Preparation Of Hollow Covalent Triazine Frameworks Spheres And Study On Their Photocatalytic Water Splitting

As a new type of porous organic semiconductor materials,covalent triazine frameworks（CTFs）are widely used in the fields of gas adsorption and separation,photocatalysis and so on.In order to improve the performance of application of CTFs,some strategies are often used to improve their corresponding performances.Morphology regulation is one of the effective methods.At present,the studies on the morphology regulation of CTFs are mainly focused on 2D nanosheets and open 3D hollow structures,while the studies on hollow spherical morphologies have not been achieved.The main reason is that the current method for preparing hollow polymer spheres is generally the hard template method.Once the template is removed,the structure easily collapses,and the traditional preparation methods of synthesis conditions of CTFs are harsh,which is not conducive to control morphology.Therefore,the preparation of CTFs with controllable morphology is still a challenge.This thesis mainly includes two aspects of exploring the preparation method of hollow CTFs spheres and studying the photocatalytic water splitting performance of hollow CTFs spheres.At first,the preparation method of hollow CTFs spheres was established.Taking CTF-HUST-1 as a research target,exploring a method for preparing hollow CTFs spheres,that is,a method of combining the hard template method with a low-temperature polycondensation method and adding monomers in two steps.The chemical structure,pore structure and morphology of the prepared samples were tested and characterized.The experimental results show that this way can successfully prepare hollow CTFs spheres.Moreover,it is found that when keeping the amount of monomers constant and increasing the amount of template,the morphology of CTFs will gradually from hollow spherical morphology collapse to an irregular bowl-like shape as the shell thickness decreases.This study provides an effective way for the morphological regulation of CTFs.Next,the photocatalytic water splitting performance of the hollow CTFs spheres was further investigated.The photocatalytic half water splitting hydrogen evolution performance of hollow CTF-HUST-1 spheres and hollow CTF-HUST-2 spheres,and the overall water splitting performance of hollow CTF-HUST-1 spheres which are loaded by the co-catalysts in inside and outside surface are studied respectively.The hollow spherical morphology can effectively improve the photocatalytic water splitting performance of CTFs.The photocatalytic performance of hollow CTF-HUST-1 spheres and hollow CTF-HUST-2 spheres are about 4 times and 3 times of the performance of the bulk CTF-HUST-1 and CTF-HUST-2,respectively.Furthermore,a preliminary exploration of the overall water splitting performance of hollow CTF-HUST-1 spheres loaded with Pt and Ru O₂ inside and outside of the hollow CTFs spheres surface.These results show that the spatial separation of O₂ and H₂ co-catalysts can promote the spatial separation of the redox active sites of water,thereby improving the photocatalytic overall water splitting performance.