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