Improved performance of Zn-doped SnO modified g-CN for visible light-driven photocatalysis.

The low-cost composite of g-CN modified by Zn-doped SnO nanoparticles was prepared for the first time in this work. The characterization results of XRD and SEM demonstrated that Zn was successfully doped into SnO. The formed Sn-O-Zn bonds and interaction between the Zn-doped SnO sample and g-CN in the composite were explored by FT-IR and XPS technologies. Photocatalytic degradation experiments showed that the as-prepared optimal composite photocatalyst displayed enhanced photocatalytic reactivity towards both dyes and antibiotics, which could degrade 85.6% of RhB and 86.8% of tetracycline within 30 and 90 min, respectively. The oxygen vacancies formed in SnO after Zn doping could capture the photogenerated electrons of g-CN, thereby promoting the separation of photogenerated electron-hole pairs, then more ·O and holes can be generated during the visible light-driven photocatalytic reaction, so that the composite of Zn-doped SnO/g-CN acquired higher photocatalytic activity and accelerated the degradation of target organics. Active species capturing experiments and ESR detection results also confirmed that ·O and holes were the main active species in the reaction process. This work developed a novel g-CN-based photocatalyst with no noble metal, low price, and high photocatalytic activity, which could provide a cost-effective and high-efficiency strategy for wastewater treatment.