Beyond CO2 activation: shedding light on N2O electroreduction catalyzed by low valent iron porphyrin
Résumé
In addition to its euphoric and anesthetic properties, nitrous oxide (N 2 O) is known for its significant impact on the environment. The increase of atmospheric N 2 O since the start of the industrial era has contributed to greenhouse gas emission, with a greater global warming potential than carbon dioxide (CO 2 ), as well as ozone layer depletion.[1] Therefore, N 2 O activation is of key interest to help mitigate environmental issues. However, its high chemical inertness makes it challenging.[2] For this purpose, the electrochemical reduction of N 2 O into dinitrogen (N 2 ) using molecular catalysts is a promising approach.[3] Taking inspiration from CO 2 electroreduction catalysis, widely studied with iron porphyrin molecular catalysts, our recent work has revealed the interesting catalytic activity of low-valent iron tetraphenylporphyrin (FeTPP) electrochemically generated for the selective reduction of N 2 O into N 2 [4]. Here we illustrate the investigation of the mechanism involved in the N-O bond activation (deoxygenation reaction) and we compare it with the C-O bond activation (in CO 2 ), using electrochemical and spectro-electrochemical tools. Particular attention has been paid to determine the active form of the catalyst as well as the role of the acidic co-substrate.