Synthesis Of Niobate Nanosheet/polymer Composite Microgel Particles Through Microfluidic Approach Toward Photocatalytic Applications

Recently,fabrication of microgels through microfluidic technology has attracted considerable attention due to the unique advantages such as simple operation,good monodispersity,control of particle size and great potential for industrial production.Inspired by this technology,niobate nanosheet/polymer composite microgel particles have been prepared by using a self-made microfluidic device.The microgels were utilized as catalyst carriers for nanosheets to prevent aggregation of nanosheets and realize convenient recycling of catalysts.First,the microfluidic device was manufactured through micromachining technology.Then microgel particles were prepared.We concluded that the size of microgels decreases with the increase of viscosity of oil phase,the increase of hydrophile lipophilic balance number and concentration of surfactant,as well as the increase of flow rates of oil phase relative to water phase within a certain range.Second,composite microgels were prepared by both redox polymerization and photopolymerization.The composite microgels exhibited photodegradation ability of Rhodamine B and methyl orange under UV light irradiation.The photocatalytic performance gradually enhanced with the increase of nanosheets concentration and the decrease of microgel size.Furthermore,composite microgels prepared by photopolymerization displayed higher photocatalytic activity.According to observation from a crossed polarizing microscope,we inferred that the introduction of ammonium persulfate can cause slight aggregation of niobate nanosheets during the redox polymerization,which will lead to the reduction of specific surface area and poor dispersion of nanosheets in the microgels.While the dispersion of the nanosheets embedded in the photopolymerized composite microgels was relatively better.Because niobate nanosheets are able to generate free radicals to induce polymerization under UV light irradiation.Subsequent kinetic studies demonstrated the photodegradation of dyes was consistent with the rule of pseudo-first order reaction.Meanwhile,the degradation rates of Rhodamine B were above 95% in three cycles catalytic test indicating the composite microgels maintained excellent photocatalytic performance after exposure to UV light for 3 hours.In addition,the domination of superoxide radicals in the photodegradation reaction was revealed by photoinduced carriers trapping test.