synthesized on MWNT without the mSiO₂ shell. Density functional theory (DFT) calculations predict that PtZn systems go through a “non-CO” pathway for MOR because of the stabilization of the OH* intermediate by Zn atoms, while a pure Pt system forms highly stable COH* and CO* intermediates, leading to catalyst deactivation. Experimental studies on the origin of the backward oxidation peak of MOR coincide well with DFT predictions. Moreover, the calculations demonstrate that MOR on smaller PtZn iNPs is energetically more favorable than larger iNPs,more » due to their high density of corner sites and lower-lying energetic pathway. Therefore, smaller PtZn iNPs not only increase the number but also enhance the activity of the active sites in MOR compared with larger ones. This work opens a new avenue for the synthesis of small iNPs with more undercoordinated and enhanced active sites for fuel cell applications.« less

Authors:

Qi, Zhiyuan ^[1]; Xiao, Chaoxian ^[1]; Liu, Cong ^[2]; Goh, Tian Wei  ^[1];

• Search DOE PAGES for author "Goh, Tian Wei"
• Search DOE PAGES for ORCID "0000-0002-4141-3392"

Zhou, Lin ^[3]; Maligal-Ganesh, Raghu ^[1]; Pei, Yuchen ^[1]; Li, Xinle ^[1]; Curtiss, Larry A.  ^[4];

• Search DOE PAGES for author "Curtiss, Larry A."
• Search DOE PAGES for ORCID "0000-0001-8855-8006"

Huang, Wenyu  ^[5]

• Search DOE PAGES for author "Huang, Wenyu"
• Search DOE PAGES for ORCID "0000-0003-2327-7259"

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+ Show Author Affiliations

1. Iowa State Univ., Ames, IA (United States). Dept. of Chemistry
2. Argonne National Lab. (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Division
3. Ames Lab., Ames, IA (United States)
4. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division
5. Iowa State Univ., Ames, IA (United States). Dept. of Chemistry; Ames Lab., Ames, IA (United States)

Publication Date:

Wed Mar 08 00:00:00 EST 2017

Research Org.:

Ames Laboratory (AMES), Ames, IA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)

OSTI Identifier:

1355406

Report Number(s):

IS-J-9261
Journal ID: ISSN 0002-7863; TRN: US1702295

Grant/Contract Number:  

CHE-1607305; AC02-07CH11358; AC02-06CH11357

Resource Type:

Accepted Manuscript

Journal Name:

Journal of the American Chemical Society

Additional Journal Information:

Journal Volume: 139; Journal Issue: 13; Journal ID: ISSN 0002-7863

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY