Study On The Enhancement Of Charge Separation And Photocatalytic Activities Of BiOCl

BiOCl photocatalysts have attracted much attention in recent years due to their unique layered crystal structures and electronic band structures.However,low separation and transfer of photocarriers and utilization of light are the key factors limiting their photocatalytic efficiency.This paper aims at solving the above problems.BiOCl with exposed{001}and{010}were prepared via one step hydrothermal or hydrolysis method.The photocatalytic reduction and degradation performance of BiOCl-（001）were better than that of BiOCl-（010）due to the higher efficiency of charge separation and migration of BiOCl-（001）.The better charge separation of BiOCl-（001）is due to the internal electric field along the[001]direction in BiOCl crystal structure that facilitating the separation of photogenerated charge carriers and the capture of photoexcited electrons by active sites which is the unsaturated atoms on{001}facet.This work provides new insight into the understanding of facet dependent charge separation and transfer behavior.The eighteen-faceted BiOCl polyhedra exposed{001}top facet,{112}side facet and{102}oblique facet was synthesezed by a prolonged hydrothermal method.The photocatalytic activities for H₂ and·OH production of eighteen-faceted BiOCl polyhedra under simulated sunlight is much higher than that of BiOCl square plates.The photoelectrochemical mesearment results illustrate that the improvement of the photocatalytic performance of eighteen-faceted BiOCl polyhedra is due to the enhancement of charge separation and migration efficiencies.It’s found that there is a well matched{001}/{102}/{112}ternary facet junction in eighteen-faceted BiOCl polyhedra.The photogenerated electrons flow from{112}facet to{102}facet and further to{001}facet,forming a cascade charge flow.The photodeposition experiment further verified that the spatial separation of reduction and oxidation active sites in eighteen-faceted BiOCl polyhedra.This work not only provides a new strategy for the synthesis of layered materials with polyfacet exposed but also offer a novel perspective for the enhancement of charge separation and photocatalytic activity.The C/BiOCl composite photocatalytic materials were prepared by in-situ deposition of BiOCl nanosheet on the surface of biochar,a low cost and easily obtainable material.As a good carrier for promoting the photoreaction,biochar enhcances the light absorption and charge separation of composite materials.Moreover,the photocatalytic performance under visible light is further improved.This work has certain guiding significance for the development of low cost composite photocatalytic materials.Oxygen and chlorine dual-vacancies BiO_1-xCl_1-y was prepared through a simple and environmentally friendly reduction strategy using extracting solution of green tea and spinach innovatively.The visible light response range and photogenerated charge separation of BiO_1-xCl_1-y are greatly improved.Theoretical calculation shows that there are two defect energy levels in BiO_1-xCl_1-y because of the existence of vacancies.Due to the significantly enhanced light absorption and charge separation,BiO_1-xCl_1-y exhibits excellent photocatalytic degradation of RhB and NO and high selective reduction of CO₂ to CO.In addition,the synthesis of BiO_1-xBr_1-y and BiO_1-xI_1-y-y proved that this method was suitable for bismuth halide materials.This work not only provides an idea for designing of crystal defect engineering by environmentally friendly nature-derived method but also offer a reference for the improvement of photocatalytic properties by dual-vacancies.