Silica-nickel catalyst interfaces promote highly efficient CO₂ electroreduction to CO with a wide potential range

CO₂ electroreduction reaction (CO₂RR) offers a promising route to scale up CO₂-to-CO using renewable electricity and close the anthropogenic carbon cycle. To date, the undesirable hydrogen evolution reaction (HER) still occurs at the catalyst surface in CO₂RR, diminishing CO₂-to-CO production. In this work, we introduced silica on Ni to create active Ni-SiO_x interface sites and prepared silica-modified nickel nanoparticles on carbon nanotubes (Si-Ni-CNTs-800) as a highly effective electrocatalyst for CO₂-to-CO over a wide potential range. The catalyst achieved high CO Faradaic efficiency (FE_CO) of > 90 % in a wide potential range from −0.6 to −1.1 V vs RHE with a maximum FE_CO of 98 % at −0.9 V vs RHE with a CO partial current density of 21.5 mA cm⁻² by using standard H-type cell, and the catalyst could be used stably at least 12 h. With the support of X-ray absorption fine structure (EXAFS) and spectroscopic analysis, we demonstrated that the chemical bonds of Si-C and O-Si-C in the catalysts favor CO₂ activation to form the CO* intermediate and inhibition of HER, finally enhanced CO₂-to-CO conversion.