Prompting CO2 Electroreduction to Ethanol by Iron Group Metal Ion Dopants Induced Multi-sites at the Interface of SnSe/SnSe2 p–n Heterojunction

Abstract

The development of non-copper-based materials for CO₂ electroreduction to ethanol with high selectivity at large current density is highly desirable, but still a great challenge. Herein, we report iron group metal ions of M²⁺ (M=Fe, Co, or Ni)-doped amorphous/crystalline SnSe/SnSe₂ nanorod/nanosheet hierarchical structures (a/c-SnSe/SnSe₂) for selective CO₂ electroreduction to ethanol. Iron group metal ions doping induces multiple active sites at the interface of M²⁺-doped SnSe/SnSe₂ p-n heterojunction, which strengthens *CO intermediate binding for further C−C coupling to eventual ethanol generation. As a representative, Fe_9.0%-a/c-SnSe/SnSe₂ exhibits an ethanol Faradaic efficiency of 62.7 % and a partial current density of 239.0 mA cm⁻² at −0.6 V in a flow cell. Moreover, it can output an ethanol Faradaic efficiency of 63.5 % and a partial current density of 201.2 mA cm⁻² with a full-cell energy efficiency of 24.1 % at 3.0 V in a membrane electrode assembly (MEA) electrolyzer. This work provides insight into non-Cu based catalyst design for stabilizing the key intermediates for selective ethanol production from CO₂ electroreduction.