Innovative detection of methanol using a copper film–graphene–gold hybrid sensor engineered with 4-nitrothiophenol

We report the development of two novel methanol sensors based on copper film–supported graphene decorated with gold film. Electrode A (Cu/Gr-Au) was fabricated by depositing gold film on a graphene-coated copper film, while electrode B (Cu/Gr-Au-4-NTP) was prepared by further modifying this assembly with 4-nitrothiophenol (4-NTP). Advanced fabrication techniques enabled the preparation of these electrodes with excellent reproducibility and cost-effectiveness. Cyclic voltammetry measurements yielded a detection limit of 10 mM and a detection range of 10–485 mM for both electrode configurations, with sensitivities of 6.4 μA·mM−1·cm−2 for electrode A and 18.0 μA·mM−1·cm−2 for electrode B. Further electrochemical impedance spectroscopy studies (Z mod) confirmed a detection limit of 10 mM within a 10–485 mM range, with corresponding sensitivities of 0.147 Ω·mM−1·cm−2 for electrode A and 0.828 Ω·mM−1·cm−2 for electrode B. These findings demonstrate the enhanced performance of the 4-NTP functionalized electrode and underscore the potential of these innovative sensors for sensitive and rapid methanol detection compared to conventional systems. The enhanced performance of electrode B is attributed to the 4-NTP surface modification, which promotes methanol adsorption and facilitates electron transfer, resulting in superior sensitivity compared to electrode A. This work highlights the potential of integrating low-cost materials in sensor design to achieve high linearity, wide dynamic detection ranges, and rapid response times. The promising outcomes of these electrodes pave the way for further investigations into long-term stability, reproducibility, and system integration for real-time methanol monitoring applications.