Rare‐Earth Lanthanum Tailoring Mott–Schottky Heterojunction by Sulfur Vacancy Modification as a Bifunctional Electrocatalyst for Zinc–Air Battery
Zhou Yang, Jingjing Yang, Chengbin Yu, Jirong Bai, Xinjie Xie, Nan Jiang, Bingbing Chen, Shuang Dong, Meng Xiang, Hengfei Qin
Abstract
Zinc–air battery (ZAB) has considerable potential to be applied in the energy storage field. The main commercial electrocatalysts are Pt/C and RuO 2 , which are expensive and cannot possess good bifunctional electrocatalytic activities including oxygen reduction reaction and oxygen evolution reaction. Herein, the rare‐earth metal lanthanum is first constructed to be a Mott–Schottky heterojunction, and the S vacancy is introduced into the Mott–Schottky heterojunction. The so‐obtained La/La 2 O 2 S 1− x shows excellent bifunctional electrocatalytic activity with Δ E of 0.68 V, which is superior to La/La 2 O 2 S without S vacancies and the commercial Pt/C + RuO 2 system. In addition, the La/La 2 O 2 S 1− x is assembled into ZABs, showing a high open power density of 212 mW cm −2 , and a large specific capacity of 707 mAh g −1 , as good cycle stability. The density functional theory calculations reveal the tailoring effect of S vacancy on the Schottky barrier to control the electron transfer concentration and ameliorate over‐strong adsorption, which blocks the reflux of electrons and promotes the unidirectional flow of electrons. In addition, the S vacancy modulates the electron cloud of La‐4 f orbit and makes the electrocatalytic pathway closer to the ideal pathway.