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The True Fate of Pyridinium in the Reportedly Pyridinium‐Catalyzed Carbon Dioxide Electroreduction on Platinum
Author(s) -
Olu PierreYves,
Li Qi,
Krischer Katharina
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201808122
Subject(s) - chemistry , pyridinium , catalysis , formate , platinum , pyridine , electrolysis , inorganic chemistry , protonation , methanol , electrolyte , electrocatalyst , photochemistry , medicinal chemistry , electrochemistry , electrode , organic chemistry , ion
Protonated pyridine (PyH + ) has been reported to act as a peculiar and promising catalyst for the direct electroreduction of CO 2 to methanol and/or formate. Because of recent strong incentives to turn CO 2 into valuable products, this claim triggered great interest, prompting many experiments and DFT simulations. However, when performing the electrolysis in near‐neutral pH electrolyte, the local pH around the platinum electrode can easily increase, leading to Py and HCO 3 − being the predominant species next to the Pt electrode instead of PyH + and CO 2 . Using a carefully designed electrolysis setup which overcomes the local pH shift issue, we demonstrate that protonated pyridine undergoes a complete hydrogenation into piperidine upon mild reductive conditions (near 0 V vs. RHE). The reduction of the PyH + ring occurs with and without the presence of CO 2 in the electrolyte, and no sign of CO 2 electroreduction products was observed, strongly questioning that PyH + acts as a catalyst for CO 2 electroreduction.