SACs have the promise to combine the scalability of heterogeneous catalysts and the high atom economy of homogeneous catalysts , offering significant opportunities for atom-economical utilization of metals . Their unique electronic structure and unsaturated coordination environments have led to enhanced catalytic activity across numerous reactions . Among different classes of SACs, N-doped graphene SACs , featuring an isolated metal atom embedded in a graphitic material, more closely resemble their homogeneous counterparts compared to others. For instance, the Fe-N4 active site in Fe-SACs are viewed as analogous to hemes , where the Fe center is also coordinated to four nitrogen atoms, and molecular analogues have been developed to these SACs .