Preparation Of BiVO₄-Based Catalysts And Its Adsorption-Photocatalytic Performance

BiVO₄catalysts were prepared by low temperature solid phase method,microwave-assisted solid phase method and microwave hydrothermal method.BiVO₄-based composite catalysts were prepared by combining with g-C₃N₄and GO.The physicochemical properties of the catalyst were characterized by XRD,SEM,TEM,UV-vis DRS,BET and FT-IR.The adsorption and photocatalytic properties of the catalysts were determined with the removal of methylene blue（MB）as the model.The effects of p H value and inorganic ions on the performance of the catalyst were investigated.The crystal morphology and adsorption photocatalytic performance of series BiVO₄were compared.Finally,the adsorption and photocatalytic properties of BiVO₄-based composite catalyst were studied,and the effects of p H value and initial concentration of MB on degradation process were discussed.The results show that:（1）For BiVO₄prepared by low-temperature solid phase method,A)When the grinding time is short,the BiVO₄is a monoclinic scheelite structure crystal,and after the grinding time is prolonged,the tetragonal zircon phase structure appears in the BiVO₄crystal.With the increase of drying temperature,the morphology of BiVO₄sample gradually changes from irregular strip to spherical shape.Prolonging the grinding time is beneficial to obtain the sample with better light absorption performance.B)The sample with drying temperature of 100℃and grinding time of 10 min has stronger photocatalytic activity.C)When the reaction conditions are that:MB concentration of 10 mg/L,catalyst concentration of 1 g/L,25℃,p H=7,the reaction for 60 min,the remaining ratio of MB is 5.8%.（2）For BiVO₄prepared by microwave solid phase method,A)BiVO₄prepared by microwave solid phase method is a miscible structure of monoclinic phase and tetragonal phase.B)When the adsorption conditions are that:MB initial concentration of 10 mg/L,catalyst concentration of 1 g/L,25℃,p H=7,adsorption for 30 min,the remaining ratio of MB is 46.2%.C)The reaction conditions are that:MB initial concentration of10 mg/L,catalyst concentration of 1 g/L,25℃,p H=7,after 60 min of reaction,the remaining ratio of MB is 14.8%.（3）For BiVO₄prepared by microwave hydrothermal method,A)Without the coordination agent,BiVO₄synthesized by microwave hydrothermal method is a monoclinic phase structure,the BiVO₄prepared by adding coordination agent is miscible structure of monocline phase and tetragonal phase.The BiVO₄prepared with cetyl trimethyl ammonium bromide as coordination agent,when the adsorption conditions are that:MB initial concentration of 10 mg/L,catalyst concentration of 1 g/L,25℃,p H=7,after adsorption for 30 min,the remaining ratio of MB is 76.8%and the equilibrium of adsorption and desorption is reached after 30min.When the reaction conditions are that MB initial concentration of 10 mg/L,catalyst concentration of 1 g/L,25℃,p H=7,after the reaction for 90 min,the remaining ratio of MB is 62.6%.（4）BiVO₄prepared by microwave solid phase method has strong adsorption property,while BiVO₄prepared by low temperature solid phase method has strong photocatalytic property.（5）Compared with BiVO₄and BiVO₄-C₃N₄,the composite catalyst BiVO₄-C₃N₄-GO has stronger photocatalytic activity.The results of the investigation of its adsorption performance and photocatalytic performance showthat the adsorption performance is gradually enhanced with the increase of p H.When p H=9,the photocatalytic activity of the catalyst is the best.