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Title: Chemical Strategies for Enhancing Activity and Charge Transfer in Ultrathin Pt Nanowires Immobilized onto Nanotube Supports for the Oxygen Reduction Reaction

Multiwalled carbon nanotubes (MWNTs) represent a promising support medium for electrocatalysts, especially Pt nanoparticles (NPs). The advantages of using MWNTs include their large surface area, high conductivity, as well as long-term stability. Surface functionalization of MWNTs with various terminal groups, such as -COOH, -SH, and -NH 2, allows for rational electronic tuning of catalyst–support interactions. But, several issues still need to be addressed for such systems. Over the course of an electrochemical run, catalyst durability can decrease, due in part to metal NP dissolution, a process facilitated by the inherently high surface defect concentration within the support. Second, the covalent functionalization treatment of MWNTs adopted by most groups tends to lead to a loss of structural integrity of the nanotubes (NTs). In order to mitigate for all of these issues, we have utilized two different attachment approaches (i.e., covalent versus noncovalent) to functionalize the outer walls of pristine MWNTs and compared the catalytic performance of as-deposited ultrathin (<2 nm) 1D Pt nanowires with that of conventional Pt NPs toward the oxygen reduction reaction (ORR). Our results demonstrated that the electrochemical activity of Pt nanostructures immobilized onto functionalized carbon nanotube (CNT) supports could be dramatically improved by using ultrathin Pt nanowiresmore » (instead of NPs) with noncovalently (as opposed to covalently) functionalized CNT supports. Spectroscopic evidence corroborated the definitive presence of charge transfer between the metal catalysts and the underlying NT support, whose direction and magnitude are a direct function of (i) the terminal chemistry as well as (ii) the attachment methodology, both of which simultaneously impact upon the observed electrocatalytic performance. Specifically, the use of a noncovalent π–π stacking method coupled with a -COOH terminal moiety yielded the highest performance results, reported to date, for any similar system consisting of Pt (commercial NPs or otherwise) deposited onto carbon-based supports, a finding of broader interest toward the fabrication of high-performing electrocatalysts in general.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ; ORCiD logo [4]
  1. State Univ. of New York (SuNY), Stony Brook, NY (United States). Dept. of Chemistry
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials
  3. State Univ. of New York (SUNY), Stony Brook, NY (United States). School of Marine and Atmospheric Sciences
  4. State Univ. of New York (SuNY), Stony Brook, NY (United States). Dept. of Chemistry; Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Division
Publication Date:
Report Number(s):
BNL-113311-2016-JA
Journal ID: ISSN 1944-8244; R&D Project: PM037; KC0201030; TRN: US1701156
Grant/Contract Number:
SC00112704; SC-00112704
Type:
Published Article
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 8; Journal Issue: 50; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; charge transfer; functionalized carbon nanotubes; noncovalent attachment; oxygen reduction reaction; Pt ultrathin nanowires
OSTI Identifier:
1336964
Alternate Identifier(s):
OSTI ID: 1338606