| Affiliation: | 1. Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore, 117574 Singapore
Institute of Materials Research and Engineering, Agency for Science Technology and Research (A* STAR), Singapore, 138634 Singapore;2. Department of Physics, National University of Singapore, Singapore, 117551 Singapore;3. Department of Chemistry and Shenzhen Grubbs Institute, Southern University of Science and Technology (SUSTech), Shenzhen, 518055 China;4. Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore, 117574 Singapore;5. Institute of Materials Research and Engineering, Agency for Science Technology and Research (A* STAR), Singapore, 138634 Singapore;6. Department of Mechanical Engineering, National University of Singapore, Singapore, 117575 Singapore |
| Abstract: | Previous research of molybdenum-based electrocatalysts for nitrogen reduction reaction (NRR) has been largely considered on either isolated Mo single atoms (MoSAs) or Mo carbide particles (e.g., Mo2C) separately, while an integrated synergy (MoSAs-Mo2C) of the two has never been considered. The theoretical calculations show that the Mo single atoms and Mo2C nanoparticles exhibit, respectively, different catalytic hydrogen evolution reaction and NRR selectivity. Therefore, a new role-playing synergistic mechanism can be well enabled for the multistep NRR, when the two are combined on the same N-doped carbon nanotubes (NCNTs). This hypothesis is confirmed experimentally, where the MoSAs-Mo2C assembled on NCNTs (MoSAs-Mo2C/NCNTs) yields an ammonia formation rate of 16.1 µg h?1 cmcat?2 at ?0.25 V versus reversible hydrogen electrode, which is about four times that by the Mo2C alone (Mo2C/NCNTs) and 4.5 times that by the MoSAs alone (MoSAs/NCNTs). Moreover, the Faradic efficiency of the MoSAs-Mo2C/NCNTs is raised up to twofold and sevenfold of the Mo2C/NCNTs and MoSAs/NCNTs, respectively. The MoSAs-Mo2C/NCNTs also demonstrate outstanding stability by the almost unchanged catalytic performance over 10 h of the chronoamperometric test. The present study provides a promising new prototype of synchronizing the selectivity and activity for the multistep catalytic reactions. |
