Electrocatalytic CO2 conversion on boron nitride nanotubes by metal single-atom engineering.

[Display omitted] • Electrocatalytic activity of metal doped boron nitride nanotubes for CO 2 reduction has been illustrated. • Rh@BNNT-B vac serves as promising ECO 2 RR catalysts with low limiting potential of −0.06 V for product HCOOH. • This work provides guidance for single-atom engineering on the exploration of the SAC catalysts. Atomically dispersed single metal on defective boron nitride nanotubes (BNNTs) show promising potential for CO 2 electrocatalytic reduction reaction (CO 2 ERR). Using density functional theory calculations, we explore the CO 2 ERR mechanism on single-atom catalysts (SACs) supported on BNNTs as well as assess their electrocatalytic performance of these catalysts. Boron or nitrogen vacancies in BNNTs are doped with palladium, platinum, or rhodium atoms to form three-coordinated metal centers, denoted as M@BNNT-V (M = Pt, Rh, Pd; V = B vacancy or N vacancy). Pt@BNNT with boron vacancies (Pt@BNNT-B vac) demonstrates a tendency to facilitate multi-electron reduction processes leading to the formation of complex molecules such as CH 2 O, CH 3 OH, and CH 4 with a limiting potential (U L) of −0.36 V. Conversely, Rh@BNNT-B vac and Pd@BNWNT-B vac show significantly lower limiting potentials of −0.06 V and −0.12 V, respectively, for the reduction to formic acid (HCOOH), with Rh@BNNT-B vac exhibiting enhanced activity and selectivity. Additionally, the deep reduction to other hydrocarbons or oxygenates, which typically requires potentials of −0.72 V and −0.60 V, appears less likely on both Rh and Pd doped BNNT-B vac , further delineating the nuanced performance differences induced by metal type and coordination environment within the BNNT structure. [ABSTRACT FROM AUTHOR]