Carbon Nanodots as Electrocatalysts towards the Oxygen Reduction Reaction

Abstract

Electrocatalysts perform a key role in increasing efficiency of the oxygen reduction reaction (ORR) and as a result, efforts have been made by the scientific community to develop novel and cheap materials that have the capability to exhibit low ORR overpotentials and allow the reaction to occur via a 4 electron pathway, thereby mimicking as close as possible to traditionally utilised platinum. In that context, two different types of carbon nanodots (CNDs) with amide (CND‐CONH2) and carboxylic (CND‐COOH) surface groups, have herein been fabricated and shown to exhibit excellent electrocatalytic activity towards the ORR in acid and basic media (0.1 M H2SO4 and 0.1 M KOH). CND surface modified carbon screen‐printed electrodes allow for a facile electrode modification and enabling the study of the CNDs electrocatalytic activity towards the ORR. CND‐COOH modified SPEs are found to exhibit improved ORR peak current and reduced overpotential by 21.9 % and 26.3 %, respectively compared to bare/unmodified SPEs. Additionally, 424 μg cm−2 CND‐COOH modified SPEs in oxygenated 0.1 M KOH are found to facilitate the ORR via a near optimal 4 (3.8) electron ORR pathway. The CNDs also exhibited excellent long‐term stability and tolerance with no degradation being observed in the achievable current with the ORR current returning to the baseline level within 100 seconds of exposure to a 1.5 M solution of methanol. In summary, the CND‐COOH could be utilised as a cathodic electrode for PEMFCs offering greater stability than a commercial Pt electrode.

Carbon Dots and Graphene Quantum Dots in Electrochemical Biosensing

“…The few applications of CDs in electrochemical biosensing described to date are mainly focused on the electrocatalytic properties of these nanoparticles towards O 2 [31] and H 2 O 2 reduction, exploited for the biosensing of glucose [32,33] or H 2 O 2 [34] and the sensing of dopamine [35], 2,4,6-trinitrotoluene [36], patulin [37], and glucose [38]. In the particular case of electrochemical affinity biosensors, only one example involving the use of CDs as electrode modifiers in the preparation of a DNA sensor to detect single gene mutations has been reported so far [1].…”

The Novel Nanomaterials Based Biosensors and Their Applications

“…Concerning the employment of CNDs for electrochemical biosensors, it should be highlighted that despite the previously mentioned advantages, very few attempts to incorporate CNDs into electrodes are reported. Reporting the application of CNDs in electrochemical sensors are focused on the electrocatalytic properties of this nanomaterial toward oxygen reduction [109], biomedical application [110], exploited for glucose biosensing [111] and DNA sensing [112].…”

Contribution of Carbon Dot Nanoparticles in Electrocatalysis: Development in Energy Conversion Process

“…They found a prominent O 2 reduction peak at 0.45 V vs. RHE for the O 2 saturated KOH solution with an onset potential of ORR at 0.94 V. They obtained a two electron pathway of O 2 reduction to hydrogen peroxide. Martínez-Periñán et al [36] reported the effect of surface functional groups on ORR in acidic and alkaline medium. They fabricated amide (CD-CONH 2 ) and carboxylic acid functionalized (CD-COOH) CND particles and examined their electrocatalytic properties towards ORR in acidic and alkaline medium.…”