Plasma-Treated Ultrathin Ternary FePSe<sub>3</sub> Nanosheets as a Bifunctional Electrocatalyst for Efficient Zinc–Air Batteries
Yanan Hao, Aijian Huang, Silin Han, Hongjiao Huang, Junnan Song, Xiaoli Sun, Zhiguo Wang, Linlin Li, Feng Hu, Jianjun Xue, Shengjie Peng
Abstract
Developing novel bifunctional electrocatalysts with advanced oxygen electrocatalytic activity is pivotal for next-generation energy-storage devices. Herein, we present ultrathin oxygen-doped FePSe 3 (FePSe 3 –O) nanosheets by Ar/O 2 plasma treatment, with remarkable surface atom reorganization. Such surface atom reorganization generates multiple crystalline–amorphous interfaces that benefit the kinetics of oxygen evolution reaction, achieving a low overpotential of only 261 mV at 10 mA cm –2 with a small Tafel slope of 41.13 mV dec –1 . Density functional theory calculation indicates that oxygen doping can also modulate the electrical states at the Fermi level with a decreased band gap responsible for the enhanced electrocatalytic performance. Such unique FePSe 3 –O nanosheets can be further fabricated as the air cathode in rechargeable liquid zinc–air batteries (ZABs), which deliver a high open circuit potential of 1.47 V, a small charge–discharge voltage gap of 0.80 V, and good cycling stability for more than 800 circles. As a proof of concept, the flexible solid-state ZABs assembled with FePSe 3 –O nanosheets as cathode also display a favorable charge–discharge performance, durable stability, and good bendability. This work sheds new insights into the rational design of defect-rich ternary thiophosphate nanosheets by plasma treatment toward enhanced oxygen electrocatalysts in metal–air batteries.