Time-Scale-Resolved Capacitance and Relaxation-Time Analysis of Glucose Electrooxidation on NiO Electrodes

Area of Science:

• Electrochemistry
• Materials Science
• Sensor Technology

Background:

• Electrochemical impedance spectroscopy (EIS) is crucial for studying interfacial charge transfer.
• Transforming impedance data into alternative domains can reveal masked electrochemical processes.
• Non-enzymatic glucose sensors are vital for diabetes monitoring.

Purpose of the Study:

• To investigate glucose oxidation on NiO using electrochemical capacitance spectroscopy (ECS) and distribution of relaxation times (DRT).
• To demonstrate DRT as a time scale domain transduction method complementing ECS for mechanistic insights.
• To explore the potential of DRT and ECS for designing advanced non-enzymatic glucose sensors.

Main Methods:

• Preparation and structural characterization of NiO via thermal decomposition.
• Application of electrochemical capacitance spectroscopy (ECS) to separate double layer and pseudocapacitive contributions.
• Utilizing distribution of relaxation times (DRT) to analyze time-resolved electrochemical steps and kinetics.

Main Results:

• ECS showed increasing glucose concentration enhances pseudocapacitance and reduces charge transfer resistance.
• ECS revealed a linear increase in low-frequency capacitance with glucose concentration, while double-layer capacitance remained constant.
• DRT identified two processes (OH- adsorption and glucose oxidation) with distinct relaxation times, showing selectivity for glucose over other molecules.

Conclusions:

• DRT critically complements ECS, offering powerful mechanistic insights into electrochemical systems.
• The combined ECS and DRT approach provides a detailed understanding of glucose oxidation on NiO.
• This study establishes DRT as a valuable tool for the advanced design of selective non-enzymatic glucose sensors for diabetes management.