The morphology and size of Pt-based bimetallic alloys are known to determine their electrocatalytic performance in reactions relevant to fuel cells.Here,we report a general approach for preparing Pt-M(M=Fe,Co and Ni)b...The morphology and size of Pt-based bimetallic alloys are known to determine their electrocatalytic performance in reactions relevant to fuel cells.Here,we report a general approach for preparing Pt-M(M=Fe,Co and Ni)bimetallic nano-branched structure(NBs)by a simple high temperature solution-phase synthesis.As-prepared Pt-M NBs show a polycrystalline structure and are rich in steps and kinks on the surface,which promote them favorable bifunctional catalytic properties in acidic electrolytes,specifically in terms of the oxygen reduction reaction(ORR)and methanol oxidation reaction(MOR).Specially,Pt-Co NBs/C catalyst shows 6.1 and 5.3 times higher in specific activity(SA)and mass activity(MA)for ORR than state-of-the-art commercial Pt/C catalysts,respectively.Moreover,it exhibits a loss of 4.0%in SA and 14.4%in MA after 10,000 cycles of accelerated durability tests(ADTs)compared with the initial activities.In addition,we also confirmed the superior MOR activity of Pt-Co NBs/C catalyst in acidic electrolytes.For Pt-M NBs with other alloying metals,the ORR and MOR activities are both higher than commercial catalysts and are in the sequence of Pt-Co/C>Pt-Fe/C>Pt-Ni/C>commercial Pt/C(or PtRu/C).The improved activities and durability can benefit from the morphological and compositional effects.This synthesis approach may be applied to develop bifunctional catalysts with enhanced ORR and MOR properties for future fuel cells designs.展开更多
The ordered Pt-based intermetallic nanoparticles(NPs)with small size show superior magnetic or catalytic properties,but the synthesis of these NPs still remains a great challenge due to the requirement of high tempera...The ordered Pt-based intermetallic nanoparticles(NPs)with small size show superior magnetic or catalytic properties,but the synthesis of these NPs still remains a great challenge due to the requirement of high temperature annealing for the formation of the ordered phase,which usually leads to sintering of the NPs.Here,we report a simple approach to directly synthesize monodisperse ordered L1_(0)-FePt NPs with average size 10.7 nm without further annealing or doping the third metal atoms,in which hexadecyltrimethylammonium chloride(CTAC)was found to be the key inducing agent for the thermodynamic growth of the Fe and Pt atoms into the ordered intermetallic structure in the synthetic process.In particular,10.7 nm L1_(0)-FePt NPs synthesized by the proper amount of CTAC show a coercivity of 3.15 kOe and saturation magnetization of 45 emu/g at room temperature.The current CTAC-assisted synthetic strategy makes it possible to deeply understand the formation of the ordered Pt-based intermetallic NP in solution phase synthesis.展开更多
基金This work was supported by the National Natural Science Foundation of China(Nos.51571072 and 51871078)Heilongjiang Science Foundation(No.E2018028)the China Scholarship Council,and the NSF MRSEC Program(DMR-14-19807).
文摘The morphology and size of Pt-based bimetallic alloys are known to determine their electrocatalytic performance in reactions relevant to fuel cells.Here,we report a general approach for preparing Pt-M(M=Fe,Co and Ni)bimetallic nano-branched structure(NBs)by a simple high temperature solution-phase synthesis.As-prepared Pt-M NBs show a polycrystalline structure and are rich in steps and kinks on the surface,which promote them favorable bifunctional catalytic properties in acidic electrolytes,specifically in terms of the oxygen reduction reaction(ORR)and methanol oxidation reaction(MOR).Specially,Pt-Co NBs/C catalyst shows 6.1 and 5.3 times higher in specific activity(SA)and mass activity(MA)for ORR than state-of-the-art commercial Pt/C catalysts,respectively.Moreover,it exhibits a loss of 4.0%in SA and 14.4%in MA after 10,000 cycles of accelerated durability tests(ADTs)compared with the initial activities.In addition,we also confirmed the superior MOR activity of Pt-Co NBs/C catalyst in acidic electrolytes.For Pt-M NBs with other alloying metals,the ORR and MOR activities are both higher than commercial catalysts and are in the sequence of Pt-Co/C>Pt-Fe/C>Pt-Ni/C>commercial Pt/C(or PtRu/C).The improved activities and durability can benefit from the morphological and compositional effects.This synthesis approach may be applied to develop bifunctional catalysts with enhanced ORR and MOR properties for future fuel cells designs.
基金supported by the National Natural Science Foundation of China under Grant(Nos.51871078,51631001 and 51590882)the National Key R&D Program of China(No.2016YFA0200102)Heilongjiang Science Foundation(No.E2018028).
文摘The ordered Pt-based intermetallic nanoparticles(NPs)with small size show superior magnetic or catalytic properties,but the synthesis of these NPs still remains a great challenge due to the requirement of high temperature annealing for the formation of the ordered phase,which usually leads to sintering of the NPs.Here,we report a simple approach to directly synthesize monodisperse ordered L1_(0)-FePt NPs with average size 10.7 nm without further annealing or doping the third metal atoms,in which hexadecyltrimethylammonium chloride(CTAC)was found to be the key inducing agent for the thermodynamic growth of the Fe and Pt atoms into the ordered intermetallic structure in the synthetic process.In particular,10.7 nm L1_(0)-FePt NPs synthesized by the proper amount of CTAC show a coercivity of 3.15 kOe and saturation magnetization of 45 emu/g at room temperature.The current CTAC-assisted synthetic strategy makes it possible to deeply understand the formation of the ordered Pt-based intermetallic NP in solution phase synthesis.