posted on 2019-08-28, 16:36authored byHe Sun, Sisi Liu, Mengfan Wang, Tao Qian, Jie Xiong, Chenglin Yan
Rechargeable
Zn–air batteries have drawn great attention
over the past decade, but their further development will require efficient
bifunctional electrocatalysts to drive the sluggish cathodic reactions.
Although a single-atom catalyst with maximum utilization per metal
atom shows great promise, its catalytic performance is still far from
satisfactory. Here we tackle this challenge by introducing a P–O
bond to update the intrinsic activity of a single-atom site and thus
reduce the reaction overpotential of the Zn–air battery. The
critical role of the P–O bond in producing a favorable surface
electronic environment of the single-atom metal site and improving
its catalytic activity is identified with density functional theory
simulations. The P–O-doped, atomically dispersed catalyst is
shown experimentally to deliver excellent bifunctional performance,
with a remarkable half-wave potential of 0.89 V versus reversible
hydrogen electrode (vs RHE) for oxygen reduction reaction and a reversible
oxygen electrode index of 0.74 V, exceeding those of most reported
nonprecious metal catalysts. When subjected to practical application,
both aqueous and all-solid-state Zn–air batteries illustrate
superior power density and robust cyclic performance, confirming their
potential feasibility in next-generation electronic devices.