Photocatalytic Electrode Synergizes With Multiple Mechanisms To Eliminate Nitrogenous Odor Air Pollutants

Photocatalytic technology has high application value in the field of air purification.However,the single photocatalytic technology has many problems in practical applications,such as low quantum efficiency,low photocatalytic efficiency,high cost,and difficulty in loading and separating and recycling photocatalysts.Therefore,it is necessary to coupling photocatalysis technology with other advanced oxidation technologies or efficient pollution control methods to improve the application of photocatalysis.At the same time,the choice of photocatalyst is an important way to improve the photocatalytic effect.Finding a catalyst with excellent electrochemical performance,wide optical absorption,low photogenerated carrier recombination rate and low cost as the photocatalytic electrode material is also the key to solving the problem.In this paper,photocatalytic technology was coupled with electrochemistry,microbial fuel cell and persulfate activation technology to form three coupling systems,and then three catalysts were synthesized by different methods to degrade nitrogenous pollutants ammonia and trimethylamine gas,respectively.The main results of this paper are as follows:?1?Sn-V₂O₅ nanoparticles were synthesized by sol-gel method,which can effectively remove ammonia in PC?photocatalysis?,PEC?photoelectrocatalysis?or PEC-MFC?photocatalytic coupling microbial fuel cell?at room temperature.The structure and electronic properties of Sn-V₂O₅,the effect of Sn doping and the active species produced during ammonia degradation were studied.The doping ratio of Sn affects the catalytic activity.When the content of Sn is 1wt%,Sn-V₂O₅ shows the best degradation effect?NH₃ removal rate is96.4%?and stability.By integrating PC with electrocatalysis and microbial fuel cells in one system,the removal effect can be improved?remove ammonia almost completely?.Oxygen vacancies and the appropriate amount of Sn loading play a key role in ammonia oxidation:Oxygen vacancies can generate reactive oxygen for oxidizing ammonia gas,which could maintain the reaction continuous;Excessive Sn loading will form a recombination center for photogenerated electron-hole pairs,increasing the recombination rate of photogenerated carriers,thereby reducing the photocatalytic activity.This work provides an innovative and stable photocatalyst for air purification and odor control.?2?Photocatalytic synergistic persulfate activation system?PEC/PS?was innovatively constructed,and the heterogeneous CuO-Co₃O₄ catalyst was synthesized by ion co-precipitation method to study the degradation effect of ammonia.CC-21?Cu/Co=2:1?was selected as the best catalyst by means of the control experiments of ammonia degradation and the characterization of the catalysts.By comparing the degradation rate of ammonia gas under three conditions:1)supported with catalyst and PS or PMS,2)only catalyst,3)only PS or PMS on the electrode,it was found that both PS and PMS could promote the oxidation of ammonia.Different metal anodes have great influence on the degradation effect of ammonia gas.Copper rod is more suitable as anodes for the degradation of ammonia gas.The experimental results show that the PEC/PS system can remove 96.1%of NH₃ at room temperature,in which the external resistance and the concentration of PS are optimally 100?and 0.135 M,respectively.In addition,the power generation capacity of the PEC/PS system is high,with the voltage more than 0.83 V.The photocatalytic synergistic in-situ PS activation accelerates the generation of free radicals in PEC/PS system,thereby enhancing the electrochemical catalytic oxidation and removal of ammonia for CuO-Co₃O₄.?3?Co-MoS₂ catalyst with nanopetal-like structure was synthesized by hydrothermal method,which can degrade trimethylamine gas rapidly and effectively in PEC system.Co-MoS₂ catalyst has a petal-like structure with a large specific surface area,which can improve the catalytic performance.TMA degradation experiment results show that the Co-MoS₂ catalyst can degrade TMA in PEC system within 35 min,and has higher photocatalytic activity and apparent quantum efficiency.The stability of Co-MoS₂ catalyst in the degradation of TMA in PEC system is better than that of PC,which is due to the existence of external bias generated by auxiliary electrochemistry in PEC system.In summary,composite catalysts with high photocatalytic activity,such as Sn-V₂O₅,CuO-Co₃O₄,and Co-MoS₂,were prepared in this study,and photocatalytic coupling system or photocatalytic synergistic persulfate activation system were constructed,which can degrade ammonia and trimethylamine pollutants efficiently at room temperature.