In situ oxidation of ethylene glycol coupled with Bi2O3 epitaxial growth to prepare Bi2O3/BiOCOOH heterojunctions with oxygen vacancies for efficient photocatalytic lignin degradation

Papermaking wastewater has large output and high chemical oxygen demand (COD), which seriously affects the water environment. As a by-product of papermaking industry, lignin is the main contaminant that causes excessive COD value. Bismuth oxide is a potential catalyst for photocatalytic degradation of lignin-contained wastewater because of its high charge conduction performance and light corrosion resistance . However, the high electron-hole recombination rate and poor surface chemical state of pure Bi 2 O 3 seriously hinder the degradation efficiency. Herein, we designed an O V -Bi 2 O 3 /BiOCOOH heterojunction with oxygen vacancies and heterojunction coexisting for photocatalytic degradation of lignin. Temperature induced the oxidation of ethylene glycol into formic acid , resulting in the epitaxial growth of Bi 2 O 3 and forming a Bi 2 O 3 /BiOCOOH heterojunction. The heterojunction presents a tight interface by sharing the Bi-O tetrahedron, and provides a highway for the charge transfer. Meanwhile, the oxidation of ethylene glycol induces oxygen vacancies (O V s) on Bi 2 O 3 /BiOCOOH surface, forming charge trapping centers to promote electron transport and surface reactions. The degradation efficiency of O V -Bi 2 O 3 /BiOCOOH is approximately 3 and 16 times that of Bi 2 O 3 and BiOCOOH, respectively. The improvement of photocatalytic performance can be attributed to the synergy of heterojunction and oxygen vacancy, and the stability is attributed to covalent bonds tightly connected.