Study On Hydrogen Production Mechanism Of Photoelectric Catalytic Pyrolysis Of Strontium Titanate-based Materials

With the development of economy and society,the natural environment is being destroyed.At the same time,coal,oil,natural gas and other resources,which are the main energy sources,are gradually exhausted.Therefore,the new energy with the characteristics of green,clean and high conversion efficiency,has broad research prospects.Research shows that fuel cells have conversion efficiency of up to 60%,and the raw material is secondary energy hydrogen energy,which indicates that fuel cells are expected to become a new alternative green energy.The preparation of hydrogen is the most important step in fuel cell,and photoelectric catalytic cracking of aquatic hydrogen is the most promising hydrogen production scheme at present.In this paper,SrFe_xTi_1-xO_3-?materials are taken as the research object.Through the selection of photocatalytic materials,the construction of photocatalytic system and the performance test of photocatalytic materials,the performance regulation mechanism of each system is discussed.The main contents and conclusions are as follows:In this experiment,nano-sized SrFe_xTi_1-xO_3-??x=0,0.2,0.4,0.6,0.8,1.0?semiconductor photocatalytic materials were synthesized by high-energy ball milling method,and some of them were characterized by XRD and TEM.The results show that the average particle size of SrTiO₃ is 18.44 nm,and the average particle size of SrFeO_3-?is 14.58 nm.The materials are well distributed and the crystal structure is perfect.SrFe_xTi_1-xO_3-??x=0,0.2,0.4,0.6,0.8,1.0?and the commercially purchased SrTiO₃ and TiO₂ semiconductor photoelectrodes;the reaction system conditions were optimized,including light source spectrogram test,material absorption spectroscopy test and reaction concentration selection.The photocatalytic reaction system was set up,and the open-circuit voltage,the flat-band potential of the dark and LED and the electrochemical performance of the dark and LED photocurrent were tested.The results showed that the semiconductor material with the best electrochemical performance was SrFeO_3-?.The hydrogen production rate of SrFeO_3-?was calculated to be 1.865×10^-3 mL/h.Then the band gap of the material was determined by UV-vis DRS test and PL test,and compared with the results of traditional calculation.Finally,the hydrogen production mechanism of SrFeO_3-?was explained in depth from the energy band point of view.The specific experimental results are as follows:?1?The results of open-circuit voltage analysis show that the synthesized SrFeO_3-?material is-0.0128V,and the other materials are positive.The maximum synthesized SrTiO₃material is 0.1714V,and the minimum purchased TiO₂ material is 0.0063V.The preliminary judgment of negative open-circuit voltage is beneficial to the experiment.?2?Mott-Schottky curve analysis of dark and LED illumination shows that the synthesized SrFe_xTi_1-xO_3-??x=0,0.2,0.4,0.6,0.8,1.0?series are P-type semiconductors,while the purchased SrTiO₃ and TiO₂ are N-type semiconductors.Among them,the flat-band potential of synthesized SrFeO_3-?is smaller and the flat-band potential of LED illumination decreases the most,indicating that the synthesized SrFeO_3-?has the most advantage over other materials in light response.?3?According to the I-T curve,the optical response ability of these materials was ranked as commercially purchased SrTiO₃,SrFeO_3-?,commercially purchased TiO₂,SrFe_0.8Ti_0.2O_3-?,SrFe_0.2Ti_0.8O_3-?,SrFe_0.4Ti_0.6O_3-?and SrFe_0.6Ti_0.4O_3-?,SrTiO₃.Due to the limitation of purchase of SrTiO₃,the light response ability of SrFeO_3-?is the most prominent.?4?According to the electrochemical performance test,the best selective SrFeO_3-?semiconductor electrode was used for photocatalytic cracking of aquatic hydrogen.The hydrogen production rate was 1.865×10^-13 mL/h.The quantum efficiency of hydrogen?relative to the light source?was 19.34%,the photogenerated carrier efficiency of synthesizing SrFeO_3-?was 34.26%,and the hydrogen equivalent to the photogenerated carrier efficiency was 56.45%.?5?The band gap of photocatalytic materials was measured by UV-visible diffuse reflectance spectroscopy and photoluminescence spectroscopy.The results were similar to those obtained by traditional calculation,and then the electrochemical and photoresponse properties of materials were explained from the energy band angle.?6?The mechanism of aquatic hydrogen production by photocatalytic pyrolysis of SrFeO_3-?materials was analyzed and explained.