Sn (Ⅳ)-doping induced higher lattice strain and activated more lattice oxygen in the Bi2O2CO3 for boosting photocatalytic activity: Experimental and theoratical calculation study

Excellent photocatalysts should poccess satisfactory light utilization, rapid photoinduced carriers separation and aboundant active sites. Herein, a strategy for introducing both compressive strain and oxygen vacancies (OVs) into the Bi2O2CO3 lattice through Sn doping was reported. Results indicated that Sn (Ⅳ) doping induced a stronger compressive strain and more oxygen vacancies were achieved as compared with Sn (II)-doping. Besides, density functional theory (DFT) calculations unvailed that Sn (Ⅳ) doping could optimize energy band structure, reduce the leap energy of electrons, accelerate carriers separation, and improve the reactivity of the active sites. The highly-strained and oxygen-deficient 3 %sn-BOC exhibited enhanced photocatalytic performance with levofloxacin removal of 85 % and Cr (VI) reduction of 98 % within 50 min of illumination, and their reaction rate constants were 4.1 and 4.7 folds higher than that of Bi2O2CO3, respectively, much higher than the counterparts. Moreover, 14 intermediates and 3 possible degradation pathways were proposed, and most of the intermediates were less toxic than LEV. This work shows that simultaneous design of strain engineering and defect engineering via meta doping is a feasible and simple strategy to improve the photocatalytic activity of semiconductors.