Core–shell Silica–Ruthenium hexacyanoferrate nanoparticles modified electrode as efficient electrocatalyst for riboflavin detection and oxygen evolution reaction

An innovative core–shell nanoparticle system comprising a silica (SiO
2
) core and a ruthenium hexacyanoferrate
(RuHCF) shell was successfully synthesized. The structural and optical behaviour of the resulting SiO
@RuHCF
nanoparticles (NPs) were characterized by UV–visible spectroscopy. The surface morphology and nanoscale
architecture were further elucidated through field-emission scanning electron microscopy (FESEM) and high-
resolution transmission electron microscopy (HRTEM), confirming the successful encapsulation of RuHCF on
the silica core. The electrochemical functionality of the synthesized SiO
@RuHCF-NPs was explored by incorporating

them into a paraffin wax-impregnated graphite electrode (PIGE) via mechanical immobilization,
forming an electroactive redox mediator system. The modified electrode was characterized by voltammetric
methods and demonstrated excellent electrocatalytic activity toward the riboflavin reduction. The developed
riboflavin sensor exhibited a fast response time of 4 s, a low detection limit of 1.4 × 10
2
7
M, a broad linear range
of 4.3–2600
μM, high sensitivity 0.204 μA/μM, and showed good stability and repeatability. These features
highlight the sensor's potential for practical applications. Furthermore, the modified electrode also facilitated
oxygen evolution in alkaline medium, achieving an optimal current density of 10 mA cm
at overpotential of
just 560 mV from the thermodynamic potential of 1.23 V, indicating its promise for electrocatalytic applications.
2
2