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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 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 (mSiO(2)) 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, due to theirmore » 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:
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Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1374430
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the American Chemical Society; Journal Volume: 139; Journal Issue: 13
Country of Publication:
United States
Language:
English

Citation Formats

Qi, Zhiyuan, Xiao, Chaoxian, Liu, Cong, Goh, Tian Wei, Zhou, Lin, Maligal-Ganesh, Raghu, Pei, Yuchen, Li, Xinle, Curtiss, Larry A., and Huang, Wenyu. Sub-4 nm PtZn Intermetallic Nanoparticles for Enhanced Mass and Specific Activities in Catalytic Electrooxidation Reaction. United States: N. p., 2017. Web. doi:10.1021/jacs.6b12780.
Qi, Zhiyuan, Xiao, Chaoxian, Liu, Cong, Goh, Tian Wei, Zhou, Lin, Maligal-Ganesh, Raghu, Pei, Yuchen, Li, Xinle, Curtiss, Larry A., & Huang, Wenyu. Sub-4 nm PtZn Intermetallic Nanoparticles for Enhanced Mass and Specific Activities in Catalytic Electrooxidation Reaction. United States. doi:10.1021/jacs.6b12780.
Qi, Zhiyuan, Xiao, Chaoxian, Liu, Cong, Goh, Tian Wei, Zhou, Lin, Maligal-Ganesh, Raghu, Pei, Yuchen, Li, Xinle, Curtiss, Larry A., and Huang, Wenyu. Wed . "Sub-4 nm PtZn Intermetallic Nanoparticles for Enhanced Mass and Specific Activities in Catalytic Electrooxidation Reaction". United States. doi:10.1021/jacs.6b12780.
@article{osti_1374430,
title = {Sub-4 nm PtZn Intermetallic Nanoparticles for Enhanced Mass and Specific Activities in Catalytic Electrooxidation Reaction},
author = {Qi, Zhiyuan and Xiao, Chaoxian and Liu, Cong and Goh, Tian Wei and Zhou, Lin and Maligal-Ganesh, Raghu and Pei, Yuchen and Li, Xinle and Curtiss, Larry A. and Huang, Wenyu},
abstractNote = {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 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 (mSiO(2)) 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, 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.},
doi = {10.1021/jacs.6b12780},
journal = {Journal of the American Chemical Society},
number = 13,
volume = 139,
place = {United States},
year = {Wed Mar 22 00:00:00 EDT 2017},
month = {Wed Mar 22 00:00:00 EDT 2017}
}