Hydrogen peroxide production in the oxygen reduction reaction at different electrocatalysts as quantified by scanning electrochemical microscopy.

We present data for H2O2 production at eight different materials tested as electrocatalysts for the oxygen reduction reaction (ORR) in 0.5 M H2SO4 (Hg, Au, Ag, Cu, Pt, Pd, Pd80Co20, and Au60Cu40) using scanning electrochemical microscopy (SECM) as an alternative to the widely used rotating ring-disk electrode (RRDE) method. The amount of H2O2 is related to the total number of electrons, n, found in the O2 reduction reaction, with n = 2 showing only H2O2 production and n = 4 showing no H2O2 formation. From the SECM study Hg shows n close to 2, whereas Pt and Pd80Co20 show n-values near 4. The other materials show intermediate n-values as a function of potential.