Single B-vacancy enriched α 1 -borophene sheet: an efficient metal-free electrocatalyst for CO 2 reduction.

By employing first principles calculations, we have studied the electronic structures of pristine (α 1 ) and different defective (α 1- t 1 , α 1- t 2 ) borophene sheets to understand the efficacy of such systems as metal-free electrocatalysts for the CO 2 reduction reaction. Among the three studied systems, only α 1- t 1 , the defective borophene sheet created by removal of a 5-coordinated boron atom, can chemisorb and activate a CO 2 molecule for its subsequent reduction processes, leading to different C 1 chemicals, followed by selective conversion into C 2 products by multiple proton coupled electron transfer steps. The computed onset potentials for the C 1 chemicals such as CH 3 OH and CH 4 are low enough. On the other hand, in the case of the C 2 reduction process, the C-C coupling barrier is only 0.80 eV in the solvent phase which produces CH 3 CHO and CH 3 CH 2 OH with very low onset potential values of -0.21 and -0.24 V, respectively, suppressing the competing hydrogen evolution reaction.