Synthesis And Application Of Photoluminescent Molybdenum Oxide Quantum Dots

As a novel TMO nanomaterial,molybdenum oxide nanomaterial has drawn tremendous attention for its excellent optical,electrical,catalytic and mechanical properties.At present,molybdenum oxide nanomaterials with different morphologies have been synthesized and applied in many aspects including biochemical sensing,catalysis and lithium-ion battery.However,almost all of the synthesis methods are demanding tedious procedure,time-consuming,or requiring harsh reaction conditions.Moreover,only a few reports mentioning the photoluminescence property of Mo O_x nanomaterials are available,not to mention its applications as fluorescence probes in chemical and biological sensing.Therefore,the development of a rapid,one-pot and environmentally friendly methods for the large-scale synthesis of photoluminescent Mo O_x nanomaterials and its further application are still challenging.Herein,photoluminescent molybdenum oxide quantum dots（Mo O_x QDs）were prepared by a one pot method at room temperature,which was further used as a new type of fluorescent probe in environmental pollutions and thiol group containing molecules analysis.The contents of this paper are summarized as follows:（1）Preparation of the Mo O_x QDs.A one-pot method was developed for facile synthesis of highly photoluminescent Mo O_x QDs,in which commercial molybdenum disulfide powder（Mo S2）and hydrogen peroxide（H₂O₂）were involved as the precursor and oxidant,respectively.Compared with current synthesis methods,the proposed one has the advantages of rapid,one-pot,easily prepared,environment friendly as well as strong photoluminescence.（2）Environmental pollutionsr analysis based on Mo O_x QDs.A novel off-on photoluminesce sensor for Pi using Mo O_x QDs as photoluminescent probe due to the fact that Eu³⁺ ions displays a higher affinity to oxygen atoms from Pi than Mo O_x QDs.With the present off-on sensing platform,a good linear relationship was found between the enhanced photoluminescence intensity and Pi concentration in the range of 0.1¹60.0 mM with the detection limit of 56 n M（3s/k）.What’s more,Pi in lake water samples could be rapidly and selectively detected without tedious sample pretreatment processes,and the accuracy and repeatability are acceptable for Pi detection in lake samples.In addition,a new turn-off sensor was developed for 2,4,6-trinitrotoluene（TNT）determination based on the fact that the photoluminescence of Mo O_x QDs was quenched by the Meisenheimer complexes formed in the strong alkali solution through the inner filter effect（IFE）.A good linear relationship was found between the photoluminescence intensity and TNT concentration in the range of 0.5²40.0 mM with the detection limit of 0.12 mM（3s/k）.With the present turn-off sensor,TNT in water samples can be rapidly and selectively detected without tedious sample pretreatment processes.（3）The detection of thiol-containing compounds based on Mo O_x QDs.As a common quencher,Cu²⁺ can quench the photoluminsecence of Mo O_x QDs（switch off）through static quenching processes while the formed Mo O_x QDs-Cu²⁺ complex might be dissociated by the higher affinity between Cu²⁺ and-SH,resulting the fluoresence recovery of the Mo O_x QDs.Therefore,a new sensing platform for captopril（Cap）detection was developed based on Mo O_x QDs and Cu²⁺,and Cap in pharmaceutical samples was successfully determined with high sensitivity and good repeatability.Additionally,thiocholine（Tch）,generated from the hydrolysis reaction of ATCl catalyzing by ACh E,will reacts with Cu²⁺,leading to restore the photoluminescence of Mo O_x QDs and to provide a facile switch-on sensor for ACh E activity detection.In the presence of inhibitors,such as propazine,chlorpyriphos,diazinon and monocrotophos,the enzyme activity of ACh E was inhibited and TCl cannot be generated.As a result,the photoluminescence of Mo O_x QDs was still quenched by Cu²⁺ and a facile switch-off sensor for ACh E inhibitor screening was constructed herein.Under the optimized conditions,the linear range for Ach E activity ranges from 0.1 to 15.0 m U/m L and the detection limit is 0.08 m U/m L,and Ach E inhibitors including propazine and chlorpyrifos and other inhibitors displayed a good inhibitory effect.In summary,a one pot method was developed for facile synthesis of photoluminescent molybdenum oxide quantum dots（Mo O_x QDs）at room temperature,which was further used as a new type of fluorescent probe in environmental pollutions and thiol group containing molecules analysis.