Sensing of H2O2 at low surface density assemblies of pt nanoparticles in polyelectrolyte

Amperometric detection of H2O2 was studied at random arrays of 2.5 nm polyacrylate-capped Pt nanoparticles (NP) assembled in poly(diallydimethylammonium chloride), PDDA, as a function of NP surface coverage. The arrays were assembled by varying the adsorption time of PDDA-modified electrodes in the nanoparticles solution. Pt NP-on-PDDA assemblies exhibited significant sensitivity and stability facing constant anodic polarization and a low limit of detection at small Pt mass in submonolayer coverage. The current output was measured at approximately 0.5 A M-1 cm(geom)(-2) over a linear range from 42 nM to 0.16 mM H2O2 at a loading of 0.87 mu g(Pt)/cm(2) or an estimated coverage of 0.4 of an assumed monolayer, or higher, and decreased with decreasing NP surface density to 0.2 A M-1 cm(geom)(-2) at a Pt loading of 190 ng/cm(2.)