Study On The Performance Of Photocatalytic Fuel Cell With Organic-BiVO₄-Modified TiO₂ Photoanode

With the rapid development of industrialization and economy,mankind is facing two major problems:environmental pollution and energy crisis.In recent years,environmental pollution has become more and more serious.A large amount of organic wastewater is discharged into natural water bodies,causing serious water pollution.In addition,the organic matter in organic wastewater contains abundant chemical energy,and the discharge of organic wastewater is a waste of resources.Therefore,the treatment and recycling of organic wastewater is very meaningful.The photocatalytic fuel cell（Potocatalytic Fuel Cell,PFC）is a new technology that integrates sewage treatment and power generation.TiO₂ is widely used as the photoanode of PFC because of its high catalytic activity,stable chemical properties,resistance to light corrosion,non-toxicity and low cost.However,the TiO₂photoanode only responds to ultraviolet light and the photogenerated electron holes are easy to recombine.These shortcomings limit its development.Toward this end,herein,in order to improve the light utilization and electron transfer efficiency of the PFC system,this paper proposes to modify TiO₂/Ti photoanode with organic compound and BiVO₄.It is hoped that BiVO₄ can enhance the absorption of visible light,and organic matter can increase the specific surface area of the material and improve the electron transport performance.The main research contents and conclusions are as follows:1.Preparation and optimization of organic-BiVO₄/TiO₂/Ti photoanode:BiVO₄/Ui O-66/TiO₂/Ti,BiVO₄@PTh/TiO₂/Ti and BiVO₄@PDA/TiO₂/Ti photoanodes were successfully prepared by sol-gel method,hydrothermal synthesis method,chemical oxidation polymerization method and other methods.And optimized electrode preparation conditions including:material recombination ratio,electrode calcination temperature and electrode calcination time.（1）The optimal preparation conditions for BiVO₄/Ui O-66/TiO₂/Ti electrode are:BiVO₄ to Ui O-66 film layer ratio is 1:1,calcination temperature is450°C,and calcination time is 4 h.（2）The optimal preparation conditions for BiVO₄@PTh/TiO₂/Ti electrode are:mass ratio of PTh to BiVO₄ is 0.08:1,the calcination temperature is 200°C,and the calcination time is 4 h.（3）The optimal preparation conditions for BiVO₄@PDA/TiO₂/Ti electrode are:mass ratio of PDA to BiVO₄ is 0.10:1,the calcination temperature is 200°C,and the calcination time is 4 h.2.The optimized electrodes were characterized and analyzed,and the three modified electrodes all showed absorption of visible light.Compared with BiVO₄/TiO₂/Ti electrodes,the absorption thresholds of BiVO₄/Ui O-66/TiO₂/Ti,BiVO₄@PTh/TiO₂/Ti and BiVO₄@PDA/TiO₂/Ti electrodes all had a red shift,which broadens the light response wavelength Scope,improved the utilization rate of sunlight.At the same time,the photocurrent density of BiVO₄/Ui O-66/TiO₂/Ti,BiVO₄@PTh/TiO₂/Ti and BiVO₄@PDA/TiO₂/Ti electrodes was higher than that of BiVO₄/TiO₂/Ti indicating that the introduction of Ui O-66,PTh and PDA enhanced the transfer efficiency of photogenerated electrons.3.Discussion of PFC performance:the TiO₂/Ti,BiVO₄/TiO₂/Ti,BiVO₄/Ui O-66/TiO₂/Ti,BiVO₄@PTh/TiO₂/Ti,BiVO₄@PDA/TiO₂/Ti electrode were used as photoanode to combinate Cu₂O/Cu cathode to build PFCs,and they were applied to treat Rhodamine B（Rh B）under visible-light to evaluate their dye degradation and electricity generation performance.The research results showed that,compared with TiO₂/Ti-Cu₂O/Cu PFC and BiVO₄/TiO₂/Ti-Cu₂O/Cu PFC,BiVO₄/Ui O-66/TiO₂/Ti-Cu₂O/Cu PFC,BiVO₄@PTh/TiO₂/Ti-Cu₂O/Cu PFC and BiVO₄@PDA/TiO₂/Ti-Cu₂O/Cu PFC showed significantly enhanced power generation capacity and pollutant degradation capacity.The effect of dye wastewater treatment conditions on the performance of PFC was discussed.The best wastewater treatment conditions were:the initial concentration of rhodamine B was10 mg·L^-1,the initial p H of the solution was 3.0,and the concentration of Na₂SO₄ was 0.5mol·L^-1.4.The performance of PFC under optimal wastewater treatment conditions:（1）The electricity generation capacity and pollutant degradation efficiency of BiVO₄/Ui O-66/TiO₂/Ti-Cu₂O/Cu PFC are:Jsc is 0.26 m A·cm^-2,Voc is 0.498 V,JVmax is 29.26μW·cm^-2,FF is 0.250,and the degradation rate of Rhodamine B is 91.50%in 2 h;（2）The electricity generation capacity and pollutant degradation efficiency of BiVO₄@PTh/TiO₂/Ti-Cu₂O/Cu PFC are:Jsc is 0.48 m A·cm^-2,Voc is 0.512 V,JVmax is 59.70μW·cm^-2,FF is 0.242,and the degradation rate of Rhodamine B is 98.89%in 2 h;（3）The electricity generation capacity and pollutant degradation efficiency of BiVO₄@PDA/TiO₂/Ti-Cu₂O/Cu PFC are:Jsc is 0.42m A·cm^-2,Voc is 0.528 V,JVmax is 58.55μW·cm^-2,FF is 0.264,and the degradation rate of Rhodamine B is 97.28%in 2 h.5.This paper compared the performance of the three PFCs systems.BiVO₄@PTh/TiO₂/Ti-Cu₂O/Cu PFC and BiVO₄@PDA/TiO₂/Ti-Cu₂O/Cu PFC show more excellent battery performance and pollutant degradation efficiency,indicating that the conductive polymer modified photoanode can more effectively improve the performance of PFC.In this paper,the organic-BiVO₄ co-modified TiO₂/Ti photoanode successfully widened the visible light absorption area of the photoanode,increased the electron transfer rate,and improved the power generation capacity and pollutant degradation capacity of PFC.The research results in this paper can provide ideas and experimental data references for organically modified photoanodes.