Cobalt Single Atom Catalysts Supported on Different MXenes for the Alkaline Oxygen Evolution Reaction: First-Principles Approach

초록

The development of commercially available water-splitting system is essential to combining green hydrogen production with renewable energy. In this respect, the replacement of noble-metal electrocatalysts to lower the high cost of materials is needed. In this study, we introduce the Co single atom catalysts (SACs) supported on different transition metal-based MXenes (M2CO2, M = Cr, Hf, Mo, Nb, Ta, Ti, V, W, and Zr) for the efficient oxygen evolution reaction (OER) under alkaline condition. Using density functional theory (DFT) calculation, we investigated Co/M2CO2 electrochemical activity and stability. As a result, the Co/V2CO2 catalyst was predicted to possess the best OER activity (Uonset = 0.96 V), and most of Co/M2CO2 catalysts showed significant electrochemical stability with highly positive dissolution potentials except for Co/Zr2CO2, Co/Nb2CO2 Co/Hf2CO2 and Co/Ta2CO2. In addition, we unveiled that charge loss in Co single atom weakens the oxygen adsorption energies, which can improve the OER activity, via Bader charge analysis. In addition, through the density of states analysis near the Fermi energy level, we found that higher DOS(density of states) values near the Fermi energy level correlate with enhanced catalytic activity. Based on the density of states analysis, d-band states of Co single atom were identified to be tunable with various MXene supports utilization. We believe that this study will provide significant insights for the future development of next-generation OER catalysts.

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