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