Novel Two-Dimensional Metal Organic Frameworks: High-Performance Bifunctional Electrocatalysts for OER/ORR

For the development of energy storage and conversion, it is essential to explore high performance bifunctional catalysts with oxygen reduction and evolution reaction (ORR and OER). Two-dimensional (2D) metal-organic frameworks (MOFs) with abundant exposed active sites have great potential as catalyst materials with high electrocatalytic activity. Herein, a sequence of 2D MOF (TMN2O2, TM = Cr, Mn, Fe, Co, Ni, Cu, Zn) structures with 2,3,6,7,10,11-hexahydroxytriphenylene and 2,3,6,7,10,11triphenylenehexamine were designed and investigated for their catalytic performance in ORR and OER by using density functional theory. Calculation results reveal that TMN2O2 (TM = Cr, Mn, Fe, Co, Ni) structures have superior thermodynamic and electrochemical stability during the electrocatalytic process. Based on oxygen and water molecule activation and free energy calculations, the CoN2O2 structure exhibits superior electrocatalytic performance for ORR and OER with low overpotential values of 0.33 and 0.30 V, respectively. The high bifunctional electrocatalytic activity for OER/ORR can be attributed to the moderate adsorption interaction of CoN2O2 structure with key intermediates. The valence orbital contribution of Co-3dz2 is critical for adjusting the interaction with the *OOH intermediate, resulting in enhancing the electrocatalytic performance for both ORR and OER.