Exploring the oxygen electrode bi-functional activity of Ni–N–C-doped graphene systems with N, C co-ordination and OH ligand effects

Abstract

Development of efficient bifunctional electrocatalysts for reversible oxygen reduction (ORR) and oxygen evolution reactions (OER) are of prime importance in rechargeable metal-air batteries. In this work, a relatively unexplored and...

Boron Coordination Effect in Ni−Nx Doped Graphene Catalysts on the ORR Performance Based on DFT Calculations

“…Figure 3 plots the free energy diagrams of ORR pathways for all 23 structures at U=1.23 V, where the transformation of O 2 to OOH* is obviously the rate‐determining step for most structures except for NiN 2 B 2 . Figure 3(a) shows the free energy diagrams of Ni−N−C without B doping, in which the adsorption free energy of OOH* in NiN 4 catalyst is 4.85 eV, corresponding to the theoretical overpotential of 1.16 V, which is in good consistent with 1.17 V calculated by Liang et al., [20] and NiN 2 C 2 exhibits the lowest overpotential of 0.70 V.…”

“…[2,36] In order to explore the ORR catalytic mechanism of Ni-based SACs, we calculate the Gibbs free energy of the oxygen intermediate states adsorbed at Ni sites for selected 23 structures, and the calculated free energy of each reaction step and the overpotential η are summarized in Table S5. Figure 3 corresponding to the theoretical overpotential of 1.16 V, which is in good consistent with 1.17 V calculated by Liang et al, [20] and NiN 2 C 2 exhibits the lowest overpotential of 0.70 V.…”

“…[15][16][17] A variable strategy of improving the catalytic performance of single atom catalysts is to modulate the coordination environment of the metal active site for optimizing its electronic structure and adsorption free energy. [18,19] Zhao et al [20] explored the oxygen electrode bifunctional activity of NiÀ NÀ C doped graphene system with N, C coordina-tion and OH ligand effects, and found that N and C coordination environment around Ni atoms affects greatly the overall bifunctional activity of Ni based catalysts. Doping with atoms that have a smaller electronegativity compared to N atom can increase the electron density of Ni atom and strength the bond interaction between Ni and O atoms for activating the catalytic ORR reaction.…”

Theoretical Inspection of TM-P4C Single-Atom Electrocatalyst: Ultra-High Performance for bifunctional Oxygen Reduction and Evolution Reactions

“…And the catalytic mechanisms of other TM atoms embedded graphene with N coordination, such as Zn [33], Cu [34], Ni [35], have also been explored in recent years. In the experimental aspect, many TM-N-C catalysts (TM including Fe, Ni, Zn, Co, etc.)…”

Theoretical Inspection of TM-P4C Single-Atom Electrocatalyst: Ultra-High Performance for bifunctional Oxygen Reduction and Evolution Reactions

“…Lu et al [32] theoretically proposed the MnN4-gra system and suggested its ORR activity is prior than FeN4-gra. And the catalytic mechanisms of other TM atoms embedded graphene with N coordination, such as Zn [33], Cu [34], Ni [35], have also been explored in recent years. In the experimental aspect, many TM-N-C catalysts (TM including Fe, Ni, Zn, Co, etc.)…”