Electrocatalytic CO2 reduction to ethylene over CuOx boosting CO2 adsorption by lanthanide neodymium†

Abstract

CO₂ electrocatalytic reduction (CO₂ER) is an excellent way for synthesizing value-added products and achieving carbon neutrality. While C₂₊ products, such as C₂H₄, C₂H₅OH, etc., have higher energy densities and are more valuable than C₁ products, their synthesis is more challenging. In the present work, a series of easily prepared lanthanide neodymium-doped CuOx catalysts (denoted as CuaNdOx, a = 0.2, 0.5, 1, 2, and 5) were developed and applied in CO₂ER to produce C₂H₄. In an H-type cell, the Cu₂NdOx catalyst with a Co/Nd molar ratio of 2/1 demonstrated the best catalytic performance with a high FE_C2H4 of 54.4% and a current density of 28.4 mA cm⁻² at −1.19 V (vs. RHE) in 0.5 M KCl electrolyte. Characterization results showed that the introduction of neodymium could effectively stabilize the Cu(i) species and enhance CO₂ adsorption on the catalyst. In situ Raman spectra and DFT calculation confirmed that the Nd sites favor the adsorption and activation of CO₂, while the Cu sites are responsible for reducing CO₂ to *COOH and *CO. The formed *CO was then coupled to ethylene, further improving the Faradaic efficiency of ethylene (FE_C2H4). It is noteworthy that this is the first instance of using lanthanide neodymium as a promoter in Cu-based material catalyzed CO₂ER. The present work not only provides efficient Cu–Nd bimetallic catalysts for CO₂ER to ethylene but also opens up a new avenue of utilizing Nd-based lanthanide metals in catalysis.