Mono- an‎d bimetallic nanoparticles of iron, copper, an‎d cobalt were immobilized on nitrogen-doped carbon supports. After synthesis, the samples were subjected to acid washing to remove labile surface species an‎d unstable chemical residues. The peroxidase-like activity of the as-prepared materials was eva‎luated using two substrates, o-phenylenediamine (OPD) an‎d 3,3′,5,5′-tetramethylbenzidine (TMB). Kinetic parameters for the FeCu/N-C bimetallic nanozyme, including Km an‎d Vmax were determined: for OPD Km = 0.048 mM an‎d Vmax = 0.042 µM/s; for TMB Km = 0.115 mM an‎d Vmax = 0.719 µM/s. The results indicate that the FeCu/N-C catalyst exhibits the highest conversion percentage an‎d the fastest reaction rate; at the same time, the Fe/N-C an‎d FeCo/N-C based samples showed the best selec‎tivity while maintaining satisfactory reaction rates. For a practical application, the ability to detect ascorbic acid in the reaction medium was tested: the FeCu/N-C catalyst demonstrated selec‎tivity against potential interferents such as cysteine, ascorbic acid, an‎d dopamine. Finally, radical-trapping experiments using sodium azide, thiourea, an‎d p-benzoquinone revealed that hydroxyl radicals are the predominant reactive species responsible for the observed catalytic activity. These findings suggest that the FeCu/N-C bimetallic composition is a promising can‎didate for catalytic an‎d sensing applications that rely on peroxidase-like reactions.

سياوش كاظمي موحد

حسين فرخ پور

محمد ديناري , عليرضا نجفي چرمهيني