Triphenylphosphine Oxide: A Versatile Covalent Functionality for Carbon Nanotubes

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Single-walled carbon nanotubes (SWCNTs) offer great potential but require functionalization for diverse applications.
• Covalent modification of SWCNTs is key to expanding their utility.
• Triphenylphosphine oxide (Ph₃P(O)) is an underutilized surface functionality for SWCNTs.

Purpose of the Study:

• To report the covalent linkage of Ph₃P(O) to SWCNTs.
• To develop a method for synthesizing Ph₃P(O)-functionalized SWCNTs (SWCNT-P) with tunable Ph₃P(O) content.
• To investigate the structural, spectroscopic, and electrochemical properties of SWCNT-P.

Main Methods:

• Synthesis of novel phosphine oxide-functionalized diaryliodonium salts for Ph₃P(O) transfer.
• Characterization using Raman, IR, UV/Vis-NIR, XPS, and TGA.
• Electron microscopy for structural analysis and de-bundling assessment.
• Electrochemical studies to evaluate ion-sensing properties.

Main Results:

• Successful covalent attachment of Ph₃P(O) to SWCNTs, creating SWCNT-P with controlled Ph₃P(O) loading.
• Robust and molecularly distributed Ph₃P(O) linkage confirmed by multiple spectroscopic techniques.
• Improved SWCNT de-bundling, leading to superior dispersibility and processability.
• SWCNT-P demonstrated sensitivity to Li⁺, Na⁺, and K⁺ ions, with electrochemical responses correlating to ion Lewis acidity.

Conclusions:

• A new synthetic route for Ph₃P(O)-functionalized SWCNTs (SWCNT-P) has been established.
• SWCNT-P exhibits enhanced dispersibility and processability due to Ph₃P(O) functionalization.
• SWCNT-P serves as a responsive nanomaterial platform capable of transducing ion Lewis acidity into electrochemical signals.