Synthesis Of Novel BiOCl Photocatalysts And Improvement Of Photocatalytic Performance Under Visible Light

Photocatalytic technology has been widely used due to its low energy consumption,wide application range,high efficiency,and no secondary pollution.The core of photocatalytic technology is photocatalyst.Whether it can synthesize an efficient and non-polluting photocatalyst is the most critical factor in solving environmental problems.Due to its special layered structure,BiOCl has become the focus of research on the separation efficiency of high photoelectron and electron holes.However,BiOCl has a wide bandgap and cannot use visible light in solar energy.Therefore,the modification of BiOCl in three aspects of the defect state regulation,the regulation of the morphology structure and the regulation of the energy band structure is used to improve the photocatalytic performance under visible light.The study is as follows:?1?The square-sharped BiOCl nanosheets with oxygen vacancies were successfully synthesized via a facile hydrothermal route using xylitol as surfactant.The as-prepared BiOCl samples were characterized by Powder X-ray Diffractometer?XRD?,scanning electron microscope?SEM?,transmission electron microscopy?TEM?,high-resolution transmission electron microscopy?HRTEM?,selected area electron diffraction?SAED?,UV–Vis diffuse reflectance spectra?DRS?,Brunauer–Emmett–Teller?BET?,X-ray photoelectron spectroscopy?XPS?and Electron spin resonance?ESR?.The as-prepared samples were phase-pure with the width and the thickness were about 50-400 nm and20-50 nm respectively.Besides,the photodegradation performances showed the BiOCl nanosheets with 0.1 g concentration of xylitol?BOC-1?had the best photocatalytic activity under visible light due to its special polycrystalline structure,grain boundary and an optimum concentration of oxygen vacancies.The h⁺and·O₂^-were the two main active species during the photocatalytic process and the possible photocatalytic mechanism was proposed.?2?The porous,highly crystalline BiOCl nanosheets were successfully synthesized via a facile hydrothermal route using mannitol as surfactant.Characterization results show that the as-prepared samples with a width and thickness of 50-200 nm and 20-50 nm,respectively.Besides,the photodegradation performances showed that the BiOCl nanosheets with 0.1 g concentration of mannitol?BOC-1?exhibited the best photocatalytic activity under visible light due to its highly crystalline,porous structure and positive valence band.The h⁺and·O₂^-were the two main active species during the photocatalytic process and the possible photocatalytic mechanism was proposed.?3?Using sodium citrate as a surfactant,a spheroidal?BiO?₂CO₃/BiOCl composite photocatalyst composed of nanosheets was successfully synthesized by hydrothermal method.Characterization results show that the prepared sample was composed of some spherical?BiO?₂CO₃/BiOCl composite photocatalysts stacked with some irregular nanosheets,and the thickness of the nanosheets was 10-20 nm.In addition,photodegradation performance experiments show that the sample prepared with 0.1 g of sodium citrate surfactant exhibits the best photocatalytic activity under visible light,which is related to its larger specific surface area and energy band structure.In the photocatalytic process,·OH radicals are the main active species and possible photocatalytic mechanisms are proposed.