Studies Of Polymeric Conjugated Semiconductor Photocatalysts And Anchored Single-atom Catalysts

The growing consumption of fossil energy and the resulting environmental pollution problems urge us to develop new technologies for utilizing alternative clean renewable energy sources.Converting solar energy into chemical energy through photocatalysts is one of the most promising ways of solar energy conversion and utilization.However,traditional oxide semiconductors are only responsible for ultraviolet light（about 5%of the solar spectral energy）due to the wide-bandgap.Visible light（400-760 nm）as a major component of the solar spectrum offers a large amount of energy of the solar irradiation.Polymer conjugate semiconductor has attracted great attention for its unique advantages such as wide visible light absorption range,high light absorption coefficient,and easy molecular tailoring.Despite these advantages,different polymer conjugate semiconductors still suffer from low charge separation efficiency,low charge transfer rate,and limited optical absorption range.In this paper,methods like copolymeric strategy,defect engineering,molecular modification,and single-atom cocatalyst anchoring are employed to improve the performance of polymeric photocatalysts.This study may open a new door for novel polymeric photocatalysts exploring.The specific content and results are as follows:1.Pristine g-C₃N₄ suffers from limited visible light absorption and inefficient charge separation.A copolymerization method is employed by using creatinine as the second monomer with urea for modified g-C₃N₄ synthesis.The synthesized copolymer exhibits extended visible light absorption（>550 nm）and enhances charge separation.The hydrogen produced by copolymer catalyzed reaction is 3 times larger than that of pristine g-C₃N₄.2.To further improve the optical absorption of polymeric photocatalysts,inactive polythiophene is investigated for its excellent absorption property.Different types of coupling,terminal groups,and short molecules are confirmed as structural defects.These structural defects affect light absorption and serve as active sites for photocatalysis.By rational design and consciously control,a high-performance core/shell compound polythiophene photocatalyst with up 650 nm light response was synthesized.3.To gain a deeper understanding the relationship between structure and performance,acyclic Diene metathesis（ADMET）and post-polymerization modification（PPM）were employed for the synthesis of method synthesis of poly（thienylene vinylene）s（PTVs）with extended side-chain cross-conjugation.The performance of the modified polymer was studied for both photovoltage and photocatalysis applications.In this study,we found installing strongly electron-withdrawing groups is an effective way to improve the performance of polymer,leading to lowed bandgap and quenched fluorescence.4.To study the effects of active sites for photocatalysis,0.1 wt.%Pd₁/C₃N₄ was synthesized and introduced for light-driven ethane oxidation.The selectivity of acetic acid reached up to 98.7%and a TOF of 262.2 Acetic acid per Pd site per hour.Regarding the amphiphilic properties and semiconductive electronic structure of g-C₃N₄,a novel strategy for anchoring high-density single metal atoms on polymeric semiconductor g-C₃N₄ was developed.A series of Pt single-atom catalysts with different Pt loading up to 6.0 wt.%was synthesized.Investigation light-driven water splitting for H₂production reaction,the catalyst with 3.0 wt.%single Pt atom loading performed the best catalytic activity.This method showed good generality for anchoring other transition metals such as Pd,Cu,Ni with high-density loading.