Preparation Of Silver Nanoparticles Supported Two-dimensional Materials By One-pot Method And Their Applications

Two-dimensional nanomaterials have the advantages of planar structure of atomic thin layer,adjustable band gap range and high specific surface area,which have great potential applications in electronic devices,surface-reinforced Raman,catalysis and other fields.Combining two-dimensional materials with metal nanoparticles or nanowires can enhance its performance in functional devices.Silver nanoparticles(Ag NPs)have excellent electrical conductivity and good light transmittance and flexure flexibility due to the nanometer size effect.The two-step method is usually used to composite two-dimensional materials with AGNPs.Firstly,Ag NPs are prepared by polyol method.Secondly,two-dimensional materials are prepared by liquid-phase stripping method.Finally they are physically mixed evenly.These steps are relatively complicated and the nanoparticles in the resulting composite materials are easy to fall off.This paper proposes a gentle and simple preparation method of Ag NPs/two-dimensional material composite material,using natural flake graphite and molybdenum disulfide powder as raw materials,and simultaneously realizes direct liquid phase exfoliation of two-dimensional material and in-situ synthesis of Ag NPs,and discusses the prepared composite material Applications.The main research includes:(1)Using natural flake graphite and silver nitrate as raw materials,N-methylpyrrolidone(NMP)as dispersant,sodium citrate as reducing agent of silver nitrate and stabilizer of graphene stripping,Ag NPs/graphene composite material is prepared by low speed mechanical stirring and ultrasonic action,and is applied to flexible strain sensor.The mechanical stirring speed(1000³000 r/min),ultrasonic time(1³ h)and the mass ratio of natural flake graphite to silver nitrate(1:2.5;1:2;1:1;2:1)on the morphology and size of the generated Ag NPs and the effect of graphene stripping.Experiments show that with the increase of the mechanical stirring speed,the thickness of the graphene sheet becomes thinner and the gauge factor(GF)of the sensor can reach up to 659.This is because when thicker graphene is used to make the sensor,the graphene sheet packing tightly in the conductive network will result in greater lap resistance,which will reduce the sensitivity of the sensor.With the increase of ultrasonic time,the GF of the sensor first increases and then decreases.When the ultrasound time is 1.5 h,the GF reaches299.This is because the thickness of the graphene sheet is getting thinner and the lateral size is getting smaller and smaller.As a result,the lap resistance first becomes larger and then becomes smaller.With the increase of the mass ratio of natural flake graphite to silver nitrate,the GF of the sensor first increases and then decreases.At 1:1,the GF reaches 431.This is because with the increase of Ag NPs,it is within a single graphene sheet.As well as providing an outer conductive path between different graphene sheets;as the mass ratio of AgNO₃ to natural flake graphite increases,the high concentration of Ag NPs loading will cause the conductive network to be covered by a large number of silver nanoparticles and cause a short circuit,which leads to the sensor GF reduce.(2)Based on the influence of the thickness of the graphene sheet and the particle size of Ag NPs on the sensor GF,the cyclic stability of the sensor under the condition of 2% strain for1000 cycles and the bending model under the condition of ±0.2% strain are investigated.The performance test,the damping exercise performance test fixed on the scale,and the application in the human throat muscles and forearm movement.The results show that the flexible stress sensor made of Ag NPs/graphene has good cycle stability and maintains excellent performance under the bending model.It shows good stability to ruler of damping vibration response and can accurately measures the change of the human body muscle activity,which has a broad application prospect in the field of artificial intelligence.(3)Using molybdenum disulfide and silver nitrate as raw materials,N-methyl pyrrolidone as dispersant,sodium citrate as reducing agent of silver nitrate.Ag NPs/molybdenum disulfide composites are prepared by low speed mechanical stirring stripping and ultrasonic reaction.The Ag NPs/molybdenum disulfide composite material is prepared as surface-enhanced raman scattering(SERS)substrate.Malachite green is used as the molecule to be tested.The effects of mechanical stirring speed(1000³000 r/min),ultrasonic time(1³h),and the mass ratio of silver nitrate to molybdenum disulfide(1:1⁵:1)on the substrate reinforcement factors are investigated by response surface analysis.Experiments show that the basal enhancement factor can reach 1779.90.With a concentration of malachite green as low as10-8 mol/L,a characteristic peak at 1175 cm-1 can still be observed,indicating that the substrate has good sensitivity.The linear relationship between the concentration of malachite green and the logarithm of the surface enhancement factor(EF)can be used as a standard for judging the concentration of unknown malachite green solutions,which makes the Ag NPs/MoS₂ substrate great potential in the practical application of malachite green detection.