Graphitic carbon coupled poly(anthraquinone) for proton shuttle flow-in-a-cell application

Area of Science:

• Electrochemistry
• Materials Science
• Microfluidics

Background:

• Coupled electron and proton transport are crucial for non-gassing electro-osmotic pumps (EOP).
• Electrode kinetics, specifically electron transfer rates, directly influence pump performance and flow.
• Synthesized graphitic carbon covalently coupled to poly(anthraquinone) (PAQ) offers potential for improved electrode materials.

Purpose of the Study:

• To investigate the effect of graphitic carbon content on the electrochemical properties of PAQ-based electrodes.
• To determine the electron-transfer kinetics and optimize electrode composition for enhanced electro-osmotic flux.
• To evaluate the performance of these novel electrodes in microfluidic devices.

Main Methods:

• Synthesis of graphitic carbon covalently coupled to poly(anthraquinone) (PAQ) with varying compositions.
• Electrochemical characterization using cyclic voltammetry and electrochemical impedance spectroscopy.
• Analysis of electron-transfer rate constants (k_s) and transfer coefficients (α) via Laviron plots.
• Performance evaluation of electro-osmotic pumps (EOP) in a flow-in-a-cell setup.

Main Results:

• A linear dependency was observed between electron-transfer kinetics (k_s) and graphitic carbon content.
• The highest electron-transfer rate constant (k_s) achieved was 0.67 s^-1 for the 15PAQ electrode.
• The optimized 15PAQ electrode demonstrated a maximum electro-osmotic flux of approximately 40 μL min^-1 cm^-1 V^-1.
• Proton shuttle facilitated reversible flow linearly dependent on k_s values in EOP with identical electrodes.

Conclusions:

• A balanced combination of graphitic carbon and PAQ is essential for high-performance electrode materials.
• These optimized electrodes show significant promise for applications in microfluidic devices and energy storage/conversion.
• The study highlights the critical role of electrode kinetics in the efficiency of electro-osmotic pumps.