Photoelectrocatalytic Degradation Of Organic Wastewater With Composite Semiconductor Electrodes

Photocatalytic and electro-catalytic oxidation technologies have the advantages of small energy consumption,complete degradation,and no secondary pollution,and are widely used in organic wastewater treatment processes.In order to improve the photocatalytic/electrocatalytic oxidation efficiency,photoelectrocatalytic technologies?including electro-assisted photocatalytic and photoelectrocatalytic processes?combine the advantages of both photocatalytic and electrocatalytic technologies to achieve the synergy between the two.This will increase the efficiency and applicability of organic wastewater treatment.In this study,the traditional photocatalyst TiO₂ and electrocatalyst PbO₂ as the research object,through the modification to improve the electrode physicochemical properties,and the use of photoelectric processes to achieve efficient degradation of organic wastewater.The main research content is as follows:?1?A highly oriented black TiO₂ NTAs/Ti?nanotube array?electrode was fabricated by electrochemical anodic oxidation-reduction process using Ti as a substrate.The effects of reduction voltage and reduction time on the properties of the black TiO₂ NTAs/Ti electrodes were investigated.The results show that the electrochemical reduction does not change the structure of the TiO₂ NTAs/Ti crystals?still anatase structure?,but the self-doping of Ti³⁺is realized.The obtained black TiO₂ NTAs/Ti electrode has stronger UV-visible absorption,more negative flat band potential and better photo-generated charge separation efficiency.Compared with the unreduced TiO₂ NTAs/Ti electrode,the black TiO₂ NTAs/Ti electrode shows a higher photoelectrolytic degradation efficiency?84%?of the reactive brilliant blue dye KN-R.However,over-voltage reduction will destroy the porous structure of the nanotube electrode,resulting in decreased activity.?2?P25-PbO₂/Ti electrode was prepared by electrodeposition.The effect of P25 addition on PbO₂/Ti electrode was investigated.The results showed that due to the incorporation of P25,the orientation growth of PbO₂[101]and[301]planes was inhibited,and the oxygen evolution reaction of PbO₂/Ti electrode was inhibited,which caused the negative shift of the flat band potential and enhanced the electrochemical activity area of the electrode and hydroxyl radical generation ability,In addition,the photocatalytic activity of PbO₂/Ti was improved.The photodegradation efficiency of reactive brilliant blue KN-R reached 91%.?3?Hexagonal boron nitride nano-particles were prepared by high-temperature thermal decomposition method to obtain BN nano-particles as additives,and BN-PbO₂/Ti electrodes were obtained by electrodeposition.The results of various characterizations show that the introduction of BN significantly changes the morphology of PbO₂ crystals?BN nanoparticles are embedded on the surface of the crystal,and the high adsorption capacity of BN can effectively improve the reaction process at the electrode surface?,and improves the electrochemical active area of PbO₂ electrode and the formation of hydroxyl radicals on the surface.Compared with the PbO₂/Ti electrode,the BN-PbO₂/Ti electrode exhibited higher photoelectrocatalytic degradation efficiency and stability of Reactive Brilliant Blue KN-R with a degradation rate of up to 94%.?4?Firstly,TiO₂ nanobelts were prepared by hydrothermal method,and PbO₂nanospheres-TiO₂ nanobelts/Ti electrodes were prepared by secondary hydrothermal reaction.The results show that PbO₂ and TiO₂ crystals obtained by hydrothermal method are?-PbO₂and anatase TiO₂,respectively.The composite of PbO₂ not only enhances the light absorption ability of the TiO₂/Ti electrode,but also forms a semiconductor heterostructure,which in turn enhances the photocatalytic oxidation of TiO_2.Degradation of 60mg/l reactive brilliant blue dye under irradiation of ultraviolet light can reach a degradation rate of 86%,which is about20%higher than that of TiO₂/Ti electrode.Compared with the traditional TiO₂ photocatalyst,the composite catalyst has significantly improved the degradation of pollutants.Therefore,electro-assisted photocatalytic technology can be considered as one of the promising and promising methods for treating organic contaminants in water.