Synthesis Of Covalent Triazine Framework Composite Materials And Prussian Blue Derived Materials And Their Photocatalytic Hydrogen Evolution Performance Study

Energy crisis has always been one of the challenges without solution.With the deplete of fossil fuels,new energy will gradually replace its dominant position.In the 21st century,,hydrogen energy is considered to be the most promising energy for fossil fuels.Compared with using the secondary electric energy,the photocatalytic hydrogen production by water splitting can directly transform the renewable solar energy.This concise process allows solar energy to be more competitive economically.The design of efficient photocatalysts plays a crucial role for overcoming a large energy barrier in photocatalytic HER.As one of the Covalent Organic Frameworks（COFs）materials,Covalent Triazine Frameworks（CTFs）has strong stability and has been widely used for photocatalytic hydrogen production in recent years.Among them,CTF-1 formed by condensation of terephthalonitrile has a well layered structure,π-conjugated aromatic ring and triazine ring,which can be well combined with other materials.As a kind of coordination compounds,Prussian Blue Analogues（PBAs）have good electrical conductivity and metal regulatory properties,and have been widely used in various fields.However,its application for photocatalytic hydrogen evolution is rarely reported.This work mainly includes the following two parts:（1）Pt nanoparticles（NPs）as active species have always been one of the best candidates for semiconductor materials in photocatalytic hydrogen evolution.A schottky heterojunction has been constructed in term of loading the Pt NPs onto a triazine-based framework evenly in order to maintain the high activity of these ultra-small Pt NPs and maximize the utilization of Pt.This kind of composite reached a high hydrogen evolution rate of 20.0 mmol g^-1h^-1（AQE=7.5%,atλ=420 nm）with the 0.40 wt%Pt content,which gives a 44-fold-enhanced efficiency for photocatalytic hydrogen production comparing to the unmodified CTF-1.According to the result of density functional theory（DFT）calculation,the strong electron transfer（Q（Pt）=-0.726 q_e）between Pt NPs and CTF-1 trigger a strong interaction,which makes Pt NPs being sticked firmly to CTF-1,giving the composite very good stability and excellent cyclic hydrogen production capacity.TheΔG_H*of Pt@CTF-1 is less than CTF-1,which may be the source of the significant improvement of photocatalytic performance.Our work thereby suggests a new approach to combine of NPs with COFs for highly efficient photocatalysts.（2）Considering the high cost of precious metal materials,the Lego-like PBA-Mo S₂photocatalysts without precious metal were prepared by Ni-Co PBA as matrix material.There is a small amount of in-situ generated Mo S₂on PBA by etching method.The PBA-Mo S₂composite has fascinating performance for photocatalytic hydrogen production,which is higher than some noble metal composite catalysts with the hydrogen production rate of 22.69 mmol g^-1h^-1.The surface area of PBA is increased through etching,and the catalytic active sites of PBA-Mo S₂-10 are fully exposed,which can greatly boost the photocatalytic hydrogen evolution performance.The combination between Ni-Co PBA and Mo S₂reduces the band gap,promotes the transfer of photoelectrons,and accelerates the photocatalytic reaction.These advantages may be the cause of high photocatalytic performance.This strategy provides a new scheme for the incentive of high efficiency photocatalyst.