The influence of stepped Pt[n(111)×(110)] electrodes towards glycerol electrooxidation: Electrochemical and FTIR studies

In situ Fourier Transform Infrared (FTIR) spectroscopy and cyclic voltammetry were combined for the first time to study the influence of Pt steps sites, belonging to the series of Pt(S)[n(111)x(111)], over the glycerol electrooxidation reaction (GEOR) in acid media. The spectroelectrochemical studies exhibited that the adsorption and electrooxidation process of glycerol at Pt surfaces are quite sensitive to the monoatomic ‘defect’ added on the well-ordered surface. The presence of (110) steps on the (111) terraces plays a significant role in the CV profiles with the presence of two peaks well-defined on the positive-going scan at 0.57 and 0.70 V, which the first one can be related to the (111) oriented terraces, and the second one to the (110) oriented ‘defects’. The in situ FTIR detached the presence of three well-discernible bands (ν(CO), ν(COL) and ν(CO2)) which give us new insights about glycerol electrooxidation mechanism and its dependence with the surface structure. The Pt(111) has shown the higher electroactivity towards GEOR, while Pt(110) has demonstrated greater ability in breaking C–C bond to convert into CO2. Moreover, for the Pt(111) and Pt(554) electrodes, the C–C seems to break only during the positive scan. On the other hand, at the beginning of the reverse scan, the incomplete oxidation prevails for Pt(111) and Pt(554) and, thus, being more selective to form only C3 products as dihydroxyacetone, glycolic acid and glyceric acid.