Research On Surface Modification And Properties Of 2D-TiO₂(B) Materials

Rapid industrial development and population growth have sparked a global crisis concerning the energy shortage.It is now an urgent task to develop green and sustainable materials used in clean energy production and environmental remediation for the purpose of the long-term development of human society.In recent years,2D nanosheet materials have attracted extensive attention in the fields of photocatalytic hydrogen production and electrochemical energy storage due to the structural advantages,such as large specific surface area,more active sites and good electron mobility.In this dissertation,we synthesized 2D-TiO₂(B)as the basic material and modified the surface structure by using plasma engraving technique and electrostatic adsorption method.By optimizing the synthesis scheme and controlling the reaction variables,this modified 2D-TiO₂(B)would help us to obtain the material with superior performance for photocatalytic and energy storage.This research lays a foundation for developing and realizing the wide application of multi-functional clean energy materials by enhancing the catalytic activity and conductivity of traditional TiO₂ materials.(1)The plasma engraving treatment is an effective method to improve the photocatalytic performance of TiO₂(B)nanosheets.The plasma treated TiO₂(B)with defects Ti³⁺and O vacancy performed advantages over pristine TiO₂(B)nanosheets in production of H₂ under full spectrum light.The inserted defect state below the conduction band shortened the width of original band gap and significantly extended the optical absorption spectrum of TiO₂(B)to the visible light region.The engraving effect of plasma generated porous structure on pristine TiO₂(B)nanosheets and increased specific surface area apparently.The exposed surface area with more active sites would facilitate the dissociative adsorption of the reactant molecule and promote the reaction efficiency.(2)To improve the electron transport efficiency of engraving TiO₂(B),the TiO₂(B)/graphene composites(TGN)have been synthesized by using the hydrothermal method.After plasma engraving treatment with TGN(PTGN),the PTGN material have obtained and exhibited a better performance of photocatalytic hydrogen production and photocurrent density compared with the original TGN materials.The modified PTGN materials exhibited higher specific surface area and more high-energy active sites for surface photocatalytic reaction.Moreover,the graphene conductive layer could provide a special channel for the transmission of photogenerated electrons in PTGN,which not only accelerated the rate of electron migration,but also inhibited the recombination of electrons and holes in the material.Especially,introducing the graphene as well as intrinsic defect(oxygen vacancy and doping Ti³⁺)in TiO₂(B)could optimize energy band structure of TiO₂(B)though broadening the spectral absorption range,thus separating the electrons and holes and improving the photocatalytic reaction efficiency.(3)Due to the superior electronic mobility of PTGN materials,the research is based on the PTGN composite materials with different plasma engraving time for the study of supercapacitor property.Surface etching defects of V_O and Ti³⁺greatly improved the rating of ionic charge.The PTGN material with 30 min(P30)engraving processing exhibited the best performance among these three electrode systems.The specific capacitance of P30 sample reached 232.3 F/g under current density of 0.25A/g and the charge-discharge cycle test(5000 laps,4 A/g)maintained 88.3%,which showed a high capacitance retention rate and excellent cycle stability.(4)To simplify the synthesis process and improve the surface catalytic activity of the TiO₂(B),the metal ammonia complex was stably anchored on the surface of TiO₂(B)by means of the electrostatic adsorption method for promoting photocatalytic efficiency of hydrogen production.The resulting of Co(III)NC-TiO₂(B)exhibited a highly stable photocatalytic H₂ evolution rate.The H₂ evolution of metal complexes can be achieved through dehydrogenation of the surface amino.The facile method of electrostatic adsorption could well absorb with the transition metal ammonia complex(TMAC)onto TiO₂(B)surface,such as Co(III)NC,Ni(II)NC and Cu(II)NO.The superior photocatalytic H₂ evolution was originated from the strong electrostatic adsorption between metal complex and TiO₂(B),which could lead to the efficient migrating of charge and separating of electrons-holes.This research provides a basis for the H₂ production from non-noble metal complexes in the future.