Fabrication of a sensitive amperometric sensor for NADH and H₂O₂ using palladium nanoparticles-multiwalled carbon nanotube nanohybrid

Palladium nanoparticles decorated multiwalled carbon nanotubes (PdNPs-MWCNTs) were synthesized and simply cast on the surface of a glassy carbon electrode (GCE) to prepare an amperometric sensor. The fabricated sensor (PdNPs-MWCNTs/GCE) showed excellent electrocatalytic activity towards NADH and H₂O₂ oxidation and H₂O₂ reduction. A fast, linear and highly sensitive response was observed for NADH in the concentration range between 0.1 and 200 μM with a detection limit (S/N = 3) of 32 nM. Also, the sensor exhibited fast and sensitive responses (< 2 s) towards H₂O₂. The sensitivity and detection limit for H₂O₂ at the operating potential of + 0.35 V were 167 nA μM^{- 1} cm^{- 2} and 1.2 μM, respectively and better than those obtained at the operating potential of - 0.25 V (68 nA μM^{- 1} cm^{- 2} and 14 μM). Moreover, further modification of the proposed sensor by glucose oxidase led to the fabrication of a glucose biosensor with satisfactory performance.