Amorphous carbon thin film electrodes with intrinsic Pt-gradient for hydrogen peroxide detection

Nanoscale amorphous carbon thin films with intrinsic Pt gradient show great promise as new electrode materials for electrochemical detection of hydrogen peroxide. Embedding the Pt particles in the carbon matrix during the fabrication process allows tighter integration than, for example, adding them after the fabrication on top of the substrate. Especially, this approach can offer excellent electrochemical properties combined with CMOS compatibility, which is crucial for further device development. Here we provide extensive in depth electrochemical and physicochemical characterization of these novel materials by cyclic voltammetry (CV), chronoamperometry (CA), rotating disk electrode (RDE) experiments, transmission electron microscopy (TEM), Raman spectroscopy, x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Equipped with these detailed results on these materials we proceed to present some suggestions how the physicochemical properties correlate with the results from electrochemical measurements. (i) It is shown that coarsening of the initially very finely dispersed structure occurs both under electron bombardment during TEM imaging as well as during cyclic voltammetry in H2SO4. (ii) Further, it is shown that OH is adsorbed on small Pt islands much more strongly compared to the bulk Pt, which may heavily influence hydrogen peroxide redox reactions on these Pt-containing amorphous carbon films. (iii) Finally, we proceed to demonstrate that despite these complications, these materials show linear response for hydrogen peroxide reduction in neutral phosphate buffered saline combined with very fast response times.