Fabrications Of In₂O₃ Nanocatalysts With Different Micro-Morphologies And Crystalline Phases And Their Photocatalytic Properties Of Degrading Toluene

As one of advanced oxidation processes, photocatalytic degradation of organic pollutants is playing an important role in the field of environmental pollutant control. As a photocatalytic material, In2O3 has some advantages such as high light-responding ability, strong chemical stability, strong thermal stability and easy to synthesize various microstructures. These advantages make In2O3 very valuable for the application in photocatalytic degradation of organic pollutants. However, the wide band-gap of In2O3 causes its inactivity under visible light, which occupies the major part of solar light. Besides, another shortcoming hindering its practical application is its high recombination rate of photo-induced charges. These disadvantages limited the photodegradation efficiency of In2O3. In this paper, we enhanced the photocatalytic activity of In2O3 via micro-morphology control and crystalline phase control. The main investigation was carried out as follows:(1) The bcc-In2O3 photocatalysts with different morphologies, which including hollow microspheres and solid microshpheres and amorphous nanoparticles, were prepared via a solvothermal process. And the micro-morphology control of In2O3 photocatalytic material was achieved. Then, the structural properties of as-prepared samples were investigated by XRD, SEM, TEM, DRS and nitrogen adsorption-desorption. The results indicate that as-prepared sample of hollow microspheres has a typical hollow thin-shell micro-morphology. And its light-absorbing boundary reach 480 nm, pore size distribution concentrates on 2～10 nm, and the specific surface area is 73.8 m2/g. Therefore, it should have stronger photocatalytic activity. Meanwhile, we studied the photocatalytic activities of the as-prepared samples of In2O3 with different morphologies for the decomposition of gaseous toluene under simulated sunlight irradiation. The results indicate that the degradation rate of as-prepared hollow microspheres reaches 97.21% when the reaction time is 5 h. Besides, as-prepared samples were investigated by ESR. And the result shows that the as-prepared sample of hollow microspheres can create more active radicals.(2) The In2O3 photocatalysts with different crystalline phases, which including bcc-In2O3 and rh-In2O3 and bcc-/rh-In2O3, were prepared via a solvothermal process. Besides, the crystalline proportion can be controlled by changing reaction time. Therein, the crystalline control of In2O3 photocatalytic material was achieved. The structural properties of as-prepared samples were investigated by XRD, SEM, TEM, HRTEM and DRS. The results indicate that as-prepared bcc-/rh-In2O3 mixed-crystalline sample has a strawberry-like micro-morphology. And the plane of different crystal is overlapped each other, which is easy to create a heterogeneous junction. Its light-responding ability in visible region is 5 times than single-crystalline samples. we studied the photocatalytic activities of the as-prepared samples of In2O3 with different crystalline phases for the decomposition of gaseous toluene under simulated sunlight irradiation. The results indicate that the as-prepared bcc-/rh-In2O3 mixed-crystalline sample has the best degradation efficiency (reach 97.65% at 5 h).