In Situ Fabrication Of Pt-Based Alloys Embedded In Graphene Nanopore And Their Electrocatalytic Performance

Fuel cell is a promising energy system that can be used in fuel cell vehicles(FCV)and portable mobile devices because of its high energy conversion efficiency,virtually no pollution,and potential large-scale applications.However,fuel cells require a catalyst for oxygen reduction reaction(ORR).Traditionally,platinum(Pt)has been regarded as the best ORR catalyst.Unfortunately,limited resources and the high cost of Pt have also made the Pt-based catalysts the primary barrier to commercial mass market of fuel cells.Toward such a crucial background,the article have fabricated a special graphene hybird catalyst with Pt-based alloy embedded in N-doped graphene nanopores using a simple and practicable method.By taking sythesis condition such as: annealing teamperature and precursor into account,the article have investigated the influence of graphene nanopores on ORR systematically.The detailed contents of our work are listed as follow:(1)A novel PtCo alloy in situ etched and embedded in graphene nanopores(PtCo/NPG)as a high-performance catalyst for ORR was reported.Graphene nanopores were fabricated in situ while forming PtCo nanoparticles that were uniformly embedded in the graphene nanopores.Given the synergistic effect between PtCo alloy and nanopores,PtCo/NPG exhibited 11.5 times higher mass activity than that of the commercial Pt/C cathode electrocatalyst.This study showed that PtCo/NPG is a potential candidate for the next generation of Pt-based catalysts in fuel cells.(2)Based on our previous work,a new structured catalyst that porous PtFe nanoparticles was embedded in N-doped graphene nanopores was prepared successfully.The special ‘double porous' structure can not only expose active sites sufficiently,but also in favor of the diffusion of feedstock and products during electrochemical reaction,and further enhance the electrochemical performance.Result from these,the catalyst exhibited an excellent bifunctional catalytic performance for oxygen reduction reaction and hydrogen evolution reaction with both activity and stability more superior than commeriacal Pt/C catalyst.(3)A unique nitrogen rich sandwich-architectured catalyst was successfully fabricated.Physical characterizations revealed the presence of both Co2 P and Cox N lattice structures in one nanoparticle,most of the nanoparticles were encapsulated in nitrogen doped carbon shell and uniformly dispersed on the graphene sheets.It is confirmed that the catalyst can behave as a highly efficient bifunctional electrocatalyst for both ORR and OER with superior positive onset potentials,large kinetic current density and outstanding stability.The electrocatalysis performance of the catalyst is among the one of the most active bifunctional catalysts.Such impressive performance originating from positive synergistic effect of the CoNP and nitrogen-rich nanostructure.