The photodegradation property and mechanism of tetracycline by persulfate radical activated In2O3@LDHs Z−scheme heterojunction

Abstract

Z − scheme heterojunctions can increase the electron transfer rate, inhibit the recombination of electrons and holes, and enable the material to possess a more vital redox ability. In this work, In2O3@ZnCr − LDHs Z − scheme heterojunction was fabricated by complexing ZnCr layered double hydroxides (LDHs) nanosheets on ho llow In2O3 nanorods and used for photocatalytic degradation of tetracycline (TC), a typical antibiotic. Under the optimal conditions of 0.6 g/L In2O3@ZnCr − LDHs, pH of 9, and reaction temperature of 40 °C, it takes 150 min for the degradation rate of TC to reach 87 %. With the addition of persulphate (PS) to form advanced oxidation processes (AOPs), the TC removal rate reached 83 % within 45 mins, and improvement was evident. When adding persulfate (PS) to form advanced oxidation processes (AOPs), the removal of TC reached 83 % within 45 min, and the improvement effect was pronounced. XPS, ESR, photoelectric performance test and DFT calculations show that the excellent photocatalytic activity is attributed to the built-in electric field in the direct Z − scheme heterojunction, which can boost the transfer of photogenerated carriers and reduce the recombination of electron-hole pairs. In addition, the heterojunction can photo-activate PS to generate more oxidative sulfate radicals, which has a synergistic effect with hydroxyl radical and superoxide radical to degrade TC. Therefore, the Z − scheme/PS − AOPs system has a potential application in antibiotic contaminant degradation.