Luminescent Carbon Dots Assembled Mesoporous Silica Materials And Its Oxygen Sensing Properties

A kind of opitc oxygen sensor based on fluorescence quenching has been studied,which is composed of light-emitting molecular being susceptible to oxygen concentration and carrier diffusing fastly of oxygen molecules.Recently,researchers have proposed various materials especially glowing metal complexes for the sensing of oxygen,such as the ruthenium?II?.While the limited practical application of glowing metal complexes was based on the high price,environment unfriendly and these synthesis processes are complicated and time-consumed.Comparing with traditional luminescent species,fluorescent carbon dots?CDs?exhibit great potential in sensors,light-emitting diodes?LEDs?and others due to their nontoxic,low cost,excellent chemical and photostability as well as superior optical properties.In an oxygen sensor,a high diffusion coefficient of gas is necessary for a rapid response,a highly locally effective quenching around the oxygen probe is useful for good sensitivity.Among the mesoporous materials for loading of CDs,mesoporous silica materials are particularly attractive due to the thicker wall,uniform pore size,large surface area and high chemical stability,which would allow direct incorporation into oxygen sensing.Herein,we successfully prepared mesoporous silica materials by hydrothermal method.Among them,SBA-15 was prepared by Triblock copolymer(EO₂₀PO₇₀EO₂₀)as the structure-directing agent and MSMs were prepared by using STAB,CTAB and TTAB as the structure-directing agent,and TEA as the co-template under mild conditions.Direct impregnation method was used to incorporate the CDs into mesoporous silica materials,and its oxygen sensing properties was investigated.Due to the concentration quenching of CDs caused by aggregation,the CDs highly loaded mesoporous silica materials only present slightly increasing emission intensity.These results indicate that the system we have developed can be used for oxygen detection in the whole range and is especially accurate for very low oxygen concentrations.The specific selectivity and sustained high response arise from the hybrid materials that are an irreplaceable materials in sensitivity and anti-interference of oxygen sensor.More importantly,this method can be easily copied by other better light-emitting molecular assembly into the carrier for better performance.We hope that our work can inspire researchers to develop new types of oxygen sensing materials or equipment.It is well suited as a matrix that SiO₂ nanoparticle can contain individual light-emitting molecular,such as CDs and Eu³⁺,with mesopores to obtain oxygen sensing material,and the pores are wide enough to permit facile diffusion of reactants and products.Ratiometric fluorescent methods can be used to detect oxygen concentrations by measuring the change of the ratios of photoluminescence?PL?intensities at two wavelengths,which possess a built in correction that eliminates false signals emanating from environmental effects and therefore increases signal accuracy.In addition,the as-obtained CDs/CaAlSiN₃:Eu²⁺-silica powder has a core-shell structure by a one-pot sol-gel method through the hydrolysis of TEOS and BTEE.Red light promotes the radial growth of plants,and blue light is propitious to the transverse extension.LED grow devices were fabricated by using the dual-emitting CDs/CaAlSiN₃:Eu²⁺-silica powder,and it was confirmed applicable possibility as lighting source for plant growth with multi-wavelength emission?red and blue light wavelength?.As a result,the advantage of there LED grow devices could be achieved by the as-prepared blue-emitting CDs and red-emitting CaAlSiN₃:Eu²⁺phosphor which packed together as color converters onto a UV-LED chip to construct LED grow light.The LED grow devices are costing and time-consuming less than the traditional two LED chips assembled system.And it is convenient,low-costing,non-toxic and inherent stable compared with traditional LED light.