Quantifying Surface Area of Nanosheet Graphene Oxide Colloid Using a Gas-Phase Electrostatic Approach

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Accurate characterization of graphene oxide (GO) surface area is crucial for its applications.
• Traditional methods like BET analysis can be time-consuming and require significant sample preparation.
• A need exists for rapid, precise, and low-sample-volume techniques for GO surface area quantification.

Purpose of the Study:

• To develop and validate a novel, facile gas-phase electrostatic approach for quantifying the equivalent surface area of graphene oxide (GO) colloids on a number basis.
• To establish a correlation between mobility diameter and surface area for GO colloids.
• To demonstrate the speed and efficiency of this new method compared to existing techniques.

Main Methods:

• Utilized electrospray-differential mobility analysis (ES-DMA) coupled with a condensation particle counter (CPC) and an aerosol surface area analyzer (ASAA).
• Determined mobility diameter-based distribution and equivalent surface area (SA) of GO colloids with varying aspect ratios.
• Developed an ultrafast measurement by directly coupling electrospray (ES) with ASAA and CPC, achieving results in 2 minutes per sample.

Main Results:

• Established a correlation SA ∝ d_p,m^2.0, consistent with 2D image analysis.
• Achieved an equivalent surface area measurement of GO at approximately 202 ± 7 m² g^-1.
• Demonstrated comparability to Brunauer-Emmett-Teller (BET) surface area (∼240 ± 59 m² g^-1) with high precision.

Conclusions:

• The gas-phase electrostatic approach provides a rapid, precise, and low-sample-volume method for GO surface area determination.
• This technique eliminates the need for elaborate drying processes, simplifying GO characterization.
• This study represents the first use of an aerosol-based electrostatic coupling technique for high-precision, number-basis equivalent surface area measurement of graphene oxide.