Nitrogen-Doped Reduced Graphene Oxide for Electrochemical Sensing Applications ^†

Graphene-based derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), have gained significant attention in the field of electrochemical sensors [1]. These materials offer several advantages, including a time-efficient and cost-effective synthesis procedure and unique chemical, physical, and electronic properties [2]. rGO-based materials, in particular, possess a high surface area, chemical stability, and electrical conductivity [3]. However, despite these favorable characteristics, the development of rGO-based sensors with high sensitivity and rapid response times remains a challenge. One of the promising strategies to meet this challenge is the doping of rGO using heteroatoms. This approach involves introducing certain atoms (e.g., N, B, P, or S) into the graphene lattice, which can modify the structural and electrochemical rGO properties [4]. Therefore, this study focuses on the synthesis and structural characterization of N-doped rGO-based materials and their application to the electrochemical sensing of dopamine and H₂O₂. rGO modification with nitrogen species was achieved using two different synthesis approaches. To functionalize the rGO surface with a cationic Bismarck Brown dye, a hydrothermal synthesis method was employed. Also, the rGO surface was modified using gaseous ammonia at temperatures of 950 °C or 850 °C for 8 or 4 h, respectively. The obtained materials were characterized by different methods (XPS, BET, SEM, and Raman spectroscopy). Electrochemical measurements, such as cyclic voltammetry and chronoamperometry, were used to evaluate the obtained samples toward dopamine or H₂O₂ detection. The results demonstrated that various nitrogen species, including pyridinic-N, pyrrolic-N, and quaternary-N, were detected in the N-doped rGO. Moreover, it was observed that the amount and type of N-species introduced into the rGO surface contribute to the improved performance of the sensing platform, enabling the sensitive and selective detection of analytes.