In this study, a g-C3N4/Ag3PO4 composite Z-heterojunction photocatalyst was prepared with a simple in situ deposition method, and was first applied to the degradation of Ofloxacin (OFX). When the theoretical g-C3N4 to Ag3PO4 mass ratio was 1:10 (denoted as AC-10), the OFX degradation was optimal, and the degradation efficiency reached 71.9 % within 10 min. Steady state fluorescence emission spectroscopy (PL), electrochemical impedance spectroscopy (EIS), transient photocurrent (I-t) and N2 adsorption-desorption (BET) studies showed that AC-10 had the best charge separation efficiency and highest specific surface area. Additionally, the effects of AC-10 dosage, OFX concentration, pH value, anions, humic acid and water source on the degradation process were also studied. A cycling experiment showed that AC-10 exhibited good stability. Three-dimensional excitation-emission matrix spectroscopy (3D EEMs), LC-MS data and ECOSAR models were used to explore the process for degradation of OFX and predict the biotoxicities of byproducts, and these results indicated that the catalyst was environmentally friendly. In addition, electron spin resonance (ESR) experiments and capture of the active species showed that photogenerated holes (h+) played a major role in the reaction. Finally, the optical properties and the energy band structure of the catalyst were analyzed by UVvis diffuse reflectance spectroscopy (DRS) and Mott-Schottky (M-S) methods, and a Z-type heterojunction charge transfer mechanism was proposed.

中文翻译：

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g-C3N4/Ag3PO4复合Z型光催化剂的制备及光催化降解氧氟沙星：降解性能、反应机理、降解途径及毒性评价


本研究采用简单的原位沉积方法制备了g-C3N4/Ag3PO4复合Z-异质结光催化剂，并首次应用于氧氟沙星（OFX）的降解。当g-C3N4与Ag3PO4理论质量比为1:10（记为AC-10）时，OFX降解效果最佳，10 min内降解效率达到71.9%。稳态荧光发射光谱(PL)、电化学阻抗谱(EIS)、瞬态光电流(It)和N2吸附-脱附(BET)研究表明AC-10具有最好的电荷分离效率和最高的比表面积。此外，还研究了AC-10用量、OFX浓度、pH值、阴离子、腐植酸和水源对降解过程的影响。循环实验表明AC-10表现出良好的稳定性。利用三维激发发射矩阵光谱（3D EEM）、LC-MS数据和ECOSAR模型探索OFX的降解过程并预测副产物的生物毒性，结果表明该催化剂是环境友好的。此外，电子自旋共振（ESR）实验和活性物质的捕获表明光生空穴（h+）在反应中发挥了主要作用。最后，通过紫外可见漫反射光谱（DRS）和莫特肖特基（MS）方法分析了催化剂的光学性质和能带结构，并提出了Z型异质结电荷转移机制。