Supercritical CO2-constructed intralayer [Bi2O2]2+ structural distortion for enhanced CO2 electroreduction

Abstract

Inducing crystal distortion in two-dimensional (2D) materials to increase the number of active sites is of great significance in improving the intrinsic activity of electrocatalysts for the CO₂ reduction reaction (CO₂RR). Developing 2D materials as thin as possible is required for this goal. Herein, taking layered BiOCl as a prototype model, we achieved the intralayer [Bi₂O₂]²⁺ structural distortion by using supercritical CO₂ as a solvent to reduce the number of interlayer chlorine atoms involved in the reaction. Contrary to expectations, further CO₂RR experiments indicate that thick nanoplates exhibit a high faradaic efficiency of ∼92% for conversion of CO₂ to formate in a wide potential window, whereas ultrathin nanosheets mainly produce H₂. Density functional theory calculation shows that increased [Bi₂O₂]²⁺ structural distortion in thick nanoplate layers is responsible for the finding. This strategy provides a new route to promoting the intrinsic activity of electrocatalysts, and provides us with a new insight into understanding thickness-dependent activity.