Preparation Of Au-pt Bimetallic Nanoparticles/Carbon Quantum Dots Composite And Their Application In Methanol Electrooxidation

Anode electro-catalyst is one of the most important parts in direct methanol fuel cell and nobal metal platinum is regarded as an ideal anode catalyst.However,the high cost,limited resource and low tolerance to poison effect limit its commercial application.In order to reduce the consumption of Pt content and strengthen the electrocatalytic activity of Pt-based anode electro-catalyst,Pt should be replaced by bimetal Au@Pt nanoparticles.Carbon quantum dots,a new class of carbon nanomaterials that have been received a great deal of attention owing to a number of advantageous characteristics,such as excellent conductivity,good water solubility,remarkable optical properties and simple synthesis process in the field of materials,chemistry,physics.Here,we are committed to develop novel carbon quantum dots/Au-Pt bimetal composite with excellent performance in terms of taking the advantages of both carbon quantum dots and Au-Pt bimetallic materials.In this paper,the novel electro-catalyst is fabricated by using gold,platimum and carbon quantum dots.The following research was carried out:?1?Two steps strategy is develop for the fabrication of Au@N-CQDs@Pt nanocomposites.First,the synthesis of N-CQDs was carried out through the hydrothermal method,and then Au@N-CQDs was synthesized by reducing HAuCl₄with N-CQDs.The remarkable advantage of the method here is no any stabilizer,reducing agent or surfactant agent involved.In order to obtain core-shell Au@N-CQDs@Pt nanoparticles,H₂PtCl₆ was put into the Au@N-CQDs colloid solution,and then ascorbic acid,function as reductant,was put into the mixture at ambient temperature.As resulting solution turned black,the Au@N-CQDs@Pt nanoparticles were obtained.The nanocomposites were characterized by UV-vis spectroscopy,transmission electron microscopy?TEM?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?and so on.Electrochemical measurements demonstrated the Au@N-CQDs@Pt exhibited excellent electrocatalytic activity toward methanol oxidation significantly attributed to the synergistic effect of carbon quantum dots,Au and Pt.When the AA reacting time was 45min,the prepared Au@N-CQDs@Pt had the best catalytic activity,which was 3.7 times than commercial Pt/C catalyst.?2?Based on the previous experiment,the Pt/N-CQDs was obtained by reducing H₂PtCl₆ with NaBH₄ in presence of N-CQDs.The Pt/N-CQDs and the synthesizedAu@N-CQDswerethenultrasonicallymixedtoform Au@N-CQDs-Pt/N-CQDs nanocomposites.The formed composites were characterized by transmission electron microscopy,X-ray diffraction,and X-ray photoelectron spectroscopy.The electrochemical activity of the modified electrode was investigated by cyclic voltammetry.It was found that the material has good catalytic activity for the electrocatalytic oxidation of methanol.The results show Au@N-CQDs-Pt/N-CQDs had much better catalytic activity,which was 2.26 times than Pt/N-CQDs.It is indicated that the addition of Au@N-CQDs can significantly improve the catalytic activity of Pt/N-CQDs on methanol oxidation.