Preparation And Study Of Dibenzothiophene Sulfone Based Conjugated Polymer For Hydrogen Production Under Visible Light Irradiation

The increasing energy demand has led to the shift of the focus from the development limited non-renewable resources(petroleum products,natural gas,etc.)to the green natural fuels.Hydrogen is an ideal energy carrier because of its high energy density and less pollutants.In addition,one hour of solar energy can meet the energy consumption of the world in one year.Therefore,using photocatalyst to generate clean hydrogen through photoelectrochemical reaction is the most promising technology to overcome the energy crisis.Conjugated organic polymers,which are composed of abundant carbon and nitrogen stored in the earth,have been widely studied in recent years because of their low cost,high porosity and stable hydrogen production performance.At the same time,their energy band position and band gap width can meet the requirements of hydrogen production under visible light irradiation through reasonable construction of functional group in conjugated polymers.In this project,a series of dibromodibenzothiophene sulfone-based polymers are prepared through coupling reaction.And their optical properties can be tuned by reasonable design and molecular engineering,thus their light absorption performance and hydrogen production efficiency of the dibromodibenzothiophene sulfone-based polymers can be improved.The main research contents are as follows:(1)Using 1,3,5-triacetylenebenzene and 3,7-dibromodibenzothiophene sulfone as raction monomers,their conjugated copolymers were prepared by palladium salt-catalyzed coupling method.Interestingly,a small amount of 1,3,6,8-tetrabromopyrene is introduce into the polymerization system,the photocatalytic activity can be tuned.Various characterization methods were used to confirm the successful doping of the pyrene ring into the copolymer.At the same time,with a proper amount of pyrene ring doping,the absorb visible light ability,the transmission rate of carriers,and the activity of the combination of photogenerated electrons and hydrogen ions of the copolymers can be improved.Thus,their hydrogen production performance has been significantly improved.When the molar ratio of doped pyrene to thiophene sulfone is 1:100,the hydrogen production efficiency of the pyrene doped copolymer reaches to the maximum value,and its hydrogen production rate is about 15 times than that of undoped copolymer.(2)Using 3,7-dibromodibenzothiophene sulfone and 1,3,6,8-tetrabromopyrene as raw materials,their conjugated copolymers were obtained by Yamamoto coupling method.The ratio of electron withdrawing groups to electron donating groups in the polymer can be tuned by changing the ratio of two monomers.The successful polymerization of two monomers was proved by various characterization methods.At the same time,when the ratio of the two monomers is an appropriate value,the visible light absorption capacity,the carrier transmission rate,the activity of the combination of photo-generated electrons and hydrogen ions,and the hydrogen production performance of the copolymers are significantly improved.When the ratio of thiophene sulfone to tetrabromopyrene is 3:2,the hydrogen production performance reaches 6849μmol g-1 h-1.