POM-Assisted Preparation Of Mesoporous Polymer/Carbon-Based Materials And Their Electrochemical Performance

Mesoporous materials are characterized by high specific surface area and rich functional sites,making them widely applicable in fields such as catalysis,sensing,biomedicine,and energy storage.Soft templates have been extensively used in the preparation of mesoporous materials,including mesoporous metal oxides,conducting polymers,and derived carbon materials.However,the above strategy requires the formation of suitable interactions between the precursor and the soft template,and for those precursors with weak interaction with the soft template,it is still difficult to directly construct the mesoporous structure.Introducing a"bridge unit"between the template and the precursor is a promising strategy to address this issue.The polyoxometallate（POM）is a class of molecular clusters formed by transition metal ions and oxygen-containing ligands,which is rich in oxygenate coordination sites on the surface and can assist in complexation and co-assembly of templating agents with organic precursors under the action of coordination and hydrogen bonding to construct novel mesoporous materials.Meanwhile,the bottom-up co-assembly of POM and monomers can achieve the complementary combination of organic and inorganic phases at the molecular scale,which can further enhance the stability and application performance of the obtained hybrid functional materials.In this thesis,mesoporous polymer-based materials were prepared in the solution by using block copolymers as soft templates,and their electrochemical properties were further explored.The main research contents and results are as follows:1.POM-assisted preparation of mesoporous supersturcutred polymer and their derivatives for sodium-iodine batteriesThis work presents a new strategy to introduce POM as a bifunctional bridge unit for the controlled preparation of a series of mesoporous nanospheres with different compositions and morphologies.Among them,a co-assembly method based on ammonium molybdate tetrahydrate（AMT）leads to mesoporous polymers with highly wrinkled walls（Mo-m PPD）,forming spherical morphology with about 208 nm diameter and dentritic-like mesochannels（～18 nm）.Heat treatment leads to porous nitrogen-doped carbon hybrid materials,uniformly loaded with ultrafine molybdenum nitride clusters of 2-5 nm size（γ-Mo₂N/m NC）.Further loaded with I₂ and used as the cathode material for sodium-iodine batteries,I₂@γ-Mo₂N/m NC exhibits high discharge capacity(0.5 A g^-1,235 m Ah g^-1),excellent rate performance and cycling stability.Meanwhile,density functional theory calculations demonstrate that nitrogen-doped carbon andγ-Mo₂N have strong adsorption ability on polyiodide,which can effectively mitigate the dissolution of polyiodide in organic electrolyte and shuttle effect.2.POM-assisted preparation of sandwich-structured rGO-based mesoporous polymers and their performance in zinc-iodide batteriesBased on the first work,two-dimensional mesoporous nanosheets（Mo-m PDAN@rGO）with sandwich structure were prepared by co-assembling soft template（F127）with hard template（rGO）and introducing POM and 1,5-diaminonaphthalene（1,5-DAN）.The materials have uniform mesoporous pore channels（18-20 nm）,high specific surface area(75 m² g^-1),and can be used as an effective cathode material for zinc-iodine batteries after subliming iodine.It exhibits a high discharge capacity(245m Ah g^-1 at 0.2 A g^-1)and long-cycle stability(84.5%capacity retention at a current density of 5 A g^-1 for 3000 cycles).