Synthesis Of Cu Doped TiO₂ Nanotubes And Their Photoelectric Properties

Organic pollutants have seriously affected the global environment and human health.The development of green degradation of organic pollutants has become the key to solving its pollution problems.Photocatalytic technology using solar energy to deal with environmental pollution has become the focus of researchers in recent years.As an n-type semiconductor material,TiO₂ nanomaterials have great application potential in the field of photocatalytic degradation of organic matter.However,the response range of TiO₂ nanomaterials to sunlight is limited to the ultraviolet region,which limits its practical application as a photocatalyst.In this paper,the first photochemical and thermodynamic analysis are used to predict the photochemical properties of different crystal forms,morphologies and doped structures,and the crystal forms,morphologies and doping structures with good photochemical properties are designed,which is used as follow-up experiments.guide.On the basis of the above theoretical design,the highly aligned and ordered anatase TiO₂nanotube structure is successfully prepared by two-step anodization.As a substrate of photocatalyst,a Cu-doped TiO₂ nanotube structure is prepared by a simple electrochemical deposition process,thereby expanding the visible light response range and intensity of the TiO₂ nanotube material and improving its photocatalytic activity.Scanning electron microscopy?SEM?,X-ray diffractometry?XRD?,high resolution electron projection microscopy?HRTEM?and X-ray photoelectron spectroscopy?XPS?are used to analyze the microstructure,phase composition,elemental composition and composition of the microstructure before and after doping.The valence distribution is characterized.The photoelectrochemical performance of the photocatalyst before and after doping is tested by UV-vis diffuse reflectance spectroscopy?UV-vis?,instantaneous photocurrent response curve and Nyquist curve.The photocatalytic activity of the material is verified by photocatalytic degradation of the organic pollutant rhodamine B.Finally,the catalytic mechanism was explored and the following conclusions were obtained.?1?Under static conditions of room temperature,the Cu-doped TiO₂ nanotubes with different concentrations are successfully prepared by simple electrodeposition process.The Cu atom replaces the position of the Ti atom,which does not change the microstructure and crystal structure of TiO₂,and exists in the form of Cu⁺ions.When the doping concentration is 0.25 mol/L,the response range of Cu⁺/TiO₂ nanotube structure to sunlight is extended to the light region?456 nm?,and the band gap width is reduced by 0.52 eV compared with the pure TiO₂ nanotube structure,which has a high visible light absorption efficiency.Under the irradiation of sunlight,the photo-generated carrier density of the Cu⁺/TiO₂ nanotube structure is increased by 165%compared with the pure TiO₂ nanotube,and the fluorescence intensity is significantly reduced.Cu⁺ion doping promotes the increase of photocarrier density,inhibits the photo-generated electron-hole pair recombination,and improves the degradation efficiency of organic pollutants RHB by 82.6%.The photocatalytic degradation mechanism is discussed.The improvement of photocatalytic performance of Cu⁺/TiO₂ nanotubes is attributed to the fact that the doping changs the energy level structure of TiO₂,improves the visible light response intensity and range,and reduces the forbidden band width.At the same time,Cu⁺acts as an electron acceptor,and undergoes a reduction reaction to form a strong oxidizing hydroxyl radical,which can be further combined with electrons.It promotes the transfer of photogenerated electrons and inhibits the recombination of electron-hole pairs,thereby increasing its photocatalytic activity.?2?The Cu⁺/TiO₂ nanotube structure,Cu₂O/TiO₂ nanotube semiconductor composite structure and Cu₂O/CuO/TiO₂ nanotube semiconductor composite structure are successfully prepared by changing the chemical environment of the micro-area in the electrochemical deposition process by different stirring methods?quiescent,magnetic stirring,ultrasonic vibration?.The results show that the different doped modified structures have not changed the anatase crystal form of TiO₂ nanotubes.The p-type semiconductors CuO₂ and CuO are supported on the surface of the TiO₂ nanotube wall,and form a semiconductor composite structure with the TiO₂ nanotubes as a novel photocatalyst material.The photocatalyst can further extend the optical response range to 503 nm.Under natural light,the photo-generated carrier density is further increased to 0.92 mA/cm²,and the optical properties are further optimized.At the same time,the charge transfer resistance of the semiconductor composite structure is reduced compared with the Cu⁺/TiO₂ nanotube structure,which is beneficial to the transfer transfer of photogenerated carriers.The degradation rate of RHB by photocatalyst increases to89.52×10^-3/min,which is 339%higher than that of Cu⁺/TiO₂ nanotube structure.The increase in photocatalytic activity is related to the energy level structure of the p-type semiconductor Cu₂O.Due to the difference between the Fermi levels,a built-in electric field is formed at the semiconductor interface under thermal equilibrium conditions.Under the premise of the reduction of charge transfer resistance,the built-in electric field further provides power for the transfer transmission of photogenerated electrons,which is beneficial to the photocatalytic reaction.