Mechanisms of the Higher Catalytic Activity of Polymer Forms over Complexes for Non-pyrolytic Mono-1,10-phenanthroline-Coordinated Cu 2+ (Cu-N 2 Type) in an Oxygen Reduction Reaction

In this paper, we have thoroughly investigated the ORR mechanism of non-pyrolytic mono-1,10-phenanthroline-coordinated Cu (Cu-N type) complexes and polymers by molecular dynamics and quantum mechanics calculation. In contrast to the complex-catalyzed ORR, which follows a direct four-electron pathway along intermediates of Cu(I)-Phen, the polymer-catalyzed ORR follows an indirect four-electron pathway by intermediates of Cu(II)-Phen. By analyzing the structure, spin population, electrostatic potential (ESP), and density of states, we confirmed that the higher ORR catalytic activity of the polymer is due to the conjugation effect of coplanar phenanthroline and Cu(II) in the planar reactants or at the base of the square-pyramidal intermediates. The conjugation effect allows the highest ESP to be located near the active center Cu(II), while the lower ESPs are distributed on the phenanthroline, which is very favorable for the reduction current. This will serve as a theoretical foundation for the development of new highly efficient ORR non-pyrolytic CuN polymer catalysts.