Theoretical evidence on pyridinic nitrogen in N, S-coordinated Co single atom catalyst as dominant active site promoting H2 cleavage, H diffusion, and hydrogenation activity.

[Display omitted] • Low H 2 dissociation barrier is obtained using N, S-doped Co single atom catalyst (Co-N 3 SN-def1); • Frustrated Lewis pair comprised of Co and pyridinic N sites facilitate the H 2 dissociation; • H transfer via the solvent water is the main diffusion pathway; • Moderate H adsorption strength at pyridinic N site contributes to the low breaking barrier of N-O bond in nitrobenzene. The limitation of isolated metal active sites in single atom catalysts (SAC) hinder their application in hydrogenation reactions, necessitating the creation of additional active site beyond the metal site. This study introduces pyridinic N and S atoms into the N/C sheet, optimally adjusting the local environment of the Co site. This adjustment synergistically enhances H 2 activation, H diffusion, and promotes the hydrogenation of nitrobenzene into aniline. The sterically hindered Co acidic site and N basic site, known as frustrated Lewis pairs, in defect-containing Co-N 3 SN-def1 model cooperatively facilitate the highly efficient cleavage of the H 2 molecule with a barrier of only 0.37 eV. The findings suggest that the pyridinic N site in the Co-N 3 SN-def1 model acts as a reservoir for *H, significantly contributing to the enhanced activity for the hydrogenation of nitrobenzene. The mechanism unveiled in this study offers valuable insights for designing efficient heterogeneous catalysts for target hydrogenation reactions. [ABSTRACT FROM AUTHOR]