Study On Bi₂O₃/TiO₂/BiOI Photocatalysis/Photocatalytic Fuel Cell

With the improvement of people’s awareness of environmental protection and the increasing requirements for environmental quality,there will be a new challenge for how to treat sewage safely and effectively.Photocatalysis（PC）using sunlight has high efficiency and without secondary pollution,which has always been a hot direction in the research field.PC can produce non-selective oxidation active particles（hydroxyl radical·OH,photogenerated hole h⁺and superoxide radical·O2^-）under the excitation of light using photocatalytic semiconductor materials.The organic pollutants in sewage can be mineralized into inorganic small-molecules such as CO2and H2O by the active particles,for the purpose of purifying sewage.Photocatalytic fuel cell（PFC）has the advantages of PC and fuel cell（FC）.It can not only degrade organic pollutants effectively,but also can convert chemical energy in sewage to electric.PFC can also be applied widely because of its recyclability.Though,it is explored new efficient photocatalytic materials,preparation methods of photoelectric electrode（photoelectric electrode is the most important part of PFC）as well as assembly methods of PFC in this paper:1.The core-shell structure Bi2O3@Ti O2 was successfully prepared by two-step solvothermal method.The composite samples were characterized by corresponding characterization soon.Compared with Ti O2,composite photocatalyst has lower recombination of photogenerated electron-hole pair（e^--h⁺）and higher visible light utilization.The effects of different hydrothermal time,hydrothermal temperature and other preparation processes were studied.And it was found that h⁺and·OH plays major roles in Rhodamine B（Rh B）degradation through the active particle capture experiments.2.Three dimensional Ti O2-Bi OI photocatalyst with nanoflower structure were synthesized by solvothermal method.The composite samples were characterized by FESEM,HRTEM,EDS and XRD.The results showed that Ti O2 was successfully coupled with Bi OI and composite photocatalyst has lower e^--h⁺recombination.Through the degradation of different organic compounds such as Rh B,methyl orange（MO）and tetracycline（TC）,the experiment shows that Ti O2-Bi OI with heterostructure possess higher photocatalytic activity under visible light than Bi OI and Ti O2.It was also found that h⁺and·O2^-play major roles in Rh B degradation by Ti O2-Bi OI,and its Rh B photocatalytic degradation constant is 5 times more than that of Bi OI.3.In order to solve the shortcomings of difficult recovery and insufficient application of powder catalyst,Bi2O3@Ti O2 film electrode was successfully prepared by tape-casting on the fluorine doped tin oxide（FTO）film.Platinum electrode was used as photocathode,and Bi2O3@Ti O2 film electrode was used as a photoanode.Then the photocathode and photoanode were connected by the wires to assemble as a planar photocatalytic fuel cell（p-PFC）.The effects of different metal cathodes,cell structures and organic substrate concentrations on the photocatalytic performance of p-PFC were studied in this paper.Compared with the photocatalytic experiments,it was found that the Rh B degradation rate of p-PFC can be reached 93.08%to that of PEC.Finally,the main mechanism of Rh B degradation by p-PFC was explored by active particle capture experiments.which was showed that the main active groups in the degradation of Rh B by PFC system were photogenerated hole（h⁺）and hydroxyl radical（·OH）,the results of which is similar to the powders of Bi2O3@Ti O2.And it was showed that the semiconductor photocatalytic materials play a major role in the p-PFC system.4.Because of the high price of noble Pt electrode and its light weak response ability.Ti O2-Bi OI composite catalyst was selected as the cathode to replace the traditional Pt electrode in order to further improve the application of PFC.Ti O2-Bi OI film electrode was successfully prepared by the same preparation method for tape-casting,and the two electrodes were assembled into a binary photocatalytic fuel cell（b-PFC）with the forms of“back to back”.The experimental results show that the existence of PFC system improves the photocatalytic efficiency of photoanode,and the Rh B degradation rate of binary PFC is higher,which is 1.15 times than Bi2O3@Ti O2/Pt photocatalytic fuel cell through the same photocatalytic experiments.