Axial ligand engineering for highly efficient oxygen reduction catalysts in transition metal–N₄ doped graphene

Abstract

Developing highly efficient and stable electrocatalysts for oxygen reduction reaction (ORR) is a challenging task in energy conversion technologies. In this work, diverse axial ligands have been used to modify...

FeNC Oxygen Reduction Electrocatalyst with High Utilization Penta‐Coordinated Sites

“…To overcome experimental limitations, the effect of O axial ligands on model FeNC systems has been calculated by density functional theory (DFT), [14,15] although the effect of other possible axial ligands on different Fe sites (pyridinic and pyrrolic) has not been fully considered. [16] Alternatively, to improve catalyst performance, the number of active sites can be increased, an approach which has shown significant progress in recent years. [17] To selectively form a high density of atomic Fe sites and avoid undesired Fe-induced carbothermal reduction, Fellinger and co-workers first identified that the high temperature pyrolytic step (800-1000 °C) should be decoupled from the Fe loading, by using a suitable N x site template.…”

FeNC Oxygen Reduction Electrocatalyst with High Utilisation Penta-coordinated sites

“…To overcome experimental limitations, the effect of O axial ligands on model FeNC systems has been calculated by density functional theory, [14,15] although the effect of other possible axial ligands on different Fe sites (pyridinic and pyrrolic) has not been fully considered. [16] Alternatively, to improve catalyst performance, the number of active sites can be increased, an approach which has shown significant progress in recent years. [17] To selectively form a high density of atomic Fe sites and avoid undesired Fe-induced carbothermal reduction, Fellinger and coworkers first identified that the high temperature pyrolytic step (800-1000ºC) should be decoupled from the Fe loading, by using a suitable Nx site template.…”

A theoretical study on the ORR electrocatalytic activity of axial ligand modified cobalt polyphthalocyanine

“…The CH 3 , benzene, benzene/NH 2 and benzene/ NO 2 ligands could improve the ORR activity of CrN 4 -Grad. 30 Zhou et al theoretically investigated the effects of axial ligands (L = -F, -Cl, -Br, -I, -OH, -O 2 , -CH 3 , -SCH 3 , -NH 2 , and -SCH 2 CH 3 ) on the ORR catalytic activity of FeN 4 , and confirmed that some axial ligands greatly enhanced the ORR catalytic activity of FeN 4 . 31 In recent years, Zhao et al reported that FePPc in which the Fe atom is axially coordinated with axial ligands (L = -F, -Cl, -Br, -I, -OH, -triethylamine (TEA), and -ethylenediamine (en)) (FePPc-L) was successfully prepared, and FePPc-I exhibited higher stability and ORR catalytic activity.…”