Preparation Of Metal Nanoparticles/MXene Composites And Study On Catalytic Reduction Of 4-nitrophenol

4-Nitrophenol is one of the refractory organic pollutants,and its reduction product p-aminophenol is an important chemical intermediate.The catalytic reduction method is an effective way to convert 4-nitrophenol into 4-aminophenol,among which nano-precious metal catalysts with high specific surface area are often used for the catalytic reduction of4-nitrophenol.However,due to its high specific surface energy,it is prone to agglomeration,which reduces the active sites of the catalyst and reduces the stability and activity of the catalyst.Therefore,it is necessary to find a suitable carrier to support the noble metal catalyst to prevent its agglomeration,improve its stability,and maximize the activity of the catalyst.The main research results are as follows:（1）A goldnanocompositecatalystwassynthesizedusing polydiallyldimethylammonium chloride（PDDA）and two-dimensional titanium carbide（MXene）as stabilizer and carrier,respectively.PDDA can change the surface charge properties of MXene,provide stable grafting sites for gold nanoparticles（Au NPs）,prevent their agglomeration,and accelerate the catalytic reduction process.The rate constant of catalytic reduction of 4-nitrophenol is as high as 2.653×10^-2S^-1.An efficient and stable catalyst is provided for the catalytic reduction of p-nitrophenol to 4-aminophenol.（2）A silver nanoparticle（Ag NPs）/titanium carbide（MXene）composite hydrogel catalyst was prepared using polyacrylamide（PAM）as the cross-linked network.PAM,Ag NPs,and MXene act as adsorbents,electron transfer mediators,and catalytically active species,respectively.Through the synergistic effect of these three components,the electron transfer ability and adsorption ability of the catalyst are improved,and the catalytic activity is enhanced.The catalytic rate constant k and conversion frequency TOF are as high as 8.333min^-1and 25.17 min^-1,respectively,which are better than most of the catalysts reported so far.In addition,this composite hydrogel catalyst with foam structure is easy to separate and recycle,and has excellent reusability.