Construction of TiO2@C/g-C3N4 and Its Photocatalytic Degradation Performance of Tetracycline
The binary heterojunction photocatalyst TiO2@C/g-C3N4 was prepared by one-step calcination method.The photocatalytic degradation of tetracycline(TC)by TiO2@C/g-C3N4 under simulated visible light irradiation was investigated by XRD,TEM,XPS and band structure analysis.The characterization results show that TiO2@C is attached to the surface of g-C3N4,and traditional type Ⅱ heterojunction is formed between them.The experimental results show that the TiO2@C/g-C3N4 catalyst has higher photocatalytic activity than g-C3N4 and TiO2@C.Under the conditions of tetracycline concentration of 20 mg∙L-1 and GTC-2(Ti3C2 weight is 0.06 g)addition of 0.3 g,the TC removal rate can reach 87.3%after 80 min irradiation by photocatalytic lamp.The rate constant was 0.026 min-1.After 5 cycles of experiment,the removal rate of TC gradually decreased from 87.3%to 80%,showing good stability and reusability.The redox reactions during the photocatalytic degradation of tetracycline by GTC-2 are carried out on the surface of TiO2@C and g-C3N4 respectively.The highly close contact surface between TiO2@C and g-C3N4 forms a type Ⅱ heterojunction,which realizes the rapid separation of electrons and holes,reduces the recombination rate of the two in the catalyst,and improves the catalytic performance.The results of electron spin magnetic resonance spectroscopy(EPR)showed that superoxide radical(·O2-),hole(h+)and hydroxyl radical(·OH)were the main active substances in the degradation of tetracycline.
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