Based On The Semiconductor Materials For Modification And Photocatalysis Research

Solar energy driven water splitting into hydrogen has been considered as one of the major strategies to provide clean energy.metal oxide semiconductors as photocatalyst for water splitting have attracted extensive research.In this article,we mainly study and discuss the modification methods to improve the photocatalytic activity of semiconductor in terms of constructing the organic-inorganic heterojunction and doping.We explore the way to improve catalytic activity,respectively based on two kinds of TiO₂ and Co3O4 catalyst systems for experiments and characterization,details are as follows:（1）Photocatalytic H₂ evolution activity of the TiO₂@COP-64 composites:we prepared a series of TiO₂@COP-64 hybrids by Yamamoto reaction and hydrothermal method.The as-prepared TiO₂@COP-64 hybrids was characterized by XRD、TEM、HRTEM、UV-vis、BET and so on.The photocatalytic activity of TiO₂@COP-64 composites for splitting water into H₂ was detected under solar light.TiO₂@COP-64 hybrids show remarkably stability and activity for H₂ production.Particularly,the corresponding hydrogen production rate of the hybrids reached 15.02 mmol h-1 g-1,which exceed 63%comparing with that of pristine TiO₂ nanosheets（9.20 mmol h-1 g-1）.（2）Photocatalytic hydrogen production mechanism of the TiO₂@COP-64 hybrid:after characterizing the prepared samples by CV and fluorescence lifetime,we proposed that the interaction between TiO₂ nanosheets and COP-64 provided a charge transfer channels and favored the electron transfer from conduction band of COP-64 to that of TiO₂ and the hole transfer from the valence band of TiO₂ to that of COP-64,which inhibited greatly the combination of photogenerated e-and h+ in the hybrid system.（3）Photocatalytic H₂ evolution activity of the La_xCo_3-xO₄/G composites:non-noble metal La_xCo_3-xO₄ solid solution based on graphene(La_xCo_3-xO₄/G)photocatalist were prepared by the microwave hydrothermal and in-situ chemical deposition methods.The as-prepared La_xCo_3-xO₄/G hybrids was characterized by XRD、TEM、HRTEM、XPS、PL and so on.The nanohybrid photocatalyst sensitized by Eosin Y exhibited activity for hydrogen generation 2-fold higher than Co3O4/G under visible light irradiation.The highest H₂ evolution of nanohybrid reached 6.543 mmol h-1 g-1 when the molar ratio of La/Co is 10%in the nanohybrid.（4）Photocatalytic H₂ evolution process of the La_xCo_3-xO₄/G hybrid:the prepared samples were characterized by MS,fluorescence lifetime,transient absorption spectra and transient absorption kinetics of curve,the results showed that the particle growth of nanohybrid could be confined after modifying Co3O4 by La,the lattice defects could be formed,and also changed the band structure to eventually improve the photocatalytic activity.The electron transfer process of photocatalytic hydrogen production was introduced in detail in the next articles.