One-step synthesis of citric acid-modified ultrasmall Cu2O nanoparticles with rich oxygen vacancies for highly efficient photodegradation of tetracycline under visible light

Nowadays, the occurrence of tetracycline (TC) in aquatic ecosystems has aroused considerable concerns. In this work, citric acid (CA)-modified Cu 2 O nanoparticles (NPs) synthesized by one-step method, featuring ultrasmall particle size, good visible light response, and rich oxygen vacancy, exhibited remarkable photocatalytic performance and excellent stability for the TC degradation under visible light. The as-prepared Cu 2 O NPs (4.8 nm) could degrade 95 % of TC within 5 min at pH = 5, extraordinarily superior to the currently reported Cu 2 O-based photocatalysts. The dominant reactive species in the degradation process were superoxide radicals (•O 2 − ) and electron hole (h + ). The modification with CA onto the Cu 2 O surface could promote the separation and transfer of photogenerated electron-hole pairs and the transformation of O 2 to •O 2 − , thereby improving the photocatalytic performance. This work reveals that the CA-modified Cu 2 O NPs have great potential to serve as an effective solution for the remediation of environmental pollution.