Single-Atom Molybdenum-N 3 Sites for Selective Hydrogenation of CO 2 to CO.

The design of efficient non-noble metal catalysts for CO 2 hydrogenation to fuels and chemicals is desired yet remains a challenge. Herein, we report that single Mo atoms with a MoN 3 (pyrrolic) moiety enable remarkable CO 2 adsorption and hydrogenation to CO, as predicted by density functional theory studies and evidenced by a high and stable conversion of CO 2 reaching about 30.4 % with a CO selectivity of almost 100 % at 500 °C and very low H 2 partial pressure. Atomically dispersed MoN 3 is calculated to facilitate CO 2 activation and reduces CO 2 to CO* via the direct dissociation path. Furthermore, the highest transition state energy in CO formation is 0.82 eV, which is substantially lower than that of CH 4 formation (2.16 eV) and accounts for the dominant yield of CO. The enhanced catalytic performances of Mo/NC originate from facile CO desorption with the help of dispersed Mo on nitrogen-doped carbon (Mo/NC), and in the absence of Mo nanoparticles. The resulting catalyst preserves good stability without degradation of CO 2 conversion rate even after 68 hours of continuous reaction. This finding provides a promising route for the construction of highly active, selective, and robust single-atom non-precious metal catalysts for reverse water-gas shift reaction.