Electrochemical Interfacial Modulation and Stability of Vitamin B6 by Silver Nanoparticles in Fluoride Electrolyte

Vitamin B6 (pyridoxine) is a biologically relevant micronutrient involved in numerous biochemical processes and may also participate in redox-related reactions. In the present study, the electrochemical behavior and stability of vitamin B6 were investigated in a 0.1 M sodium fluoride (NaF) electrolyte using platinum (Pt) as the working electrode, with particular emphasis on the effects of silver nanoparticles (Ag nanoparticles, 70 mg·L−1) on interfacial redox processes. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and UV-Vis spectroscopy were combined to characterize the molecular-electrode interface and the response of vitamin B6 under electrochemical stress. CV demonstrated that vitamin B6 substantially modifies the anodic and cathodic response of Pt, whereas incorporation of Ag nanoparticles partially attenuated the pronounced cathodic processes induced by vitamin B6. EIS revealed a progressive decrease in charge-transfer resistance from 2.19·103 Ω·cm2 in NaF to 1.81·103 Ω·cm2 after vitamin B6 addition and to 882 Ω·cm2 in the presence of Ag nanoparticles, accompanied by increased apparent interfacial capacitance and enhanced interfacial heterogeneity. UV-Vis spectroscopy further showed that Ag nanoparticles modify the optical response of the vitamin B6-containing system and exhibit a characteristic plasmonic absorption band. Under galvanostatic electrolysis at 50 mA·cm−2, vitamin B6 degradation followed apparent first-order kinetics, while the presence of Ag nanoparticles decreased the degradation rate constant from 4.70·10−3 to 3.02·10−3 min−1 and increased the apparent half-life from 147 to 229 min. These results indicate that Ag nanoparticles substantially influence the redox environment and electrochemical stability of vitamin B6, reducing its degradation under oxidative electrochemical conditions. The combined electrochemical and spectroscopic results provide new insight into the interfacial redox behavior of a biologically relevant vitamin in the presence of metallic nanoparticles and may contribute to understanding antioxidant-related molecular stability and redox processes in complex chemical environments.