Study On Ⅰ-doped TiO₂ Nanotube Arrays For Planar Photocatalytic/photoelectrocatalytic Fuel Cell

With the continuous advancement of modernization,the pollution of ecological environment has become more and more serious,which has caused a bad impact on people’s production and life.The onstruction of ecological environmental protection is becoming more and more important in China,and a lot of research has been invested in the prevention and monitoring of water pollution.Pollutants can be degraded by semiconductor material-based photocatalytic or photoelectrocatalytic fuel cells in water,and the chemical energy can be recovered at the same time.The method has a good prospect in solving water pollution.TiO₂ Nanotubes Arrays（TNA）electrodes were prepared by anodic oxidation.The effects of different preparation processes on the catalytic degradation of Methylene blue（MB）was investigated by using TNA,and the optimized method for preparing TNA electrodes was obtained.I-doped TiO₂ Nanotubes Arrays（ITNA）electrodes were prepared,and ITNA was characterized using FESEM,XRD,XPS,and EDS,which proved that I was successfully doped into TNA.It was confirmed that the ITNA performance was the best for 2 h of electrolysis through the degradation of MB.The maximum photocurrent was 1.1 mA cm^-2,and the PL spectrum showed the lowest emission intensity,indicating that I doping in the ITNA electrode could increase the e^--h⁺separation rate;The UV-Vis spectrum showed that I-doping could significantly reduce the band gap width of TNA and enhance the absorption of visible light.Focusing on the structures,a planar photocatalytic fuel cell（p-PFC）was constructed using the prepared ITNA electrode.The experiment was compared the degradation of MB by p-PFC and traditional face-to-face photocatalytic fuel cell（f-PFC）,which proved that p-PFC had a higher degradation efficiency.The design of the planar structure could greatly increase the specific surface area of the cell and enhance the transmission of light and mass.Factors affecting the performance of p-PFC were explored,and it was confirmed that the degradation of organics would be influenced by cathode-anode distance,MB concentration and electrolyte types.The Langmuir-Hinshelwood（L-H）kinetic model was used to analyze the mechanism of MB degradation by p-PFC.It was shown that the degradation of MB mainly occured on the surface of ITNA electrodes in p-PFC,which was a rate-limiting step,and h⁺and·OH played a leading role in the degradation of MB.Based on the planar structure,the prepared ITNA electrode was used to explore the performance and influencing factors of Planar Photoelectrocatalytic（p-PEC）.The comparison between p-PEC and p-PFC proved that under the same conditions,the degradation rate of RhB by p-PEC was faster,which proved that the application of bias could accelerate the separation of e^--h⁺pairs.In p-PEC,the degradation performance was the best when the concentration of Na₂SO₄ was 10 mmol L^-1,the RhB concentration was 10 mg L^-1,and the bias voltage was 1.2 V.The L-H kinetic model was used to explore the mechanism of p-PEC degradation of RhB.It was proved that the degradation of RhB in p-PEC mainly occurred on the electrode surface,which belonged to the interface-catalyzed degradation reaction.h⁺and·OH particles played the main roles in degradation of RhB.