• Fu, Chun Chieh
• Hsieh, Chien Te
• Mallick, Bikash Chandra
• Gu, Siyong
• Kihm, Kenneth D.
• Gandomi, Yasser Ashraf

Abstract

<p>An efficient infrared (IR)-assisted technique is developed to synthesize highly amidized graphene quantum dots (GQDs) as a metal-free catalyst for electrochemically detecting hydrogen peroxide. Through the IR-assisted pyrolysis of urea and citric acid at different chemical ratios, the GQDs with very high amidation level (N/C atomic ratio: 23–46 at.%) are synthesized, composed of pyrrolic/pyridinic N, graphitic N, and N-oxide functionalities. Through various electrochemical diagnostics, it is confirmed that highly amidized GQD electrodes enable high catalytic activity toward H₂O₂ reduction. The catalytic cycle includes the adsorption of H₂O₂ and two-stage charge transfer steps on highly amidized GQD catalyst, where the substitutional N atoms (i.e., pyridinic N) at the edge of carbon network provide additional electroactive sites for adsorbing H₂O₂. The amperometric investigation followed by a rigorous linear regression analysis confirms a high selectivity of 1.83 μA mM⁻¹ cm⁻² toward H₂O₂ detection within the concentration range of 0.5–40 mM. The major attributes of the GQD catalytic electrodes include high sensitivity, wide detection range, fast response time, and superior selectivity. Accordingly, the robust design of GQDs developed in this work paves the way for engineering highly selective catalyst as a robust electrochemical sensor for non-enzymatic H₂O₂ detection at ultra-low concentrations.</p>

Topics

• pyrolysis
• impedance spectroscopy
• Carbon
• Hydrogen
• quantum dot