Construction And Application Of SERS Substrate Containing MXenesheet

In recent years,Surface-enhanced Raman spectroscopy（SERS）has become a promising rapid analysis technology.It has good sensitivity and can provide rich structural information of the object to be measured.Therefore,it is likely to be widely used in environmental detection and other fields.In order to apply this technology to practical analysis and detection,the key is to develop SERS substrate with high sensitivity and selectivity,high repeatability and reproducibility.As a new 2D nano-material with graphene-like properties,MXenesheet has good application prospects in the development of new SERS substrates.It is possible to prepare highly sensitive SERS substrate by combining it with other functional materials.For this reason,in this paper we have constructed a series of SERS substrates containing MXenesheet,and investigated their SERS effect on organic pollutants and the possibility of their application in the trace detection of pollutants in water.The main research contents and results are as follows:（1）Using polyvinyl alcohol（PVA）as self supporting framework,a dry gel composed of PVA and MXenesheet was prepared.Then,Ag nanoparticles were modified on the above dry gel（PVA-MXene-Ag）by in situ reduction technology.On this basis,the effects of the content of MXene nanoparticles,the loading amount of Ag nanoparticles,and the reduction reaction time on the SERS effect of PVA-MXene-Ag were studied using Rhodamine 6G（R6G）as the probe molecule.We found that PVA-MXene-Ag is a SERS substrate with ultra-high sensitivity to R6G.The minimum detection limit of R6G can reach 10^-16 mol L^-1.At the same time,we also found that PVA-MXene-Ag has good repeatability and reproducibility.In addition,we used this highly sensitive substrate to further explore the selectivity of SERS substrate of MXenesheet modified with Ag nanoparticles,meanwhile,pave the way for our further research.（2）A thin film（Ag-PVA/MXene-PDDA）composed of Ag nanoparticles,PVA/MXenesheet gel and Poly dimethyl diallyl ammonium chloride（PDDA）was constructed on Ti sheets by layer by layer assembly and in-situ reduction technology.Subsequently,the SERS effect of Ag-PVA/MXene-PDDA on benzotriazole（BTA）in water was investigated.Through research,we found that Ag-PVA/MXene-PDDA is a SERS substrate with high sensitivity to BTA.The minimum detection limit of BTA is 0.01 nmol L^-1.In addition,the substrate also has good signal repeatability（RSD between points<10.7%）and reproducibility（RSD between batches<6.2%）.Finally,we systematically discussed the possibility of practical application of Ag-PVA/MXene-PDDA,and found that it has good anti-interference ability,and also has ultra-high sensitivity for trace BTA in tap water.The minimum detection limit reached 0.1 nmol L^-1.In addition,in a wide range of BTA concentration,there is a good linear relationship between the SERS signal intensity on Ag-PVA/MXene-PDDA and the BTA concentration in water.These results show that the substrate can be used for the rapid qualitative and quantitative determination of trace BTA in water.This provides a new method for building the BTA early warning monitoring sensing platform in the future.（3）MXene films with an ordered layered structure were fabricated on Al plates via electrodeposition.Next,the Ag nanoparticles were modified on the MXene films through in situ reduction.Meanwhile,the produced composite materials surface enhanced Raman scattering（SERS）effect of trace catechol was directly explored on water system.It was found that these MXene films possess very strong SERS effect for trace catechol in water.Even if the concentration of catechol is 5×10^-8 mol L^-1,we could still observe a significant Raman signals originated from catechol.In addition,these films possess high selectivity,excellent signal repeatability（RSD<5.86%,spot-to-spot）,high reproducibility（RSD<6.16%,batch-to-batch）and good stability.More interestingly,the aforementioned films possess excellent salt tolerance and are highly sensitive to trace catechol in seawater.The detection limit is low to 1×10^-7 mol L^-1 in seawater.Moreover,there exists a good linear relationship between Raman signal intensity and catechol concentration within a broad concentration range of catechol.Therefore,the above substrates are expected to be used for the qualitative and quantitative determination of trace catechol in seawater.These results imply that the as-prepared MXene films fill the gap of applying SERS means to timely monitoring catechol in seawater.