The Synthesis And Photocatalytic Water Splitting Research Of TiO₂ Spherical Photonic Crystal

With the development of science and technology,using semiconductor photocatalyst to convert solar energy into hydrogen energy to solve the energy crisis has been widely concerned by researchers.There are three main aspects that affect the hydrogenation performance of semiconductor photocatalytic:the absorption efficiency of solar light,the separation and recombination of photogenerated charges and the redox reactions on semiconductor surfaces.Among them,the photocatalytic efficiency will be directly determined by the efficiency of semiconductor capturing solar light and the recombination rate of photogenerated electron–hole.Therefore,improving the utilization efficiency of solar light and reducing the recombination of photogenerated electron hole pair become the key factors to improve the hydrogen production performance.Researchers have found that the slow photon effect of photonic crystal structure can effectively improve the photocatalytic performance of the photocatalyst.The reason are as follows:the inverse opal photonic crystal has a larger refractive index and can produce omnidirectional photonic band gap.In addition,the inverse opal structure has a higher specific surface area,which is beneficial to the contact between photocatalyst and reaction material.However,there are still some problems in photonic crystal structure in photocatalytic reaction:the dependence of photonic crystal structure?film or block?on incident light and the low photocatalytic efficiency of thin film photonic crystals.Therefore,it is worth developing a photonic crystal structure to realize the light angle independence and non-oriented slow photon for photocatalytic H₂ production.In this work,we designed and synthesized the TiO₂ spherical inverse opal photonic crystal?IO-TiO₂-S?by microfluidic technology.The spherical structure photonic crystal can realize the non-oriented slow photon effect,which can solve the dependence of the ordinary photonic crystal on the incident light angle during the photocatalytic reaction.The details are as follows:1.After a series of experiments,the TiO₂ spherical inverse opal photonic crystal was prepared by monodisperse P?St-MMA-AA?emulsion particle as templates and Ti?BALDH?solution.The optimum proportion of different sizes template was explored by changing the volume ratio of the template and precursor.2.In this chapter,the slow photon effect was realized in spherical photonic crystal by changing the sizes of polymer template.Under solar light illumination,inverse opal photonic crystal structure exhibits good photocatalytic hydrogen production performance,among which IO-TiO₂-S-360 with slow photon effect had the best hydrogen production performance of 62 mmol g^-1.3.Based on the previous experiments,the photocatalytic hydrogen production performance of IO-TiO₂-S was improved by supporting single atom Pt on the photocatalyst surface to reduce the Pt load.After a series of characterizations,it was found that Pt loaded on IO-TiO₂-S had two forms single atom and nanocluster.The experiment results show that IO-TiO₂-S supported single atom Pt as cocatalyst could be achieved higher photocatalytic performance and the hydrogen production capacity was 139 mmol g^-1 in 5h.