Preparation Of Photocatalytic Fuel Cell Based On BiVO₄/TiO₂ NT And Cu₂O/TiO₂ NT And Its Performance

Water pollution has become the focus of current environmental control.However,traditional water treatment methods have many problems,such as high energy consumption,incomplete treatment,etc.Moreover,traditional water treatment methods are difficult to utilize chemical energy in wastewater,resulting in waste of resources.Therefore,it is of great significance to develop an efficient water pollution degradation process and realize the recycling of energy.Microbial fuel cell?MFC?is a widely reported waste water recycling technology,but it cannot be applied on a large scale due to low degradation efficiency,complex process and difficulty in degrading macromolecular toxic pollutants.Based on the principle of Fermi level matching,the photocatalysis fuel cell?PFC?with dual photoresponsive electrodes has been fabricated.Firstly,the titanium dioxide nanotube array?TiO₂ NT?was prepared by anodic oxidation method.Then,narrow band gap n-type semiconductor BiVO₄ was electrodeposited on it and served as photoanode.Electrodepositing p-type semiconductor Cu₂O responding to visible light utilized as photocathode.The BiVO₄/TiO₂ NT-Cu₂O/TiO₂ NT dual-photoelectrode PFC system was successfully constructed for chemical energy recovery and organic matter degradation.Specific results were as follows:BiVO₄/TiO₂ NT photoanode and Cu₂O/TiO₂ NT photocathode were both prepared on the TiO₂ NT with three-dimensional array structure,BiVO₄ and Cu₂O were loaded on it by electrodeposition.BiVO₄/TiO₂ NT and Cu₂O/TiO₂ NT materials with different proportions were prepared by adjusting the deposition voltage and deposition time in the deposition experiment.The morphology,composition and light absorption of photoelectrode materials were characterized by SEM,XRD,XPS and UV-vis DRS.Photoelectricchemical performance of electrodes were evaluated by photocurrent density,open circuit potential,EIS,Mott-Schottky curve and other testing methods.Finally,the photoanode and photocathode materials with the best photoelectric response were obtained.BiVO₄/TiO₂ NT-Cu₂O/TiO₂ NT dual-electrode PFC was constructed.Under the conditions of simulated sunlight irradiation and external 1?resistance,phenol compounds4-chlorophenol?4-CP?,antibiotics norfloxacin?NOR?and tetracycline hydrochloride?TCH?were taken as target pollutants,and 0.1 mol/L Na₂SO₄ was added to increase the conductivity of the solution,so as to carry out photocatalytic degradation and electricity generation research on the system.The results showed that the reaction kinetic constants of 4-CP degradation were 1.21 and 2.26 times higher than that of BiVO₄/TiO₂ NT-Pt single electrode PFC and Pt-Cu₂O/TiO₂ NT single electrode PFC respectively.The kinetics constant of NOR degradation was 1.72 and 1.40 times greater than that of other two kinds of single-electrode PFCs;The kinetic constant of TCH degradation was 1.04 and 2.57 times greater than that of other two kinds of single-electrode PFCs.At the same time,the polarization curves of photocatalytic fuel cell system in three pollutants were tested.The results showed that the maximum power density of dual-electrode PFC in three pollutants was 1.23,1.49 times and1.68 times higher than that of BiVO₄/TiO₂ NT-Pt single electrode PFC respectively,was 3.56,5.57 and 6.66 times higher than that of Pt-Cu₂O/TiO₂ NT single electrode PFC.The dual-electrode PFC designed in this study has been proved to have good stability through multiple degradation experiments of TCH.Analysis reason:under the irradiation of simulated sunlight?wavelength:420-800 nm?,the flat band potential of BiVO₄/TiO₂ NT photoanode was higher than that of Cu₂O/TiO₂ NT photocathode.The potential difference spontaneously drived the photo-generated electrons of the photoanode transfer to the photocathode through the external circuit,avoiding recombination with self holes and forming the external circuit current.Highly oxidizing holes releasing on the photoanode and highly reducing electrons left on the photocathode can directly degrade pollutants.The research provides a new solution for water pollution treatment and energy recovery.