Surface Modification Of TiO₂ Photocatalysts With Faceted Engineering For Photocatalytic Hydrogen Production

Photocatalytic hydrogen production technology as an effective solution to the energy and environment crisis.However,the application of photocatalytic technology in industrialization still faces many challenges.One of most reason is the low efficiency of solar-hydrogen conversion restricting the improvement of photocatalytic technology.In the process of photocatalytic hydrogen production,the higher photoelectron-hole compound rate restricts the improvement of photocatalytic efficiency.Therefore,it is necessary to modify TiO₂ nanophotocatalysts to improve the performance of photocatalytic hydrogen evolution.Due to the difference of coordination structure and surface potential energy,the semiconductor crystal planes show certain properties in the catalytic process,which has a significant influence on the photocatalytic efficiency.It is of great significance to study the effects of crystal surface on photocatalyst regulation and hydrogen production as well as the process of photocharge excitation,separation and conduction.Based on TiO₂ nanomaterials exposed to specific crystal surfaces as carriers,this paper explored the effects of crystal surfaces on organic matter pyrolysis,noble metal load and defect regulation and discussed its application in photocatalytic hydrogen production.Carbon hybridization can not only endow the visible light response of TiO₂,but also enhance the interfacial separation of charge carriers.Especially,the in-situ pyrolysis of organic polymers is one of the effective methods for carbon load.However,this process is closely related to the surface structure of the materials.Studying the effect of dicyandiamide pyrolysis on faceted-TiO₂ is of great significance for the design and construction of highly efficient photocatalyst.Based on anatase TiO₂ with{001}and{101}crystal facets exposed as the substrate,the effect of the crystal facets on the decomposition of the polymer and its application in photocatalytic hydrogen production were explored.This study shows that the{001}facet TiO₂ with the high potential energy carbonizes dicyandiamide,forming carbon dots on the surface of the nanosheet TiO₂.While{101}facet with low potential energy,dicyandiamide is deeply oxidized to form oxygen vacancies on TiO₂.The formation of oxygen vacancies promotes the separation of photo-generated charges.The photocatalytic hydrogen production rate of 30%dicyandiamide pyrolysis on{101}-TiO₂ is 8 times higher than that of pure{101}-TiO₂.Surface plasmon resonance of Au particles can effectively improve the optical response range of materials.Using noble metal Au co-catalytic supported on the surface of the TiO₂ with{001}facet exposed to explore the effect of defect TiO₂ with the surface reconstruction process regulated the charge behavior and the synergistic effect of plasma resonance and the defects was further understood,which can improve photocatalytic efficiency.This study shows that Au loading on the{001}-TiO₂achieves surface reconstruction,and the synergistic effect of plasmon resonance effect and defects makes the photocatalytic hydrogen production efficiency greatly reached2.78 mmol·h^-1·g^-1.Compared with nonreconstruction and traditional Au/TiO₂photocatalysts,the photocatalytic rate has been improved by 2 times and 3 times respectively.The bimetal co-catalyst can not only provide the active sites needed for the reaction,but also effectively reduce the reaction barrier.The Schottky junction between metal and the semiconductor promotes the separation of photogenerated charges,which has the effect of improving the efficiency of the photocatalytic reaction.Using anatase faceted-TiO₂ mainly exposed to{001}and{101}crystal facets as a substrate,study the synergy between faceted-TiO₂ and Au-Pt noble metal co-catalytic for efficiency photocatalytic performance.This study shows that the Au-Pt bimetal co-catalyst has a higher photocatalytic activity compared to the single noble metal Au and Pt supported samples.Especially,the average photocatalytic rate in 3 hours of Au-Pt bimetallic cocatalysts supported on{101}-TiO₂ achieves 27.21 mmol·h^-1·g^-1,while Au and Pt monometallic cocatalysts 4.57 and 6.95 mmol·h^-1·g^-1,respectively.