Blister evolution time invariance at very low electrolyte pH: H2SO4/graphite system investigated by electrochemical atomic force microscopy

When graphite is immersed in diluted sulfuric acid (H2SO4) electrolyte and positive potentials are applied to the sample, the surface undergoes an incipient oxidation process that develops gases (typically CO, CO2 and O2) both on the surface and in the underneath layers. These gases swell the surface and produce blisters, which damage and degrade the crystal. Some of these mechanisms are still under debate, such as the time interval Δt for blister evolution. Very recently, we studied the required Δt in 1 M H2SO4 electrolyte, finding a critical time for their formation of few seconds. Here, we give evidence that this time interval is almost unchanged if the electrolyte is further diluted until 1 mM, by combining electrochemical-atomic force microscopy, cyclic-voltammetry and normal pulse voltammetry.