The elaborately-designed Z-scheme Fe-g-C3N4/α-Fe2O3 photocatalytic platform equipping with active N-Fe-O bridges for enhanced synergistic removal of tetracycline and Cr(VI) via photoinduced electron transfer process

Abstract

Nowadays, simultaneous removal of organic pollutants and heavy metals from wastewater is still a complicated task with great challenge. Herein, a newly-designed Fe-g-C3N4/α-Fe2O3 composite with an active N-Fe-O bridge was prepared by coupling Fe-doped g-C3N4 (namely Fe-g-C3N4) and α-Fe2O3. Interestingly, the combination of Fe-g-C3N4 with α-Fe2O3 broadened the light absorption region and restrained the photoinduced electron-hole pair recombination. Meanwhile, elaborate construction of N-Fe-O bridges based on coordination interaction can reduce electrochemical impedance and facilitate electron transfer, thereby prolonging the charge lifetime. As expected, the Fe-g-C3N4/α-Fe2O3 composite displayed excellent photocatalytic performance in simultaneous removal of tetracycline (TC) and Cr(VI). More importantly, Fe-g-C3N4/α-Fe2O3-mediated electron transfer from TC to Cr(VI) also played an essential role on TC oxidation and Cr(VI) reduction under visible light. Both experimental analyses and theoretical calculations revealed that the migration route of photogenerated carriers followed a direct Z-scheme heterojunction mechanism under built-in electric field. The Fe-g-C3N4/α-Fe2O3 composite with great stability also displayed promising practical application potential. In short, the current work not only provided a highly-efficient photocatalyst with N-Fe-O bridges but also shared new insights into the simultaneous removal of organic pollutants and heavy metals.