Abstract Graphene and many 2D carbon allotropes are good support materials for single-atom catalysts (SACs) and have been successfully applied to many catalytic reactions. Herein, based on the egg tray graphene (ETG), a carbon allotrope constructed in our previous report, we designed ETG and three N-doped ETG supported Pd SACs, Pd@ETG-N _x (x= 0–3), for dehydrogenation of formic acid (HCOOH) by density functional theory. Our calculations show that ETG is easier for N doping than graphene, and Pd single atom can be stably adsorbed on the ETG with different N doping concentrations. Major pathways of formic acid dehydrogenation and dehydration were identified. We found that HCOOH dehydrogenation proceeds along the COOH-mediated pathway on each catalyst. With the increased N content in the substrate, the activity and H₂ selectivity of Pd SACs are greatly improved. Especially, among these four SACs, Pd@ETG-N₃ shows the best catalytic performance, which is even better than Pd(111). Furthermore, electronic analysis was made to reveal the metal-support interactions and the origin of the activity trend of Pd@ETG-N _x . Our study reveals the unique potential of carbon allotropes in catalyst design, and provides theoretical insights for rational design of efficient catalysts by adjusting the support and the coordination environment.