Design of catalyst for syngas conversion to C2 oxygenates via confining diatomic metal within the framework of 2D carbon-based materials

[Display omitted] •Coordination environment of diatomic RhCo could regulate catalytic performance of syngas-to-C2 oxygenates.•RhCo/g-C3N4, RhCo/GDY and RhCo/C2N catalysts perform excellent structural and thermal stability.•The screened RhCo/g-C3N4 catalyst is the most promising for syngas-to-C2 oxygenates.•g-C3N4 makes the diatomic RhCo lose more electron and d-band center far away from Fermi level.•A way is offered to design high-performance diatomic catalysts via altering their local coordination environment. The selectivity of syngas-to-C2 oxygenates still faces a big challenge. In the present study, the different 2D carbon-based substrates (g-C3N4, GDY and C2N) supported diatomic RhCo catalysts are constructed reasonably to enhance C2 oxygenates selectivity. The complicated reaction network is studied by means of DFT calculations; the influences of the species coverage, the reaction temperature and pressure are examined using microkinetic modeling. The results indicate that RhCo/g-C3N4, RhCo/GDY and RhCo/C2N catalysts have excellent structural stability. The preferred existence form of CHx(x = 1–3) monomer, as well as the activity and selectivity of CHx monomer and C2 oxygenates generation are strongly related to the coordination environment of 2D carbon-based material supported diatomic RhCo catalysts. The screened RhCo/g-C3N4 catalyst could perform the outstanding catalytic performance toward the generation of C2 oxygenates CH2CO and CH3CO, in which the coordination environment of g-C3N4 makes the diatomic RhCo cluster lose more electron and d-band center far away from Fermi level. This work provides an alternative way to construct 2D substrate supported diatomic metal catalysts in syngas-to-C2 oxygenates, adjusting 2D substrate type could change the local coordination environment of diatomic metal sites and further improve catalytic performance.