Project Title

Immobilization of Electrocatalytically Active Gold Nanoparticles on Nitrogen-Doped Carbon Fiber Electrodes

Authors' Affiliations

Department of Chemistry, College of Arts and Sciences, East Tennessee State University, Johnson City, TN.

Location

AUDITORIUM ROOM 137A

Start Date

4-12-2019 1:40 PM

End Date

4-12-2019 1:55 PM

Faculty Sponsor’s Department

Chemistry

Name of Project's Faculty Sponsor

Dr. Gregory Bishop

Type

Oral Presentation

Classification of First Author

Graduate Student-Master’s

Project's Category

Electrochemistry

Abstract Text

Immobilization of Electrocatalytically Active Gold Nanoparticles on Nitrogen-Doped Carbon Fiber Electrodes

ABSTRACT

Recently, immobilization of single metal nanoparticles on nanometer-sized electrodes has been demonstrated as a means to electrochemically probe the relationship between nanoparticle structure and function. Such studies of individual, isolated nanoparticles enable investigation of electrochemical behavior and electrocatalytic properties in the absence of complicating factors like interparticle distance and nanoparticle loading that are typically associated with collections of particles distributed on electrode supports. However, interpretation of electrochemical data obtained from single nanoparticle immobilization experiments can also be difficult since the underlying nanoelectrode platform can sometimes contribute to the measured current or the immobilization strategy may have adverse effects on electron transfer. Here we report immobilization of gold nanoparticles on relatively catalytically inert carbon fiber ultramicro- and nanoelectrodes through a modification method based on recently reported soft nitriding process found to be effective in attaching ligand-free ultrasmall noble metal catalysts to activated carbons. X-ray photoelectron spectroscopy results reveal that the nitriding of carbon fibers provides 3.5 times increase in surface nitrogen content, introducing mostly pyridinic and amine nitrogen groups. The nitrogen-containing surface sites proved to be beneficial to the deposition of gold nanoparticles (AuNPs), as sodium borohydride reduction of tetrachloroaurate resulted in attachment of AuNPs on nitrided carbon fiber ultramicroelectrodes (N-CF-UMEs) in as little as 10 seconds while immobilization of AuNPs on unmodified CF-UMEs required at least 12 hours. A recently reported electrochemical method was employed to characterize immobilized AuNPs, and AuNP size was found to be directly related to deposition time. AuNPs immobilized on N-CF-UMEs also exhibited electrocatalytic activity towards methanol oxidation. Reduction of electrode size will enable this strategy to be employed to investigate electrochemical behavior of individual gold nanoparticles, while the ligand-free nature of the immobilized particles also provides the opportunity to investigate effects of surface capping agents on electrocatalytic properties.

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Apr 12th, 1:40 PM Apr 12th, 1:55 PM

Immobilization of Electrocatalytically Active Gold Nanoparticles on Nitrogen-Doped Carbon Fiber Electrodes

AUDITORIUM ROOM 137A

Immobilization of Electrocatalytically Active Gold Nanoparticles on Nitrogen-Doped Carbon Fiber Electrodes

ABSTRACT

Recently, immobilization of single metal nanoparticles on nanometer-sized electrodes has been demonstrated as a means to electrochemically probe the relationship between nanoparticle structure and function. Such studies of individual, isolated nanoparticles enable investigation of electrochemical behavior and electrocatalytic properties in the absence of complicating factors like interparticle distance and nanoparticle loading that are typically associated with collections of particles distributed on electrode supports. However, interpretation of electrochemical data obtained from single nanoparticle immobilization experiments can also be difficult since the underlying nanoelectrode platform can sometimes contribute to the measured current or the immobilization strategy may have adverse effects on electron transfer. Here we report immobilization of gold nanoparticles on relatively catalytically inert carbon fiber ultramicro- and nanoelectrodes through a modification method based on recently reported soft nitriding process found to be effective in attaching ligand-free ultrasmall noble metal catalysts to activated carbons. X-ray photoelectron spectroscopy results reveal that the nitriding of carbon fibers provides 3.5 times increase in surface nitrogen content, introducing mostly pyridinic and amine nitrogen groups. The nitrogen-containing surface sites proved to be beneficial to the deposition of gold nanoparticles (AuNPs), as sodium borohydride reduction of tetrachloroaurate resulted in attachment of AuNPs on nitrided carbon fiber ultramicroelectrodes (N-CF-UMEs) in as little as 10 seconds while immobilization of AuNPs on unmodified CF-UMEs required at least 12 hours. A recently reported electrochemical method was employed to characterize immobilized AuNPs, and AuNP size was found to be directly related to deposition time. AuNPs immobilized on N-CF-UMEs also exhibited electrocatalytic activity towards methanol oxidation. Reduction of electrode size will enable this strategy to be employed to investigate electrochemical behavior of individual gold nanoparticles, while the ligand-free nature of the immobilized particles also provides the opportunity to investigate effects of surface capping agents on electrocatalytic properties.