Anisotropic Surface Modulation of Pt Catalysts for Highly Reversible Li–O2 Batteries: High Index Facet as a Critical Descriptor

The surface structure of solid catalysts has been regarded as a critical descriptor for determining the catalytic activities in various applications. However, structure-dependent catalytic activities have been rarely understood for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) within Li–O2 batteries. Here, we succeeded in the preparation of a Pt catalyst with an anisotropic structure and demonstrated its high catalytic activity in nonaqueous Li–O2 batteries. The cathode incorporating Pt exposed with high-index {411} facets showed greatly enhanced ORR and OER performance in comparison to commercial Pt/C cathode. The anisotropic Pt catalyst improved ORR activity with a large capacity of 12 985 mAh gcarbon–1, high rate performance, and stable cyclic retention up to 70 cycles with the capacity limited to 1000 mAh gcarbon–1. Furthermore, the anisotropic Pt catalyst exhibited high round-trip efficiency of ∼87% with a low OER potential (3.1 V) at a current density of 200 mA gcarbon–1. Our first-principles calculations revealed that the high-index facets, which contain step edge, kink, and ledge sites, are significantly more reactive than the low-index facets in terms of surface energy and O-binding energy.