Modification of the Coordination Environment of Active Sites on MoC for High-Efficiency CH₄ Production

Modulating the coordination environment of active sites on catalyst surfaces is crucial to developing effective catalysts and controlling catalysis. However, this may be a highly challenging procedure. Guided by the first-principles calculations, the modification of the coordination environment of active sites on MoC nanoparticle surfaces is experimentally accomplished by anchoring pyridinic N atom rings of holey graphene on Mo atoms. The rings produce electrostatic forces that enable the tuning of the Mo sites′ affinity to reaction intermediates, which passivates Mo hollow sites, activates Mo top sites, and reduces the overadsorption of OH on the Mo active sites, as predicted by calculations. The atomic-level modification is well confirmed by atomic-resolution imaging, high-resolution electron tomography, synchrotron soft X-ray spectroscopy, and operando electrochemical infrared spectroscopy. Consequently, the Faradaic efficiency for CO₂ reduction to CH₄ is enhanced from 16% to 89%, a record high efficiency so far, in aqueous electrolytes. It also exhibits a negligible activity loss over 50 h.