Computationally Guided Design of Single-Atom Catalysts Embedded on Reduced Graphitic Carbon Nitride Monolayers

The design of efficient single-atom catalysts (SAC) with optimal activity and selectivity for sustainable energy and environmental applications remains a challenge. Herein, first-principles calculations are performed to validate the feasibility of single TM atoms (3d, 4d, and 5d series) embedded in two different conformations of graphitic carbon nitride (g-C₃N₄) monolayers (planar and corrugated). We explore the effects of g-C₃N₄ monolayer nitrogen vacancies on the absorption of SAC considering three potential absorption scenarios, i.e. <i> on-vacancy</i>, <i>via-substitution</i>, and <i>on-center</i>, that correspond to different experimental conditions. Our results highlight the most stable configurations with the lowest formation energies and find that the absorption of single TM atoms<i> on-vacancy</i> and <i>on-center</i> sites are more favorable than <i>via-substitution</i>. Furthermore, in addition to thermodynamics stability, electrochemical stability is also investigated through the calculation of the dissolution potential of the SACs. Within the scenarios considered in this study, we find that Co, Fe, Rh, Ir, Pt, and Ni will produce the most robust SAC on reduced g-C₃N₄. Our findings provide guidance for the design and development of g-C₃N₄ sheets decorated with single TM atom catalysts for applications such as pollutant degradation, CO₂ reduction, N₂ fixation, selective oxidation, water splitting, and metal ion-based batteries.