Sulfur atom occupying surface oxygen vacancy to boost the charge transfer and stability for aqueous Bi2O3 electrode

Abstract

Oxygen vacancies (O_v) within metal oxide electrodes can enhance mass/charge transfer dynamics in energy storage systems. However, construction of surface O_v often leads to instability in electrode structure and irreversible electrochemical reactions, posing a significant challenge. To overcome these challenges, atomic heterostructures are employed to address the structural instability and enhance the mass/charge transfer dynamics associated with phase conversion mechanism in aqueous electrodes. Herein, we introduce an atomic S–Bi₂O₃ heterostructure (sulfur (S) anchoring on the surface O_v of Bi₂O₃). The integration of S within Bi₂O₃ lattice matrix triggers a charge imbalance at the heterointerfaces, ultimately resulting in the creation of a built-in electric field (BEF). Thus, the BEF attracts OH⁻ ions to be adsorbed onto Bi within the regions of high electron cloud overlap in S–Bi₂O₃, facilitating highly efficient charge transfer. Furthermore, the anchored S plays a pivotal role in preserving structural integrity, thus effectively stabilizing the phase conversion reaction of Bi₂O₃. As a result, the S–Bi₂O₃ electrode achieves 72.3 mA h g⁻¹ at 10 A g⁻¹ as well as high-capacity retention of 81.9% after 1600 cycles. Our innovative S–Bi₂O₃ design presents a groundbreaking approach for fabricating electrodes that exhibit efficient and stable mass and charge transfer capabilities. Furthermore, it enhances our understanding of the underlying reaction mechanism within energy storage electrodes.