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Metal-Free Boron Nitride Nanoribbon Catalysts for Electrochemical CO₂ Reduction: Combining High Activity and Selectivity

Tang, Shaobin, Zhou, Xunhui, Zhang, Shiyong, Li, Xiaokang, Yang, Tongtong, Hu, Wei, Jiang, Jun, Luo, Yi
ACS applied materials & interfaces 2018 v.11 no.1 pp. 906-915
active sites, boron nitride, carbon dioxide, carbon monoxide, catalysts, catalytic activity, density functional theory, electrochemistry, electrodes, energy costs, ethanol, ethylene, hydrogen, hydrogen production, hydrogenation, materials science, methane
Developing metal-free catalysts for reduction of CO₂ into energy-rich products is a popular yet very challenging topic. Using density functional theory calculations, we investigated the electrocatalytic performance of C-doped and line-defect (Ld)-embedded boron nitride nanoribbons (BNNRs) for CO₂ reduction reaction (CRR). Because of the presence of bare edge B atoms neighboring to C dopant and C₂ dimer as active sites, defective BNNRs exhibit high CRR catalytic activity and selectivity. The Ld-embedded BNNR structures with C₂ dimer can not only convert CO₂ into CO with very low overpotential of −0.5 V versus reversible hydrogen electrode but also ensure high selectivity in deactivating the hydrogenation channel of the desorbed CO to CH₄. The C-doped zigzag and armchair BNNRs bind strongly to the CO intermediate and thus promote the selective conversion of CO₂ to CH₄, with the lower energy cost on the armchair ribbon than the zigzag one. The presence of edge B atoms and C dopant as dual active sites in BNNRs enables effective couplings between *CH₂ and CO intermediates, leading to the formation of C₂ products including C₂H₄ and C₂H₅OH, with a high selectivity for C₂H₅OH. Importantly, unwanted hydrogen evolution reaction is suppressed during CRR catalyzed by these BNNR-based configurations. Overall, the present findings highlight a promising new class of low-cost, metal-free electrocatalysts combining high CRR activity and selectivity.