Construction And Photocatalytic Performance Of Porphyrin-Based Organosilicon Skeleton Composites

Compared to traditional organic reactions,photocatalytic organic reactions offer advantages such as mild reaction conditions,high product selectivity,and environmentally friendly processes that align with the development needs of green chemistry.However,achieving efficient photocatalytic organic reactions in water systems remains a technical challenge in green chemistry.Porous organosilicon skeleton material offers several advantages,including a high specific surface area,adjustable structure,and flexible hydrophilic/hydrophobic control.Addressing three fundamental scientific challenges:enhancing light absorption efficiency,improving the separation and transfer efficiency of photogenerated carriers,and optimizing the efficiency of surface catalytic reactions,this paper strategically leverages the advantages of porous organosilica skeleton materials and inorganic semiconductors.Optimizing the composition and structure of catalytic materials through novel structural design,interface functionalization control and size control of functional units,a series of photocatalytic nanoreactors were successfully constructed,and the internal relationship between the interfacial properties of the materials,photogenerated charge behavior and photocatalytic aqueous-organic reaction performance has been systematically investigated.The outlined research contents are as follows:1.A porphyrin organosilane precursor（POP）was designed.Subsequently,a porous nanoreactor TiO₂@Por was constructed by coupling hollow TiO₂ nanospheres with porphyrins mesoporous organosilicon via the sol-gel method.Under green conditions,the TiO₂@Por showed exceptional photocatalytic activity for the oxidation of methylphenyl sulfide in an aqueous solution,achieving a remarkable yield of 98.9%with a selectivity of 99%,surpassing results from a single-group scenario.It has been demonstrated that the design of composite structures using multi-component synergistic interactions can enhance the light absorption ability and separation of photogenerated charges.The material’s unique pore structure,high specific surface area,and amphiphilicity effectively enrich hydrophobic organic substrates in the water while providing more reactive active sites and light absorption channels,improving the surface catalytic reaction efficiency of the material.This work explores the relationship between pore structure,pore wall composition,interfacial structure and surface properties of multiphase interfacial catalytic materials and their reactivity.It provides new insights for designing efficient interfacial photocatalysts.2.To further improve the separation ability of the photogenerated charge of the catalyst,a silanated cobalt porphyrin monomer（SCPM）was designed and synthesized,and HTNTCP nanoreactors with cobalt porphyrin mesoporous organosilicon（CPMO）and TiO₂ nanotube（HTNT）composite were further prepared.The unique porous double shell structure of the material facilitates exposure to more active sites.Additionally,the migration of photogenerated charge carriers along the nanotube’s length helps reduce the recombination rate.In the green catalytic system,the conversion rate of the HTNTCP photocatalytic oxidation of styrene was 99%,and the selectivity of benzaldehyde was 94%.These values were 3.8 times and 2.8 times higher than the single-component HTNT and CPMO,respectively.The enhanced catalytic performance can be attributed to two primary factors.Firstly,HTNTCP possesses a unique pore structure,high specific surface area and amphibiality,facilitating substrate adsorption and mass transfer.Secondly,constructing CPMO and HTNT heterostructures can significantly improve the separation efficiency of photogenerated carriers.Additionally,the metal-ligand charge transfer（MLCT）effect in cobalt porphyrins induces the directional transfer of photoelectrons from metals to porphyrins,further improving the performance of the composite photocatalyst.This study suggests a new approach to controlling the performance of interfacial catalysts.3.The optical absorption and photogenerated charge separation ability of the materials could be enhanced by designing the functional domain structure to regulate the functionalization of the interface and the size of the functional unit.Hence,a novel DPMSTNC nanoreactor was prepared by encapsulating Cd S QDs/TiO₂ heterojunction nanoparticles in dendritic porphyrin-based mesoporous organosilicon nanospheres（DPMSN）pores via a host-guest assembly strategy.Strong interfacial interactions between the guest materials,TiO₂ nanoparticles and Cd S QDs can improve the separation and transfer of photogenerated carriers.The DPMSTNC showed excellent catalytic performance in styrene oxidation,achieving 96%yield and 92%selectivity under mild conditions,higher than single component and simple composite catalysts.The results indicate that DPMSN with a dendritic structure serves as a platform for integrating Cd S QDs/TiO₂ nanoparticles and provides more light scattering and light tunneling effects for improved light absorption and light harvesting.The cobalt porphyrins dispersed throughout the skeleton of the main material can cooperate with the guest materials to enhance the photocatalytic performance.The guest molecules’assembly can be controlled by regulating the pore structure of the main material DPMSN.This study presents a novel approach to designing effective nanoscale photocatalysts.