Design of core-shelled g-C3N4@ZIF-8 photocatalyst with enhanced tetracycline adsorption for boosting photocatalytic degradation

Confining active species and intermediates in a limited spatial is critical to driving pollutant transformation involving successive reactions for boosting degradation. Herein, core–shell g-C3N4@ZIF-8 were prepared by exfoliating-wrapping of g-C3N4 via ZIF-8 in-situ growth. XRD, SEM, TEM, and EDX mapping demonstrate the inclusion of curled g-C3N4 sheets in ZIF-8. UV–vis, PL, FTIR, and XPS confirm the coordination of TC with Zn of ZIF-8. Steady-transient PL, EIS and transient photocurrent response indicate that the combination of two materials favors the carriers’ separation and transfer. Further band analysis suggests that interfacial band bending of g-C3N4 promotes the separation of electron-hole and electron diffusion toward ZIF-8. As result, the optimized g-C3N4@ZIF-8 exhibits a superior TC degradation rate constant (k = 0.068 min−1), 4.8 times higher than that of g-C3N4 (k = 0.014 min−1), and enhanced TC removal rate of 87.6% higher than g-C3N4 (58.6%). Also, the optimized material shows superior degradation rate and removal efficacy in RhB (99.3%) and Cr (VI) (96.6%) in surface water. The investigations on active species and degradation routes (EPR, LC-MS) reveal that synergetic effects of ZIF-8 confined g-C3N4 facilitate the formation of oxygen radicals (O2−) and their transformation toward singlet oxygen (1O2) for boosting TC degradation.