Abstract Wastewater treatment challenges by conventional methods have necessitated the need for alternative/complementary methods that are environmentally benign and efficient especially toward recalcitrant organic pollutants. In this regard, a novel photoanode consisting of a p-n MoS2-SnO2 heterojunction anchored on expanded graphite (EG) was fabricated and employed in the photo-electrocatalytic degradation of ciprofloxacin, a pharmaceutical pollutant, in water using a current density of 0.010 A cm−2. The photoanode material was characterised with transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), Raman spectroscopy and X-ray diffraction (XRD) to confirm that the nanocomposite was successfully prepared. Photoelectrochemical studies were carried out with cyclic/linear sweep voltammetry and chronoamperometry. The removal efficiency of the photo-electrocatalytic cell was determined on a UV–Visible spectrophotometer and the extent of mineralisation was measured by a total organic carbon analyser. The results obtained revealed that the SnO2 particles are nanosheets while the MoS2 particles are hierarchical microspheres having nanosheets of MoS2, and they were anchored on the interlayers of the EG sheets. Also, the p-n MoS2-SnO2 heterojunction anchored on expanded graphite (EG) was found to be photoactive and displayed a better removal efficiency and mineralisation in comparison to EG, SnO2-EG and MoS2-EG electrodes. This may be due to the formation of the MoS2-SnO2 p-n heterojunction in the MoS2-SnO2/EG nanocomposite which enhanced the light harvesting ability of the material resulting in its improved photo-electrocatalytic performance. Hence the MoS2-SnO2/EG is potentially a good photoelectrode which may be beneficial for a photo-electrocatalytic treatment of industrial wastewaters and other photo-electrocatalytic applications.

中文翻译：

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膨胀石墨负载的 pn MoS2-SnO2 异质结纳米复合电极用于增强光电催化降解药物污染物

摘要 传统方法的废水处理挑战使得需要对环境无害且有效的替代/补充方法，尤其是对于顽固的有机污染物。在这方面，制造了一种由锚定在膨胀石墨 (EG) 上的 pn MoS2-SnO2 异质结组成的新型光电阳极，并将其用于使用 0.010 A cm− 的电流密度在水中光电催化降解环丙沙星（一种药物污染物）。 2. 通过透射电子显微镜（TEM）、扫描电子显微镜（SEM）、能谱仪（EDS）、拉曼光谱和X射线衍射（XRD）对光阳极材料进行表征，证实纳米复合材料制备成功。用循环/线性扫描伏安法和计时电流法进行光电化学研究。在紫外-可见分光光度计上测定光电催化电池的去除效率，并通过总有机碳分析仪测量矿化程度。获得的结果表明，SnO2 颗粒是纳米片，而 MoS2 颗粒是具有 MoS2 纳米片的分级微球，它们锚定在 EG 片的夹层上。此外，与 EG、SnO2-EG 和 MoS2-EG 电极相比，固定在膨胀石墨 (EG) 上的 pn MoS2-SnO2 异质结具有光活性，并显示出更好的去除效率和矿化。这可能是由于在 MoS2-SnO2/EG 纳米复合材料中形成了 MoS2-SnO2 pn 异质结，增强了材料的光捕获能力，从而提高了其光电催化性能。因此，MoS2-SnO2/EG 是一种潜在的良好光电极，可能有利于工业废水的光电催化处理和其他光电催化应用。