Carbon-supported platinum-lanthanum(Pt-Ln)intermetallic compound(IMC)nanoparticles with high activity and robust stability have been demonstrated as promising cathode catalysts for proton-exchange membrane fuel cells....Carbon-supported platinum-lanthanum(Pt-Ln)intermetallic compound(IMC)nanoparticles with high activity and robust stability have been demonstrated as promising cathode catalysts for proton-exchange membrane fuel cells.However,the preparation of Pt-Ln IMC catalysts needs high-temperature annealing treatment that inevitably causes nanoparticle sintering,resulting in significant reduction of the electrochemical surface area and mass-based activity.Here,we prepare small-sized M-doped Pt_(5)Ce(M=Ga,Cd,and Sb)IMCs catalysts via a low-melting-point metal doping strategy.We speculate that the doping of low-melting-point metals can facilitate the generation of vacancies in the crystal lattice through thermal activation and thus reduce the kinetic barriers for the formation of intermetallic Pt_(5)Ce catalysts.The prepared Ga-doped Pt_(5)Ce catalyst exhibits a higher electrochemical active surface area(81 m^(2)·gPt^(-1))and a larger mass activity(0.45 A·mgPt^(-1)at 0.9 V)over the undoped Pt_(5)Ce and commercial Pt/C catalysts.In the membrane electrode assembly test,the Ga-doped Pt_(5)Ce cathode delivers a power density of 0.98 W·cm^(-2)at 0.67 V,along with a voltage loss of only 27 mV at 0.8 A·cm^(-2)at the end of accelerated stability test.展开更多
Carbon supported Pt-based intermetallic compounds(IMCs)with high activity and durability are the most competitive cathode catalysts for the commercialization of proton exchange membrane fuel cells(PEMFCs).The synthesi...Carbon supported Pt-based intermetallic compounds(IMCs)with high activity and durability are the most competitive cathode catalysts for the commercialization of proton exchange membrane fuel cells(PEMFCs).The synthesis of Pt-based intermetallics with a good balance between small size and high metal loading remains challenging because of the high-temperature annealing that is generally required to form intermetallic phases.We developed a sodium thiosulfate-assisted impregnation strategy to synthesize small-sized and highly ordered PtM IMCs catalysts(M=Co,Fe,Ni)with high-Pt-content(up to 44.5 wt%).During the impregnation process,thiosulfate could reduce H_(2)PtCl6 to form uniformly dispersed Pt colloid on carbon supports,which in turn prevents the aggregation of Pt at the low-temperature annealing stage.Additionally,the strong interaction between Pt and S inhibits particle sintering,ensuring the formation of small-sized and uniform PtM intermetallic catalysts at the high-temperature annealing stage.The optimized intermetallic PtCo catalyst delivered a high mass activity of 0.72 A mgPt^(–1)and a large power performance of 1.17 W·cm^(–2)at 0.65 V under H_(2)-air conditions,along with 74%mass activity retention after the accelerated stress test.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22065016 and 22071225)the Plan for Anhui Major Provincial Science&Technology Project(Nos.202203a0520013 and 2021d05050006)the fellowship of China Postdoctoral Science Foundation(No.2022M712179).
文摘Carbon-supported platinum-lanthanum(Pt-Ln)intermetallic compound(IMC)nanoparticles with high activity and robust stability have been demonstrated as promising cathode catalysts for proton-exchange membrane fuel cells.However,the preparation of Pt-Ln IMC catalysts needs high-temperature annealing treatment that inevitably causes nanoparticle sintering,resulting in significant reduction of the electrochemical surface area and mass-based activity.Here,we prepare small-sized M-doped Pt_(5)Ce(M=Ga,Cd,and Sb)IMCs catalysts via a low-melting-point metal doping strategy.We speculate that the doping of low-melting-point metals can facilitate the generation of vacancies in the crystal lattice through thermal activation and thus reduce the kinetic barriers for the formation of intermetallic Pt_(5)Ce catalysts.The prepared Ga-doped Pt_(5)Ce catalyst exhibits a higher electrochemical active surface area(81 m^(2)·gPt^(-1))and a larger mass activity(0.45 A·mgPt^(-1)at 0.9 V)over the undoped Pt_(5)Ce and commercial Pt/C catalysts.In the membrane electrode assembly test,the Ga-doped Pt_(5)Ce cathode delivers a power density of 0.98 W·cm^(-2)at 0.67 V,along with a voltage loss of only 27 mV at 0.8 A·cm^(-2)at the end of accelerated stability test.
文摘Carbon supported Pt-based intermetallic compounds(IMCs)with high activity and durability are the most competitive cathode catalysts for the commercialization of proton exchange membrane fuel cells(PEMFCs).The synthesis of Pt-based intermetallics with a good balance between small size and high metal loading remains challenging because of the high-temperature annealing that is generally required to form intermetallic phases.We developed a sodium thiosulfate-assisted impregnation strategy to synthesize small-sized and highly ordered PtM IMCs catalysts(M=Co,Fe,Ni)with high-Pt-content(up to 44.5 wt%).During the impregnation process,thiosulfate could reduce H_(2)PtCl6 to form uniformly dispersed Pt colloid on carbon supports,which in turn prevents the aggregation of Pt at the low-temperature annealing stage.Additionally,the strong interaction between Pt and S inhibits particle sintering,ensuring the formation of small-sized and uniform PtM intermetallic catalysts at the high-temperature annealing stage.The optimized intermetallic PtCo catalyst delivered a high mass activity of 0.72 A mgPt^(–1)and a large power performance of 1.17 W·cm^(–2)at 0.65 V under H_(2)-air conditions,along with 74%mass activity retention after the accelerated stress test.
