The Preparation Of Thiophene Modified Doubleshell Hollow G-C₃N₄ And The Construction Of Artificial Photosythesis System

Excessive carbon dioxide emissions are likely to lead to environmental pollution and global climate change.Compared with the inorganic catalytic CO₂ reduction,the artificial bio-photosynthesis system makes better use of the synergistic effect between the high photosensitivity of inorganic photocatalytic materials and the high efficiency and selectivity of enzyme catalysis.In this system,an important bottleneck limiting the photocatalytic efficiency is the photocatalytic regeneration efficiency of the redox-active coenzyme factor.Among the various semiconductive catalytic materials,C₃N₄ with the photocatalytic function,has attracted much attention due to its advantages of simple synthesis,high physical and chemical stability,excellent electronic band structure and biological compatibility,but C₃N₄ still has some defects such as low light absorption and low electron-hole pair separation efficiency intrinsically.In this study,for the first time,we constructed a thiophene ring modified doubleshell hollow g-C₃N₄ nanospheres（ATCN-DSCN）and applied it to the artificial photosynthetic system through the collaborative use of nanostructure and electronic band structure.We employed the doubleshell hollow Si O₂ spheres as the template to get the ATCN-DSCN.Through a series of characterization can get the morphology,crystal and chemical structure of ATCN-DSCN,and the spectra of UV-Vis DRS,PL and photocurrent response test illustrated that the incorporation of thiophene ring modified the electron band structure of C₃N₄,which greatly improved the light absorption and utilization ability,the electron-hole pair separation efficiency,and the electron transfer efficiency.The ATCN-DSCN material exhibited outstanding optical and photoelectrical properties,enabling a NADH yield of～74%,which was～40-folds higher than that of the bulk C₃N₄（～1.76%）.ATCN-DSCN enabled a turnover frequency（TOF）of 2.950hr^-1,which,to the best of our knowledge,is the highest record of the TOF for photo-regeneration of NADH.ATCN-DSCN photoreduced NAD⁺to NADH was further coupled with formic acid dehydrogenase（FDH）to achieve the sustainable of photo-reduced CO₂ to formic acid（HCOOH）.In this paper,the enzyme-assisted artificial bio-photosynthesis system effectively converted CO₂ into formic acid,resulting in a final yield of 290μM after 9 hours light illumination.