| This work presents TiO2 nanotube arrays electrode loaded with Zn nanoparticles by chronoamperometry method. First, TiO2 nanotubes electrode was prepared by anodization. Secondly, the voltage of Zn2+ reducing to Zn on TiO2 nanotubes was tested by cyclic voltammetry. Finally, Zn was deposited onto TiO2 nanotubes by chronoamperometry method. The morphology and size of Zn nanoparticle loaded on TiO2 nanotubes electrode was easily controlled by chronoamperometry deposition time and voltage.The deposition parameters including cathode voltage, deposition time, electrolyte concentration and adding support electrolyte (KCl) were investigated. Acording to SEM and chronoamperometry real time recording analysis results, under the same deposition condition, increasing voltage from -1.25V to -2V, the content of metal Zn increased and particle size of metal Zn enlarged. When the deposition voltage was improved to -2V, Zn formed hexagonal structure in a preferred orientation. Prolonging deposition time from 3s to 10s, Zn nanoparticles had a diameter of about 15nm ~ 1um. Increasing electrolyte concentration, the content of Zn increased. Adding support electrolyte KCl, the content of Zn increased, particle size of Zn enlarged and formed hexagonal structure. Finally, The XRD anlysis showed that we successfully loaded Zn onto TiO2 nanotube arrays electrode. The crystal diameter of Zn nanoparticles is about 0.82nm.The experiment studied the photoelectricity character of Zn-TiO2 nanotube composite electrodes before and after loaded with Zn for different deposition time. The UV–vis diffuse reflectance spectra found that Zn loaded sample extended red shift and enhanced absorbance in the range of 487–780nm. The peak position experienced a red shift from 400nm,455nm,600nm to 420nm,505nm,663nm. Flat-band potential of Zn-TiO2 composite electrode for deposition 5s was negativest, about -1.9203V. Carrier concentration of Zn-TiO2 composite electrode for deposition 3s was highest, about 14.14692887×1020 cm-3. For the influence of flat-band potential and carrier concentration on photocurrent, the photocurrent response of Zn-TiO2 composite electrode for deposition 5s was the strongest, about 3.80×10-5 A.The photoelectrocatalysis degradation of methylene blue was carried out using TiO2 nanotube electrode and Zn-TiO2 composite electrode of different deposition time. Zn loaded TiO2 nanotube can enhance the photoelectrocatalysis efficiency and there is the best deposition time. We found the photoelectrocatalysis efficiency of Zn-TiO2 composite electrode for deposition 5s was highest, which was about 86.2% under 0.6V bias potential for 14hrs. On the one hand, flat-band potential of Zn loaded sample shifted to negative leading to enhance the fermi level and decrease energy-band width of TiO2 nanotube. Zn-TiO2 composite electrode harvests light more effectively and can produce more photogenerated electrons and holes than the unloaded sample. On the other hand, Zn-TiO2 composite electrode improves the carrier concentration to enhance photoelectrocatalysis efficiency.The photoeleetrocatalytic degradation of methylene blue by Zn-TiO2 composite electrode at deffirent bias potential was investigated.The results found that bias potential was the bigger and photoelectrocatalysis efficiency the higher. Bias potential is helpful to produce photogenerated electrons and holes and retard the recombination of photogenerated electrons and holes to increace the reaction opportunity of holes and methylene blue. We found Zn-TiO2 composite electrode was rather stable and could be used repeatedly.
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