A new mechanism for the selectivity to C-1 and C-2 species in the electrochemical reduction of carbon dioxide on copper electrodes

作者：Schouten K J P; Kwon Y; van der Ham C J M; Qin Z; Koper M T M^*

来源：Chemical Science, 2011, 2(10): 1902-1909.

DOI：10.1039/c1sc00277e

We have investigated the reaction mechanism of the electrochemical reduction of carbon dioxide to hydrocarbons on copper electrodes. This reaction occurs via two pathways: a C-1 pathway leading to methane, and a C-2 pathway leading to ethylene. To identify possible intermediates in the reduction of carbon dioxide we have studied the reduction of small C-1 and C-2 organic molecules containing oxygen. We followed the formation and consumption of intermediates during the reaction as a function of potential, using online mass spectrometry. For the C-1 pathway we show that it is very likely that CHOads is the key intermediate towards the breaking of the C-O bond and, therefore, the formation of methane. For the C-2 pathway we suggest that the first step is the formation of a CO dimer, followed by the formation of a surface-bonded enediol or enediolate, or the formation of an oxametallacycle. Both the enediol(ate) and the oxametallacycle would explain the selectivity of the C-2 pathway towards ethylene. This new mechanism is significantly different from existing mechanisms but it is the most consistent with the available experimental data.

• 出版日期2011