Active and conductive layer stacked superlattices for highly selective CO(2) electroreduction

Metal oxides are archetypal CO(2) reduction reaction electrocatalysts, yet inevitable self-reduction will enhance competitive hydrogen evolution and lower the CO(2) electroreduction selectivity. Herein, we propose a tangible superlattice model of alternating metal oxides and selenide sublayers in which electrons are rapidly exported through the conductive metal selenide layer to protect the active oxide layer from self-reduction. Taking BiCuSeO superlattices as a proof-of-concept, a comprehensive characterization reveals that the active [Bi(2)O(2)](2+) sublayers retain oxidation states rather than their self-reduced Bi metal during CO(2) electroreduction because of the rapid electron transfer through the conductive [Cu(2)Se(2)](2-) sublayer. Theoretical calculations uncover the high activity over [Bi(2)O(2)](2+) sublayers due to the overlaps between the Bi p orbitals and O p orbitals in the OCHO* intermediate, thus achieving over 90% formate selectivity in a wide potential range from −0.4 to −1.1 V. This work broadens the studying and improving of the CO(2) electroreduction properties of metal oxide systems.