Electrooxidation of glycerol studied by combined in situ IR spectroscopy and online mass spectrometry under continuous flow conditions

Using a combined spectro-electrochemical DEMS/ATR-FTIRS set-up, we have investigated the adsorption/oxidation of glycerol on a Pt thin film electrode by potentiodynamic, potentiostatic, and adsorbate-stripping experiments. The potential and time dependent development of the glycerol adlayer was followed by highly surface sensitive in situ ATR-FTIR spectroscopy, while the volatile products formed during the glycerol adsorption/oxidation process were simultaneously monitored by online differential electrochemical mass spectrometry (DEMS). For the assignment of the detected glycerol adsorbates, comparative experiments were carried out, investigating the adsorption/oxidation of glyceraldehyde and glyceric acid. The data show that (i) during the adsorption/oxidation of glycerol, COad is formed in the potential range between 0.1 and 0.7 VRHE, which can be oxidized further to CO2 at potentials above 0.5 V, that (ii) beside COad, adsorbed glycerol (at 0.3 and 0.4 V) and glycerate (between 0.6 and 0.9 V) are formed, that (iii) glyceric acid is a dead end in the electrochemical oxidation of glycerol, and that (iv) glyceraldehyde is an intermediate to COad formation.