The Application Of Metal Modified TiO₂ Nanotube Arrays On Photoelectrocatalytic Reduction Of Cr???

As the highly effective photocatalyst,TiO₂ nanotube arrays are often used in the photocatalytic and photoelectrocatalytic field because of their special surface structure.TiO₂nanotube arrays are applied in the photocatalytic and photoelectrocatalytic field for removing heavy metal and the hard degradation contamination,which could not result in secondary pollution easily.TiO₂ nanotube arrays have become the research hotspot of widely scholars.In this paper,highly ordered TiO₂ nanotube arrays were prepared by anodic oxidation.Through the comparison of TiO₂ nanotube arrays prepared in aqueous system and organic system of ethylene glycol,TiO₂ nanotubes grown organic system has better photoelectric properties and photocatalytic activity.On the basis of TiO₂ nanotubes prepared in organic system,Cu particles were loaded on TiO₂ nanotube surface by impregnation-reduction method.Cu/TiO₂ NTs had the best photoelectric properties and loading content when the concentration of CuSO₄ solution was 0.01 mol L^-1.The photocurrent density was 0.66 mA cm^-2 which was 1.7 times of unmodified TiO₂ NTs under 2.0 V bias?vs SCE?.The highest photoconversion efficiency was 7.42%.The removal of Cr???was fastest in photocatalytic reduction process which reached 78%under the condition of pH=2.5 and Cr???initial concentration of 20 mg L^-1 for 40 min.Secondly,Ni/TiO₂ NTs were prepared by electrochemical deposition method.The optimum preparation conditions were that the deposition potential was-1.5V,the deposition time was 60s,the concentration of NiSO₄ was0.05 mol L^-1.Ni/TiO₂ NTs prepared at optimum conditions has the highest photocurrent density of 1.04 mA cm^-2 which was 2.7 times of unmodified TiO₂ NTs.The highest photoconversion efficiency was 13.05%.In the electrochemical?EC?process,the direct photolysis?DP?,the photocatalytic?PC?process and the photoelectrocatalytic?PEC?process,the removal of Cr???in the PEC process was 58.3%under the condition of pH=2.5 and Cr???initial concentration of 20 mg L^-1.The removal of Cr???in the PEC process was higher than the summation of the PC and EC processes acting alone,implying that there was cooperative interaction between photocatalytic and electrocatalytic process.At last,the photocatalytic fuel cell was built in which the Ni/TiO₂ NTs and Pt electrode were used as the light anode and the cathode.Photocatalytic reduction of Cr???was performed in PFC.The removal of Cr???was 47.1%under the condition of pH=2.56.The results indicate that PFC can promote photogenerated electron and hole effective separation.