Rare‐Earth Lanthanum Tailoring Mott–Schottky Heterojunction by Sulfur Vacancy Modification as a Bifunctional Electrocatalyst for Zinc–Air Battery

Abstract

Zinc–air battery (ZAB) has considerable potential to be applied in the energy storage field. The main commercial electrocatalysts are Pt/C and RuO2, 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/La2O2S1−x shows excellent bifunctional electrocatalytic activity with ΔE of 0.68 V, which is superior to La/La2O2S without S vacancies and the commercial Pt/C + RuO2 system. In addition, the La/La2O2S1−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‐4f orbit and makes the electrocatalytic pathway closer to the ideal pathway.

Keywords

• bifunctional electrocatalysts
• lanthanum
• Mott–Schottky heterojunctions
• S vacancies
• zinc–air batteries