Ionothermal Synthesis And Photocatalytic Reduction Of CO₂ On Co@PdTCPP-MOFs And ZnFe₂O₄/FeP-CTFs

The CO₂accumulation of the atmosphere is the primary cause of global climate change in the modern.CO₂ capture and storage technology?CCS?is an effective method of reducing the concentration of atmospheric CO₂.However,a more economical and greener way is the efficient conversion of CO₂ to the valuable chemicals?such as CO and CH₄?by using solar energy.The absorption of solar energy by photocatalysts results in the generation of pairs of electrons and holes,which participate in reduction and oxidation,respectively.With different numbers of electrons transfer,CO₂ can produce a variety of reduction products in the reaction.The reaction pathway is determined by the bonding strength between CO₂ or the intermediate species and the active sites of the photocatalyst surface.The efficiency of CO₂reduction depends on he adsorption and activation of CO₂on the photocatalyst.As a new strategy,the ionothermal synthesis was adopted to enhance the CO₂adsorption capacity of the photocatalyst.In the process of reaction,the ionic liquid can be used as structure directing agent or catalyst,which is bale to get a catalyst with differet structes with those of hydrothermal and solvothermal.Therefore,this paper is focused on the adsorption behavior of CO₂and the preparation of different photocatalysts by the ionothermal method.The different kinds of ionic liquids?room-temperature ionic liquids and molten salts?are used in the paper,which are not only a solvent but also catalyst.The physical and chemical properties of the materials can be improved by the structural guidance of ionic liquids,such as the adsorption capacity and photoreduction properties of CO₂:?1?A metalloporphyrin-based Metal-Organic Frameworks?Co@Pd TCPP-MOF?was synthesized by two kinds of ionic liquids in the ionothermal condition.The catalyst was characterized by a series of methods,such as luminescence spectra,photocurrent response,etc.The results indicate that Co@Pd TCPP-MOF has good potential in photochemistry.Co@Pd TCPP-MOF shows a good adsorption capacity for CO₂ fixation at normal pressure by CO₂ adsorption experiments,which is beneficial for the subsequent reaction of CO₂ reduction.And it exhibits an excellent activity due to the high generation rate of CO(156?mol h^-1 g^-1)under visible light.The density functional theory calculations indicate that the CO₂adsoption capacity of MOFs can be enhance by the involvement of Pd-N₄ and Co?II?-O clusters.Moreover,the adsorption energy of CO₂ on the Pd-N₄ is similar to that of CO₂ on the Co?II?-O clusters.It means that CO₂ reduction reaction can simultaneously occur in the surface of Pd-N₄ and Co?II?-O clusters,and then produce more active-sites.?2?The Zn Fe₂O₄ nanoparticles decorated Fe-based Covalent Triazine Frameworks?Zn Fe₂O₄/Fe P-CTFs?was successfully synthesized by a facile one-pot ionothermal method.Due to the Fe-N₄ structure,Zn Fe₂O₄ nanoparticles can be grown in-situ on the surface of Fe P-CTFs in the ionic liquid.Zn Fe₂O₄/Fe P-CTFs was studied for photocatalytic reduction of CO₂ under visible light.It shows better performance than alone Zn Fe₂O₄ nanoparticles,Fe P-CTFs and their physical mixture,with a CO generation rate of 178?mol h^-1 g^-1.A high surface area of Zn Fe₂O₄/Fe P-CTFs results in the enhancement of CO₂ adsorption,the exposure of active sites and strong interaction between CO₂ and active sites.The density functional theory calculations and optical properties indicate that the strong interactions between Zn Fe₂O₄ and Fe P-CTFs can facilitate the transfer and separation of interfacial charges,and then enhance the excellent photocatalytic performance.