Surface structure effects of electrocatalytic conversion of ethane on Pt single crystal electrodes

Abstract

Electrocatalytic conversion of short-chain hydrocarbons is a promising alternative route of traditional heterogeneous catalytic conversion, due to the advantages of ease in selectivity tuning by electrode potential, effective utilization of renewable electricity and reducing CO2 emission. In this study, we investigated electrochemical conversion of ethane on Pt single crystal electrodes (Pt(S)[n(1 0 0) × (1 1 0)] and Pt(S)[n(1 0 0) × (1 1 1)] step surfaces) for the first time through the combination of cyclic voltammetry (CV) and in situ FTIR spectroscopy (In situ FTIRS). The results revealed that the reactivity of ethane conversion is highly sensitive to the surface structure of Pt, and the highest reactivity is achieved on Pt(1 0 0) surface. The introduction of step sites on (1 0 0) terrace will dramatically decrease the activity. Cyclic voltammogram of ethane oxidation on Pt(1 0 0) shows three oxidative peaks in positive-going potential scan and one oxidative peak in negative-going potential scan. In the potential range from 0.25 to 0.55 V, ethane can be dissociated to form mainly bridge-bonded CO, which can be further oxidized to CO2 at high potentials. The other promising pathway is without CC breaking, resulting in valuable products such as acetic acid and acetaldehyde at a relatively low potential of 0.50 V. At a potential over 0.60 V, bridge-bonded acetate was detected by in situ FTIR spectroscopy. Based on the experiment results, a possible reaction mechanism for the electrocatalytic conversion of ethane on Pt(1 0 0) was proposed.