Dynamically Formed Surfactant Assembly at the Electrified Electrode- Electrolyte Interface Boosting CO2 Electroreduction

WX Ge and YX Chen and Y Fan and YH Zhu and HL Liu and L Song and Z Liu and C Lian and HL Jiang and CZ Li, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 144, 6613-6622 (2022).

DOI: 10.1021/jacs.2c02486

Electrocatalytic reactions occur in the nanoscalespace at the electrified electrode-electrolyte interface. It is wellknown that the electrode-electrolyte interface, also called asinterfacial microenvironment, is difficult to investigate due to theinterference of bulk electrolytes and its dynamic evolution inresponse to applied bias potential. Here, we employ electro-chemical co-reduction of CO2and H2O on commercial Agelectrodes as a model system, in conjunction with quaternaryammonium cationic surfactants as electrolyte additives. We probebias-potential-driven dynamic response of the interfacial micro- environment as well as the mechanistic origin of catalyticselectivity. By virtue of comprehensive in situ vibrationalspectroscopy, electrochemical impedance spectroscopy, andmolecular dynamics simulations, it is revealed that the structure of surfactants is dynamically changed from a random distributionto a nearly ordered assembly with increasing bias potential. The nearly ordered surfactant assembly regulates the interfacial waterenvironment by repelling isolated water and suppressing water orientation into an ordered structure as well as promotes CO2enrichment at the electrified interface. Eventually, the formed hydrophobic-aerophilic interface microenvironment reduces theactivity of water dissociation and increases the selectivity of CO2electroreduction to CO. These results highlight the importance ofregulating the interfacial microenvironment by organic additives as a means of boosting the electrochemical performance inelectrosynthesis and beyond

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