Quantum Confinement and Defect Engineering Mediated “Two Birds with One Stone” Strategy for Co/Bi Self-Regeneration and Effective Photogenerated Carrier Separation

Abstract

Traditional semiconductors face a challenge where photo-generated electrons (e-) mainly accumulate in the bulk, leading to electron-hole recombination and inefficient catalysis. Herein, a novel CoBiOx (CBO) semiconductor quantum dots (QDs) have been synthesized through the in situ partial substitution of Bi atoms in Bi3O4Cl with Co atoms. By embedding CBO into a defect-rich biochar (NBC) framework, the fabricated NBC@CoBiOx (NCBO) exhibited excellent quantum confinement and defect-induced effects, which could mediate “two birds with one stone” strategy that not only facilitates the transitions of bulk-phase electrons to surface electrons, enhancing charge carrier separation, but also promotes the capture of surface electrons by the Co/Bi dual active sites, enabling self-regeneration of mental sites. The presence of Co and Bi active sites synergistically promotes the decomposition of peroxymonosulfate (PMS) into reactive oxygen species (ROS), achieving efficient degradation of Tetrachloroguaiacol (TeCG). Density Functional Theory (DFT) calculations confirm that the NCBO system exhibits superior electron transfer flux and strong affinity for PMS, with the Co sites playing a pivotal role in the decomposition of PMS towards the thermodynamically favorable generation of singlet oxygen (1O2). Simulated application results suggest that the unique self-regenerating feature of the NCBO photo-Fenton-like system holds promising potential in future wastewater treatment.

Keywords: CoBiOx, Quantum confinement, Carbon defect, Self-regeneration, Photo-Fenton-like.