The influence of the Pt crystalline surface orientation on the glycerol electro-oxidation in acidic media

We investigated the electrochemical oxidation of glycerol on low-index Pt single crystals in acidic media (H2SO4 and HClO4) by cyclic voltammetry and Fourier Transform Infrared (FTIR) spectroscopy and we verified that this is a surface sensitive reaction. Pt(1 0 0) and Pt(1 1 0) surface structures favor the breaking of the CCC bond at low potentials (say 0.05 V), as seen by the formation of CO, one of the adsorbed residues of the glycerol dissociation, which poisons these surfaces even at high potentials. Pt(1 1 1) surface structure does not favor the CCC bond breaking at potentials as low as 0.05 V. However, Pt(1 1 1) is less poisoned by residues of glycerol dissociation and, for this reason, it is more active for glycerol oxidation than Pt(1 0 0) and Pt(1 1 0) at low potentials. Carbonyl containing compounds and CO2 were detected as reaction products of the glycerol oxidation on all investigated single-crystal Pt surfaces. The ratio between CO2 and carbonyl containing compounds is clearly much higher for Pt(1 0 0) and Pt(1 1 0) than for Pt(1 1 1).