Carbon nitride embedded with transition metals for selective electrocatalytic CO2 reduction

The development of efficient CO2 reduction catalysts is a challenge for artificial photosynthesis. We report here graphitic carbon nitride (g-C3N4) embedded with transition metals as a new class of CO2 reduction catalysts in aqueous environment. Bimetallic (NiMn or NiCu)-C3N4 catalysts are found to be more efficient than their mono-metal counterparts due to metal synergistic effects, delivering high Faradic efficiency for CO evolution of around 90 % over a wide potential range (−0.6 V to −0.9 V vs. reversible hydrogen electrode) with a low overpotential of 0.39 V. The high activity originates from the atomic modification of g-C3N4 matrix with metal atoms. And g-C3N4 not only serves as a coordination framework but also provides a favorable local environment for CO2 reduction. The present study contributes to our understanding of structure and activity trends of this kind of materials, and points to strategies for the rational design of more efficient CO2 reduction catalysts.