Enhanced electroanalytical and energy storage performance via synergetic matrix of graphite-MMT composite electrode enriched with tin oxide as an electrochemically supportive mediator

Developing a dynamic, efficient, economical, and user-friendly electrode poses a significant challenge to electrochemists; as such, electrodes are vital for fabricating electrochemical devices, including supercapacitors and bio/chemical sensors. This research aimed to combine graphite, tin oxide, and MMT to fabricate an electrode (G-SnO₂-MMT-CE), obtaining a synergetic matrix where tin oxide acts as an electrochemically supportive mediator that performs better in electroanalytical and energy storage purposes. G-SnO₂-MMT-CE exhibits a high flexural strength, which is 1.63×106 Nm^-2 and 4.4×10^-3 Ω m resistivity. The ideal voltammogram shape and better sensitivities to analytes, exhibiting a similar sensitivity to both Fe²⁺/Fe³⁺ and [Fe(CN)₆]₄-/[Fe(CN)₆]₃- redox systems, which is ~1.0A m mol^-1, reveal G-SnO₂-MMT-CE potential as a working electrode to analyte detection. Aniline electropolymerization on G-SnO₂-MMT-CE resulted in an interwoven polyaniline nanofiber network, which accounts for a low serial resistance (2.53 Ω) and charge transfer resistance (4.25 Ω). The Nyquist plot supported the PANI-G-SnO₂-MMT-CE pseudo-capacitive behavior, which is mainly from PANI microstructural heterogeneity. According to the CV method, a supercapacitor cell constructed by combining two identical PANI-G-SnO₂-MMT-CE electrodes exhibits a high specific capacitance of 881 F g⁻¹ at 5 mV s⁻¹, which is consistent with the capacitance obtained from the galvanostatic charge–discharge measurement (921 F g⁻¹). Even after 1000 cycles, the supercapacitor cell maintains a high columbic efficiency (>99%), which explains the low energy loss during the cycling process, resulting in great energy efficiency and cyclic stability.
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