Abstract
Phosphoric acid is an inorganic acid used for producing graphene sheets by delaminating graphite in (electro-)chemical baths. The observed phenomenology during the electrochemical treatment in phosphoric acid solution is partially different from other acidic solutions, such as sulfuric and perchloric acid solutions, where the graphite surface mainly forms blisters. In fact, the graphite surface is covered by a thin layer of modified (oxidized) material that can be observed when an electrochemical potential is swept in the anodic current regime. We characterize this particular surface evolution by means of a combined electrochemical, atomic force microscopy and Raman spectroscopy investigation.
Highlights
Sulfuric (H2SO4), perchloric (HClO4) and phosphoric (H3PO4) acid in aqueous solutions have been used traditionally for the intercalation of anions in graphite in order to produce graphene [1]
When the EC potential is swept towards more positive values, the anodic current increases and a clear feature in the cyclic voltammetry (CV) curve is observed at about +1.48 V (Figure 1a), indicating that a charge transfer process is activated at the graphite electrode
See panel c, the anodic feature is placed at about 1.40 V, while the cathodic peak is at −0.75 V suggesting that the processes require a lower activation energy
Summary
Sulfuric (H2SO4), perchloric (HClO4) and phosphoric (H3PO4) acid in aqueous solutions have been used traditionally for the intercalation of anions in graphite in order to produce graphene [1]. When the EC potential is swept towards more positive values, the anodic current increases and a clear feature in the cyclic voltammetry (CV) curve is observed at about +1.48 V (Figure 1a), indicating that a charge transfer process is activated at the graphite electrode.
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