Synergistically Enhanced Peroxidase-like Activity of FeSe₂/rGO Nanohybrids: Kinetic, Mechanistic, and Molecular...

FeSe₂/rGO nanohybrids were prepared via in situ one-pot synthesis using the hydrothermal method and were assessed for their potential for peroxidase-like activity. Structural and morphological analysis using FE-SEM and TEM confirmed the successful in situ growth and uniform distribution of FeSe₂ NPs onto the rGO nanosheet matrix. Furthermore, the FeSe₂/rGO nanohybrids showed superior and enhanced peroxidase-like activities compared to the bare FeSe₂, as demonstrated using two substrates, 3,3',5,5'-tetramethylbenzidine (TMB) and o-phenylenediamine (OPD). Michaelis-Menten kinetics showed a significantly lower K_m of 0.00952 mM for TMB and 7.62 mM for H₂O₂, along with a high V_max of 6.48 × 10^-8 M s^-1 (TMB) and 1.706 × 10^-6 Ms^-1 (H₂O₂) for FeSe₂/rGO, outperforming bare FeSe₂ and several other reported nanozymes. The kinetic parameters showed a strong substrate affinity and improved catalytic efficiency. Mechanistic study using terephthalic acid (fluorescent probe) revealed that ^•OH is majorly responsible for substrate oxidation, which is significantly enhanced by the synergistic effect of FeSe₂ and rGO. Furthermore, in support of our experimental results, molecular docking studies with multiple peroxidase proteins also showed significantly higher binding affinities for FeSe₂/rGO (-9.9 to -11.9 kcal mol^-1), as compared to FeSe₂ (-4.8 to -9.1 kcal mol^-1). Overall, this work highlights FeSe₂/rGO as a robust peroxidase mimic and efficient nanozyme with strong potential for colorimetric sensing and catalytic performance.