Oxygen vacancy induced strong interfacial electric field for boosting photocatalytic degradation of tetracycline

Heterojunction construction is an effective strategy to improve the photocatalytic performance of a single semiconductor, but the interfacial electric field (IEF) is often weak, and this strategy cannot solve the problem of few surface reactive sites, resulting in limited catalytic activity improvement of heterojunctions. In this work, we constructed a Z-scheme structure with oxygen vacancies (Ovs) by in situ growth of OV-rich BiOI (Vo-BiOI) crystals on the surface of CTAB-modified g-C3N4 (BCN) flakes. The IEF between BCN and Vo-BiOI offers a strong driving force to accelerate direct Z-scheme charge transfer evidenced by in-situ Kelvin probe force microscopy (KPFM) and theoretical calculations. In addition, the BCN/Vo-BiOI possesses a high adsorption and activation capacity of pollutant molecules due to the surface CTAB modification on g-C3N4 and introducing Ovs on the surface of BiOI. Thus, this unique Z-scheme heterojunction generates more •OH and •O2- for tetracycline (TC) degradation, and the degradation rate reaches 0.0260 min−1, which is 32.5 times that of pure g-C3N4. Output of this work may provide a good avenue for development of efficient and versatile novel photocatalytic materials.