Two-Dimensional Metal Hexahydroxybenzene Frameworks as Promising Electrocatalysts for an Oxygen Reduction Reaction

Exploring efficient and inexpensive electrocatalysts for a cathode oxygen reduction reaction (ORR) is essential to the large-scale commercialization of fuel cells. Via first principles calculations, we systematically investigated the electrocatalytic performance of two-dimensional (2D) metal-hexahydroxybenzene frameworks (M-3(C6O6 )(2), where M denotes Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, and Pd) for ORR. Owing to the sufficient Jr-electron conjugation and effective interaction between the metal and the organic linkers, the studied 2D M-3(C6O6)(2) are all metallic with good conductivity for electron transfer. Interestingly, the catalytic activity of M-3(C6O6)(2) turns out to be dependent on the interaction strength between the ORR intermediates and the metal complex (MO4) and can be modified by changing the metal atoms with different d-electron occupations. Remarkably, while 2D Mn-3(C6O6)(2), Fe-3(C6O6)(2), and Rh-3(C6O6)(2) show a rather good ORR activity rivaling that of Pt, 2D Co-3(C6O6)(2) presents a much higher onset potential than that of Pt. Our investigations provide important insights into designing and screening efficient ORR catalysts.