Single B-vacancy enriched α1-borophene sheet: an efficient metal-free electrocatalyst for CO2 reduction

Abstract

By employing first principles calculations, we have studied the electronic structures of pristine (α₁) and different defective (α_1−t1, α_1−t2) borophene sheets to understand the efficacy of such systems as metal-free electrocatalysts for the CO₂ reduction reaction. Among the three studied systems, only α_1−t1, the defective borophene sheet created by removal of a 5-coordinated boron atom, can chemisorb and activate a CO₂ molecule for its subsequent reduction processes, leading to different C₁ chemicals, followed by selective conversion into C₂ products by multiple proton coupled electron transfer steps. The computed onset potentials for the C₁ chemicals such as CH₃OH and CH₄ are low enough. On the other hand, in the case of the C₂ reduction process, the C–C coupling barrier is only 0.80 eV in the solvent phase which produces CH₃CHO and CH₃CH₂OH with very low onset potential values of −0.21 and −0.24 V, respectively, suppressing the competing hydrogen evolution reaction.