Lattice strain and interfacial engineering of a Bi-based electrocatalyst for highly selective CO₂ electroreduction to formate

Surface strain tuning in a coupled heterostructure efficiently engineers the catalytic performance of heterogeneous catalysts by altering the electronic structures and boosting electron transport. Generally, Bi-based catalysts are more favorable than ZnO for CO₂ electroreduction to formate, but Bi is much more costly than Zn. Herein, a new Bi₂O₂CO₃/ZnO heterojunction catalyst with porous nanoplate morphology is synthesized through a hexadecyl trimethyl ammonium bromide-templated hydrothermal reaction for a highly efficient catalytic CO₂ reduction reaction (CO₂RR) to produce formate. The Bi₂O₂CO₃/ZnO catalyst shows a maximum Faradaic efficiency of 92% for formate production at -1.0 V vs. reversible hydrogen electrode (RHE) and a large partial current density of -200 mA mg_Bi^-1 at -1.2 V vs. RHE. More importantly, the mass activity of Bi₂O₂CO₃/ZnO normalized by Bi mass is an approximately 3.1-fold enhancement over that of the pristine Bi₂O₂CO₃ at -1.2 V vs. RHE. By coupling X-ray photoelectron spectroscopy and adsorption spectroscopy measurements, the charge transfer from the Zn atom to the Bi atom through a heterogeneous interface results in an electron-enriched Bi₂O₂CO₃ surface, which facilitates CO₂ capture and activation. Meanwhile, compressive stress produced on the catalyst surface helps optimize the adsorption energy of the reaction intermediate, synergistically enhancing the catalytic selectivity and activity of Bi₂O₂CO₃/ZnO for electrochemical CO₂ reduction to formate.