Leveraging oxygen-vacancy-rich Yb-MnO2/N-carbon quantum dots heterostructure for solar light-driven tetracycline detoxification and antibiotic-resistant bacteria inactivation

Microbial pollution and antibiotic contamination can pose a serious threat to human health. The rational development of efficient and low-cost methods is critical to solving these problems. In this study, novel Z-scheme heterojunctions consisting of Yb-MnO2 and nitrogen-doped carbon quantum dots (N-CQDs) were fabricated to achieve efficient photocatalytic degradation of tetracycline (TC) and the destruction of bacteria (Escherichia coli used as a model). Results showed that the Yb-doping strategy improves the characteristics of host MnO2 by weakening the lattice interface and increasing its surface area. Compared with Yb-MnO2, Yb-MnO2/N-CQDs heterostructures exhibited superior photocatalytic activity in TC degradation under simulated solar light. The remarkable photocatalytic and mild oxidation abilities of Yb-MnO2/N-CQDs led to an impressive 97.88% removal rate of TC. Additionally, the structure displayed robust resistance to various ions and broad pH levels. Notably, the Yb-MnO2/N-CQDs heterostructures exhibited excellent bactericidal activity, with no observed bacterial resistance even after 20 consecutive trials. Furthermore, quenching experiments demonstrated that O-1(2) and O-2(-) were the primary radicals involved in the Yb-MnO2/N-CQDs-based photocatalysis process. The remarkable photocatalytic activity of Yb-MnO2/N-CQDs can be attributed to two key factors. Firstly, the large surface area and abundant oxygen defects provide rich active sites for reactant degradation. Secondly, the Z-scheme heterojunctions formed between Yb-MnO2 and N-CQDs effectively facilitate the separation of photogenerated electron-hole pairs and increase the reduction/oxidation potentials for reactive oxygen species generation. This study presents a promising novel photocatalyst for the facile and energy-saving treatment of antibiotic and microbial pollution, and it may provide new insight into the design of highly efficient heterogeneous photocatalysts.