In Situ Halogen‐Ion Leaching Regulates Multiple Sites on Tandem Catalysts for Efficient CO2 Electroreduction to C2+ Products.

Tandem catalysts can divide the reaction into distinct steps by local multiple sites and thus are attractive to trigger CO2RR to C2+ products. However, the evolution of catalysts generally exists during CO2RR, thus a closer investigation of the reconstitution, interplay, and active origin of dual components in tandem catalysts is warranted. Here, taking AgI−CuO as a conceptual tandem catalyst, we uncovered the interaction of two phases during the electrochemical reconstruction. Multiple operando techniques unraveled that in situ iodine ions leaching from AgI restrained the entire reduction of CuO to acquire stable active Cu0/Cu+ species during the CO2RR. This way, the residual iodine species of the Ag matrix accelerated CO generation and iodine‐induced Cu0/Cu+ promotes C−C coupling. This self‐adaptive dual‐optimization endowed our catalysts with an excellent C2+ Faradaic efficiency of 68.9 %. Material operando changes in this work offer a new approach for manipulating active species towards enhancing C2+ products. [ABSTRACT FROM AUTHOR]