Photocatalytic Degration Of PET Fibers And Hydrogen Evolution Properties By The Flexible Metal Phosphide/Carbon Composite Nanofiber Film

The harm of microplastic pollution to ecosystems is a global concern.The largest proportion of microplastic pollution is caused by microfibers from textiles.This is because textiles release fibers into the environment during the production,use,and waste treatment.Microplastic fibers（<5 mm）are found in ecosystems worldwide and can absorb and accumulate organic pollutants and enter the food chain,with serious impacts on human health and ecosystems.Among the many textile fiber materials,polyester（PET）is the most commonly used in the textile industry.Photocatalysis technology is a green and effective method to solve the problem of microplastic fiber pollution,but the reported photocatalysts have the problems of high preparation costs and difficult recovery.This paper mainly studies the preparation of a flexible,efficient,and recyclable composite nanofiber membrane,which is used as a photocatalyst for the photocatalytic degradation of PET microfibers while generating hydrogen（H₂）in the degradation process.The results are as follows:（1）Through electrospinning,hydrothermal,and low-temperature phosphating,the flexible Ni₅P₄/Ti O₂/C composite nanofiber film photocatalyst for photocatalytic degradation of PET microfibers was created.The composite nanofiber film’s morphology and structural analysis revealed that Ni₅P₄ nanosheets were uniformly coated on the Ti O₂/C composite nanofibers,improving the film’s capacity to absorb light and effectively preventing photogenerated carrier recombination.The hydrogen production of the Ni₅P₄/Ti O₂/C composite nanofiber film is improved to 76.668)7)₂2)^-1_{（7）,which is 3.2 times that of the Ti O2/C composite nanofiber film.The Ni5P4/Ti O2/C composite nanofiber film has a catalytic degradation effect on PET microfibers.After 12 h of photocatalytic reaction,the surface of the PET microfibers became rough,and the weight loss reached 6.23%.And PET microfibers were degraded into small organic molecules such as formate and glyoxal.（2）To further increase the photocatalytic activity,Co was added to the Ni5P4/Ti O2/C composite nanofiber film by hydrothermal and low-temperature phosphatizing methods.By analyzing the morphology and structure,it was found that the morphology and crystallization of Ni5P4 were not affected by the introduction of the 7.5%Co element.At the same time,there is a strong electronic interaction between Co and Ni5P4,which can regulate the electronic environment,and the presence of bimetallic phosphide is conducive to the generation of more active sites,thereby improving the catalytic activity.The hydrogen production of the Ni0.93Co0.07Px/Ti O2/C composite nanofiber film is 1.58times that of the Ni5P4/Ti O2/C composite nanofiber film.After 12 h of catalysis,the surface roughness of PET microfibers was increased,the groove was deeper,and the molecular weight was decreased,indicating that the catalytic reaction can change the molecular structure of PET microfibers,which is conducive to the catalyst’ability to further destroy PET microfibers and accelerate their degradation.（3）In order to further improve the catalytic performance of composite nanofiber membrane photocatalysts.Ce O2 was added in the Ni Co Px/Ti O2/C composite nanofiber film.The Ce O2-Ni Co Px/Ti O2/C composite nanofiber film was obtained by changing the hydrothermal and low-temperature phosphating processes and using Ti O2/C composite nanofiber film as substrate.By analyzing the morphology and structure of Ce O2-Ni Co Px/Ti O2/C composite nanofibers,it is found that Ti O2/C composite nanofibers are coated with nanowires and have pores.And it contains a variety of crystal forms corresponding to different crystal faces that will form rich heterogeneous interfaces or active centers.The addition of Ce O2 can expand the light absorption range of composite nanofiber membranes,but also encourage electron and hole separation,which is essential to enhancing catalytic activity.Finally,the hydrogen production of the Ce O2-Ni Co Px/Ti O2/C composite nanofiber film is improved,and the catalyst reached 127.188}7)₂2)^-1₍（7） at 12 h,which is 1.66 times that of the Ni₅P₄/Ti O₂/C composite nanofiber film.At the same time,it has a degradation effect on PET microfibersTherefore,in this paper,a variety of flexible,efficient,recyclable and cost-effective composite nanofiber membrane photocatalysts were prepared for the catalytic degradation of PET microfibers and hydrogen production.Although the catalyst’s stability needs to be increased and PET microfibers’ability to degrade is limited,it has a certain reference value for addressing the issue of microplastic pollution in an eco-friendly and sustainable manner.