CO2 electrolysis is a key step in CO2 conversion into fuels and chemicals as a way of mitigating climate change. We report the synthesis and testing of a series of new anion‐conductive membranes (tradenamed Sustainion™) for use in CO2 electrolysis. These membranes incorporate the functional character of imidazolium‐based ionic liquids as co‐catalysts in CO2 reduction into a solid membrane with a styrene backbone. We find that the addition of an imidazolium group onto the styrene side‐chains increases the selectivity of the reaction from approximately 25 % to approximately 95 %. The current at 3 V is increased by a factor of 14. So far we have been able to tune these parameters to achieve stable cells that provide current densities higher than 100 mA cm−2 at 3 V cell potential with a CO product selectivity over 98 %. Stable performance was observed for 6 months of continuous operation (>150 000 000 turnovers). These results demonstrate that imidazolium polymers are ideal membranes for CO2 electrolysis.

Carbon dioxide (CO 2 ) electrolysis provides a pathway to close the anthropogenic carbon cycle and store renewable energy, but the stability, selectivity, efficiency and rate of such process needs to be improved. In this paper, we explore the use of Sustainion imidazolium-functionalized membranes and ionomers to improve the performance of that process. Potentiometric runs at a fixed current of 200 mA/cm 2 using Sustainion membranes and ionomers showed that one can maintain 98% selectivity at about 3V applied potential for five months, with a voltage increase of only 3 μV/hour. Other runs showed stable performance at 400 and 600 mA/cm 2 . These results pave the way for commercialization of CO 2 electrolysis, providing a viable pathway to recycle CO 2 back to fuels.

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The ethanol electrooxidation reaction (EOR) on polycrystalline Pt catalysts in alkaline solution was studied for the first time with broadband sum-frequency generation (BB-SFG) spectroscopy. We find that CÀC bond cleavage and CO formation occur as early as 0.05 V versus reversible hydrogen electrode (RHE), and that CO is oxidized at ∼0.45 V, which is 0.2 V lower than in acidic media. In order to track the oxidation of singlecarbon intermediates, we have monitored the oxidation of isotopically labeled ethanol ( 12 CH 3 13 CH 2 OH). Surface-adsorbed 12 CO and 13 CO are observed and show very different potential-dependent behaviors. 13 CO molecules formed from preoxidized carbon species such as ÀCH x O, show the behavior expected from studies of CO-saturated alkaline media. 12 CO, however, which is indicative of the oxidation of methyl-like species (ÀCH x ) on the catalyst surface, is observed at unusually high potentials. The strongly adsorbed ÀCH x is not oxidatively removed from the surface until the electrode potential is swept past 0.65 V.

A B S T R A C TThe electrochemical production of syngas would enable production of chemicals and transportation fuels from carbon dioxide, water and renewable energy, but a suitable process at the moment does not exist. In this paper we consider two options for syngas production: (i) CO 2 electrolysis to produce CO, water electrolysis to produce H 2 and then mixing the CO and H 2 to yield syngas; and (ii) the simultaneous coelectrolysis of CO 2 and H 2 O in a single electrolyzer. The results show that both processes can produce syngas at industrially important rates. In this paper we demonstrate CO 2 electrolysis at 100 mA/cm 2 , i.e., about 20 turnovers/s, and water electrolysis at 8 A/cm 2 at 2.0 V/cell, with about 1,600 turnovers/s. Both systems are stable for a thousand hours or more, i.e., millions of turnovers. We also demonstrate simultaneous CO and H 2 production in a single electrolyzer. These results demonstrate that syngas can be produced at industrially important rates via electrolysis.