TY - JOUR
T1 - First principle studies of oxygen reduction reaction on N doped graphene: Impact of N concentration, position and co-adsorbate effect
AU - Man, Isabela-Costinela
AU - Tranca, Ionut C.
AU - Soriga, Stefan-Gabriel
PY - 2020/4/30
Y1 - 2020/4/30
N2 - Density Functional Theory calculations were performed on N doped graphene sheet to investigate the trends for adsorption energy variation of oxygen reduction reaction intermediates (HOO*, O*, HO*) when the N concentration increases from 0N (0%) to 1N (33%), to 2N (67%) and to 3N (100%) around the C active site. The impact of the distance between the doping N atoms and the C active site is also studied. Last, the impact of additionally co-adsorbed HO*/O* intermediates was probed. For all the studied systems the magnitudes with which varies the adsorption energies are shaped by the HO*/HOO* capability of accommodating less charge than O* (i.e according to octet rule 1e− vs. 2e−). When N concentration increases, adsorption energy of O* increases with a much higher magnitude than that of HO*/HOO* (i.e with 5 eV vs. 2.7 eV, when going from 0N to 3N). In the presence of the O* co-adsorbate, adsorption energy of intermediates on the investigated active site decrease with a much higher magnitude than when 1HO* is present as co-adsorbate (≈2 eV vs. 1 eV). The theoretical overpotential trends are evaluated using ΔGHO*-ΔGO* descriptor and are found to be significantly influenced by all these environmental changes around the active site. By applying the water stabilization effects, the activity trends remain the same as when it is not taken into account. These results reveal aspects of ORR activity variations that take place when N is clustering on graphene sheets, structures that can be possible as a function of synthesis procedures that could lead to unevenly distribution of dopants in the matrix.
AB - Density Functional Theory calculations were performed on N doped graphene sheet to investigate the trends for adsorption energy variation of oxygen reduction reaction intermediates (HOO*, O*, HO*) when the N concentration increases from 0N (0%) to 1N (33%), to 2N (67%) and to 3N (100%) around the C active site. The impact of the distance between the doping N atoms and the C active site is also studied. Last, the impact of additionally co-adsorbed HO*/O* intermediates was probed. For all the studied systems the magnitudes with which varies the adsorption energies are shaped by the HO*/HOO* capability of accommodating less charge than O* (i.e according to octet rule 1e− vs. 2e−). When N concentration increases, adsorption energy of O* increases with a much higher magnitude than that of HO*/HOO* (i.e with 5 eV vs. 2.7 eV, when going from 0N to 3N). In the presence of the O* co-adsorbate, adsorption energy of intermediates on the investigated active site decrease with a much higher magnitude than when 1HO* is present as co-adsorbate (≈2 eV vs. 1 eV). The theoretical overpotential trends are evaluated using ΔGHO*-ΔGO* descriptor and are found to be significantly influenced by all these environmental changes around the active site. By applying the water stabilization effects, the activity trends remain the same as when it is not taken into account. These results reveal aspects of ORR activity variations that take place when N is clustering on graphene sheets, structures that can be possible as a function of synthesis procedures that could lead to unevenly distribution of dopants in the matrix.
KW - Graphene
KW - N-doped
KW - DFT
KW - Oxygen Reduction Reaction
KW - ORR
KW - Water splitting
KW - concentration
KW - position
KW - co-adsorbate effect
U2 - 10.1016/j.apsusc.2020.145470
DO - 10.1016/j.apsusc.2020.145470
M3 - Article
VL - 510
JO - Applied Surface Science
JF - Applied Surface Science
SN - 0169-4332
M1 - 145470
ER -