Preparation Of CeO₂/ZnO Janus Hetero-nanofibers For Tetracycline Hydrochloride Degradation Via Synergistic Photo-peroxymonosulfate Strategy

Organic pollutants in wastewater have attracted extensive attention because of their resistance to degradation and potential harm to human health.According to recent studies,the photocatalytic activation of persulfate（PMS）reaction by metal oxides can produce sulfate radical（?SO₄^-）with strong oxidation activity,which can achieve efficient degradation of organic pollutants in water,and is one of the effective means of efficient green treatment of organic pollutants in water.Cerium oxide（CeO₂）,as a rare earth metal oxide semiconductor,has not only photocatalytic activity,but also can activate PMS to produce?SO₄^-radical with strong oxidation activity,which is an important catalytic material for photo PMs synergistic reaction.The improvement of its performance still faces the following problems:first,single-component CeO₂ photogenerated electrons and photogenerated holes are easy to recombine,limiting the reaction activity under photoexcitation;Second,the circulating ability of Ce³⁺/Ce⁴⁺in single-component CeO₂ is relatively weak,which affects the activation ability of PMS.Third,the high surface energy of small size powder nanomaterials in liquid phase reaction is easy to lead to agglomeration,reduce the photocatalytic activity.To solve these problems,CeO₂/Zn O and Mn-CeO₂/Zn O hollow radially ordered heterojunction nanofibers with Janus structure were prepared by electrospinning combined with atomic layer deposition technology.The radial ordered heterostructure and axial one-dimensional ultra-long structure were used to promote the separation and transport of photogenerated electron-hole pairs and improve the photocatalytic activity of CeO₂.Mn ion doping was used to promote the Ce³⁺/Ce⁴⁺cycling process and promote the activation ability of the material to PMS.The ultra-long one-dimensional structure of nanofibers and macroscopical mesh felt structure are used to improve the separability and reuse performance of the materials.The main research achievements are as follows:（1）PVP/cerium nitrate composite nanofibers were prepared by electrospinning technology,and then PVP/cerium nitrate/Zn O composite nanofibers were prepared by atomic layer deposition technology using the fiber as a hard template.Further,one-dimensional hollow CeO₂/Zn O Janus heteronode nanofibers were prepared by high temperature calcination process.The results show that:Firstly,one-dimensional hollow CeO₂/Zn O Janus heterojunction nanofibers show better catalytic activity in natural light degradation degradation TCH experiment.Janus heterostructure can effectively promote the separation of single component CeO₂ photoelectrons and holes,and improve the photocatalytic activity.Secondly,the degradation rate of Janus heterojunction nanofibers using Fenton-like reaction to degrade TCH is 1.54 times that of single component CeO₂.The heterogeneous structure of Janus improves the separation ability of photogenerated carriers and thus the activation ability of PMS.In addition,one-dimensional hollow CeO₂/Zn O Janus heterojunction nanofibers further improve the degradation efficiency of TCH under light/PMS,indicating that the material exhibits a synergistic effect between photocatalysis and Fenton-like effect.The one-dimensional structure of nanofibers and macroscopical mesh felt enhance the performance of the sample.（2）PVP/cerium nitrate/manganese acetate composite nanofibers were prepared by electrospinning technology,and then PVP/cerium nitrate/manganese acetate/Zn O composite nanofibers were prepared by atomic layer deposition technology using the fiber as a hard template,and then one-dimensional hollow Mn-CeO₂/Zn O Janus heterojunction nanofibers were prepared by high-temperature calcination.It was found that one-dimensional hollow Mn-CeO₂/Zn O Janus heterojunction nanofibers showed better catalytic activity than CeO₂/Zn O Janus heterojunction in the degradation experiment of TCH under light/PMS.The addition of Mn reduced the natural wide band gap of CeO₂,enhanced its photocatalytic activity,and may accelerate the Ce³⁺/Ce⁴⁺REDOX cycle,promoting its Fenton-like reaction.