Exploring 1,10-Phenanthroline, 2-Picolinic Acid Metal Complexes As the Superior Single Atom Electrocatalysts toward ORR/OER/HER

Abstract

Single-atom catalyst has received extensive attention and application in recent years owing to the unparalleled high catalytic activity and maximum atom utilization, and it is also widely used in oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). In this work, the ORR/OER/HER catalytic performance of 1,10-phenanthroline, 2-picolinic acid metal complexes (named as M–N₃O, M = 3d, 4d, and 5d transition metals) is explored by density functional theory methods. We firstly compute the formation energy and dissolution potential to evaluate the thermodynamic and electrochemical stabilities for M–N₃O, respectively. The ten stable catalysts (Fe–, Co–, Ni–, Cu–, Ru–, Rh–, Pd–, Ir–, Pt–, and Au–N₃O) are screened out. Next, among the studied materials, Pd–N₃O and Ir–N₃O are expected to be potential trifunctional electrocatalysts, and the corresponding values of overpotential (η^ORR/η^OER) are respectively 0.33/0.48 and 0.62/0.29 V, and the ΔG_*H values are 0.04 and –0.14 eV. In addition, the deformation charge density and density of states analyses reveal that the superb catalytic activity can be ascribed to electron transfer from metal to O atoms and orbitals hybridization between metal and O atoms near Fermi level. This work would open a new perspective to design the trifunctional electrocatalyst with ultra-high activity and stability.