Preparation Of Graphene/platinum Nanoparticles By Gamma Irradiation And Their Catalytic Performance For Oxygen Reduction

Graphene-based platinum nanoparticles(Pt NPs)composites are widely used in the field of oxygen reduction catalysts as their excellent catalytic properties.However,the preparation of graphene oxide-based platinum nanoparticle composites still has many problems,such as complicated processes,serious pollution and large energy consumption.Gamma irradiation technology of⁶⁰Co not only has the characteristics of uniformity,high efficiency and low pollution,but also can crush the size of particles at a higher radiation dose.According to our previous studies,gamma rays can also induce the growth of small interlayer molecules and peel off graphite oxide,and meantime,the size of the platinum nanoparticles can be effectively controlled by the interlayer limiting effect of graphite oxide.Therefore,gamma irradiation is expected to be an ideal preparation method for graphene-based platinum nanoparticle composites.In this work,graphene oxide with different degrees of peeling was obtained through the different ultrasonic time for graphite oxide,and then combined with the action of reducing free radicals in solution induced by high energy?rays and the fragmentation effect to Pt NPs,graphene oxide/Pt NPs with different morphologies were prepared;Urea was used as the nitrogen source in the?irradiation system to prepare the nitrogen-doped graphene oxide-based Pt NPs composites.It is worth noting that the platinum nanoparticles on the prepared composite material have a polygonal angular structure,which is beneficial to the catalytic activity to oxygen reduction reaction;Nitrogen-doped graphene oxide/Pt NPs composites were prepared with different?irradiation dose,and the structural evolution of Pt NPs under?-ray irradiation was studied.Results show that the interlayer distance of graphene oxide has an important effect on the dispersion,particle size of Pt NPs and the performance of the sample,with a best initial potential and half-wave potential of 0.874 V and 0.784 V,respectively,and a limiting current density of 6.48 m A·cm^-2;Urea doping provides a high content of pyridine nitrogen and angular Pt NPs on the sample,which increases the active sites for catalytic activity.The optimal initial and half-wave potentials are0.906 V and 0.783 V,respectively,with the limiting current density of 6.69 m A·cm^-2when the molar ratio of urea to Pt is 20:1;Under?-ray irradiation,Pt NPs are induced to grow and then fragmentation.When the dose is 60 k Gy,the sample has the best initial potential and the half-wave potential of 0.908 V and 0.821 V,respectively,and the limiting current density of 6.65 m A·cm^-2.Therefore,the graphene/Pt NPs composites prepared by?-ray irradiation have excellent oxygen reduction catalytic performance,which provides a certain theoretical basis and technical support for the preparation of catalysts by?-ray irradiation.