Study On The Controllable Construction And Hydrogen Evolution Properties Of BPEA-based Composite Photocatalyst

With the progress of science and technology,semiconductor photocatalysis has been recognized as one of the most effective strategies for solving energy shortage and environmental pollution problems since it is able to directly convert solar energy（low-density）to chemical energy（high-density）.As a traditional conjugated organic small molecule semiconductor,9,10-Bis（phenylethynyl）anthracene（BPEA）is considered as a promising optoelectronic functional material due to its strong absorption in the visible region and good crystallinity.Here in,we used BPEA as the main body and the effective dissociation of BPEA photogenerated excitons by constructing heterojunctions with other semiconductors to improve the separation of photogenerated changes and applied it to photocatalytic hydrogen evolution.Based on the effective construction and the mechanistic investigation of the photocatalytic hydrogen evolution process for the prepared heterojunction composites,the main research content of this paper was summarized in the following two aspects:（1）Focusing on the science problem of difficult separation of photo-excitons from BPEA conjugated organic nanocrystals,a novel type BPEA/CN heterojunction photocatalyst was synthesized by in-situ electrostatic self-assembly for the first time（CN is graphitic-phase carbon nitride）.Owing to the strong electrostatic attraction andπ-πinteractions between the heterojunction components,the hydrogen evolution activity of BPEA/CN photocatalysts was dramatically improved.Combined with the obtained series characterization results,the novel heterojunction mechanism of BPEA/CN photocatalyst was hypothesized.The extended photogenerated exciton lifetime in the new hybrid state and the improved photogenerated carrier separation efficiency between the heterojunction components work synergistically to achieve the excellent photocatalytic hydrogen evolution activity of this new type heterojunction material under the visible light region（λ>420 nm）.（2）To improve the general application of BPEA conjugated organic nanocrystals in the field of photocatalytic hydrogen evolution,the BPEA/Ti O₂ nanocomposite photocatalysts were successfully synthesized by effectively loading BPEA nanocrystals onto the surface of inorganic semiconductor titanium dioxide（Ti O₂）through a re-precipitation strategy.Compared with pure Ti O₂,BPEA/Ti O₂ nano-heterojunction has higher solar light utilization and stronger separation efficiency of photogenerated carriers.After loading BPEA nanoparticles onto nano-porous Ti O₂ semiconductor（M-T）,the obtained BPEA/M-T photocatalyst achieved its efficient hydrogen evolution under simulated sunlight without any metal co-catalyst.Moreover,under the visible light,the large number of photogenerated electrons generated by the photogenerated exciton dissociation of BPEA,which were successfully captured by Ti O₂,making the hydrogen evolution activity of the BPEA/M-T much higher than that of conventional CN organic semiconductor materials.