Two-dimensional metalloporphyrin-based covalent organic frameworks as bifunctional electrocatalysts for OER and ORR: A computational study

Metalloporphyrin-based covalent organic frameworks (COFs) with controllable metal sites and charge densities have become a front research field in catalysis. Herein, through the comprehensive density functional theory (DFT) computations, we explored the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) electrocatalytic activities on a series of two-dimensional (2D) metalloporphyrin-based graphdiyne analogs (TMPDY, TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, Pt), which are constructed by connecting metal coordinated 5,10,15,20-tetra-(4-phenyl)porphyrin rings and butadiyne. The computations show that Ir- and RhPDY can serve as outstanding bifunctional electrocatalysts for OER and ORR with ultralow overpotentials (0.45/ 0.37 and 0.34/0.47 V). The excellent catalytic behaviors are derived from the moderate adsorption interaction of oxygenated species as revealed by the scaling relationships and volcano curves. Remarkably, the adsorption free energies of intermediates are highly related to the electronic structures of TM-PDYs, characterized by the d-band center (epsilon d), the integrating crystal orbital Hamilton populations (ICOHP), and the universal descriptor phi. Our work not only reveals the OER and ORR catalytic performance of TM-PDYs but also provides an instructive strategy to design catalysts for the energy conversation and storage devices.