Determination of H+ ion diffusion in Ti3C2-rGO glucose sensor

The diffusion of generated H + ions in glucose sensing process is critical for the sensitivity of sensor. Although many glucose sensors assembled by two dimensional (2D) materials (MXene, graphene, MoS 2 et al.) have been extensively studied, the detailed analyses about the diffusion of H + ions are still rarely reported. Herein, hybrid Ti 3 C 2 -rGO film is fabricated by electrostatic self-assembly utilizing the 2D Ti 3 C 2 and graphene sheets to focus on the H + ion’s diffusion dynamic properties related to the sensing performance. Through controlling the graphene content, this hybrid Ti 3 C 2 -rGO film provide the effective H + ion diffusion channels. Based on the comprehensive analyses of cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS), the corresponding localized conduction and enzymatic reaction at interfaces between the Ti 3 C 2 -rGO electrodes and glucose solution were investigated. According to the Warburg impedance in Nyquist plot from EIS, it is certified that the H + ion diffusion in low frequency range may play a significant role in the sensing mechanism of the glucose sensor. Moreover, the relationship derived from the interaction including interlayer spacing, H + ion diffusion and the sensing performance further reveal the H + ion diffusion as the dominant origin of the enhanced glucose sensitivity. This analysis will provide fundamental insight into the electrode structures assembled with 2D materials to optimize the sensor design in terms of ion transport dynamics.