非均相光芬顿技术的关键在于过氧化氢(H2O2)的高效生成。在这里,合成了一种新设计的具有异质结构的ZnO/ZnIn2S4复合材料。受益于内置电场的形成,抑制了光生电子和空穴的复合,降低了界面电荷转移电阻。重要的是,在ZnIn2S4中嵌入ZnO可以改善疏水性并形成微观三相界面,从而提高了对O2的捕获能力并为O2还原反应的发生提供了便利。更有趣的是,ZnO/ZnIn2S4复合材料中ZnIn2S4的存在可以降低关键中间体(OOH*)形成的吉布斯自由能(ΔG),这将加速H2O2的生成。因此,ZnO/ZnIn2S4复合材料在光催化H2O2生产中表现出优异的性能,在可见光照射下,60分钟内的最高产量约为897.6μmol/g/h。光诱导载流子的转移遵循S-方案型机制。光生空穴可以被药物残留物捕获(即,双氯芬酸钠)以加速H2O2的产生,而生成的H2O2可以与Fe2+结合,构建光-Fenton体系,实现双氯芬酸钠的高级降解,这主要与OH•的形成有关。此外,产生的H2O2可用于进行病原菌的灭活。总之,为今后的研究提供有价值的参考。
The key to heterogeneous photo-Fenton technology lies in the efficient generation of hydrogen peroxide (H2O2). Herein, a newly-designed ZnO/ZnIn2S4 composite with heterostructure is synthesized. Benefiting from the formation of built-in electric field, the recombination of photoinduced electrons and holes is suppressed and interfacial charge transfer resistance is reduced. Importantly, the embedding of ZnO in ZnIn2S4 can improve the hydrophobicity and create microscopic three-phase interface, thereby boosting the capture capability for O2 and providing the convenience for the occurrence of O2 reduction reaction. More interestingly, the existence of ZnIn2S4 in the ZnO/ZnIn2S4 composite can reduce the Gibbs free energy (ΔG) of key intermediate (OOH*) formation, which will accelerate the generation of H2O2. As a result, the ZnO/ZnIn2S4 composite displays excellent performance in photocatalytic H2O2 production, and the highest yield was about 897.6 μmol/g/h within 60 min under visible light irradiation. The transfer of photoinduced carriers follows the S-scheme type mechanism. The photogenerated holes can be captured by drug residues (i.e., diclofenac sodium) to accelerate H2O2 production, while generated H2O2 can combine with Fe2+ to construct photo-Fenton system for achieving the advanced degradation of diclofenac sodium, which was mainly related to the formation of OH•. Furthermore, generated H2O2 can be applied for performing the inactivation of pathogenic bacteria. In short, current work will provide a valuable reference for future research.