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[Display omitted] • A two stage confinement strategy assisted facile synthesis of 5.3 nm highly ordered PtCoZn/NC. • PtCoZn/NC ordering and graphitization are promoted by regulating composition and calcination-time. • High intrinsic activity (2.8 mA cm-2 Pt) and slight E 1/2 loss (9 mV) in ADT were achieved by PtCoZn/NC. • It is evidenced weaker O binding and stronger Pt-Co/Zn bonding enhance activity and durability. • The ionomer-free and anti-sintering feature of carbon-walls also benefit the MEA performance. Intermetallic ordered PtCo is effective for high oxygen reduction reaction (ORR) activity and stability. However, preparing small-sized, highly ordered PtM alloys is still challenging. Herein, we report a controlled two-stage confinement strategy, in which highly ordered PtCoZn/NC nanoparticles of 5.3 nm size were prepared in a scalable process. The contradiction between the high ordering degree with the small particle size as well as the atomic migration with the space confinement was well resolved. An outstanding PEMFC performance was achieved for L1 0 -PtCoZn/NC with a high mass activity (MA) of 1.21 A/mg Pt at 0.9 V iR-free , 80.1 % MA retention after 30 k cycles in H 2 -O 2 operation, and a high mass-specific power density of 8.24 W mg-1 Pt in H 2 -Air operation with a slight loss of cell voltage@0.8 A cm−2 of 28 mV after 30 k cycles. The high performance can be ascribed to the high Pt area exposure, the enhanced Pt-Co coupling, and the prevented agglomeration in the mesoporous carbon wall. Overall, this strategy may contribute to the commercialization of fuel cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • We synthesized Au@PtNiAu concave octahedral core-shell nanocatalysts (Au@PtNiAu-COCS). • The mass activity of this catalyst is 11.22 times in ORR and 4.56 times in MOR than commercial Pt/C. • It exhibits a superior power density under fuel cell operation and better performance. • Its half-wave potential displacement after 30 k cycles is only 12 mV. • It retained the 78.8% of MA after 30 k cycles in ORR and lower CO oxidation overpotential in MOR. Despite the remarkable research efforts, the lack of ideal activity and state-of-the-art electrocatalysts remains a substantial challenge for the global application of fuel cell technology. Herein, is reported the synthesis of Au@PtNiAu concave octahedral core-shell nanocatalysts (Au@PtNiAu-COCS) via solvothermal synthesis modification and optimization approach. The special structure generating a large number of step atoms, enhancing the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) activity and stability. The superior ORR mass activity of the Au@PtNiAu-COCS is 11.22 times than the exhibited of Pt/C initially by Pt loading, and 5.11 times by Pt + Au loading. After 30 k cycles the mass activity remains 78.8% (8.83 times the initial Pt/C activity) and the half-wave potential only shifts 12 mV. Au@PtNiAu-COCS has superior half-cell activity and gives ideal membrane electrode assemblies. Furthermore, for MOR the Au@PtNiAu-COCS show enhanced anti-toxic (tolerant) ability in CO. This work provides a new strategy to develop core-shell structure nanomaterials for electrocatalysis. [ABSTRACT FROM AUTHOR]

The development of cost-effective and highly-efficient electro-catalysts is essential for the advancement of proton exchange membrane fuel cells (PEMFC). We present a novel nitrogen-sulphur co-doped carbon nanotubes-few layer graphene1D-2D hybrid support formed by partially exfoliating multiwall carbon nanotubes (PECNT), to improve interface bonding to catalyst nanoparticles. Detailed Raman spectroscopy and STEM-EDS analyses demonstrate that active sites on the co-doped hybrid support ensure both uniform distribution and improved bonding of the catalyst nanoparticles to the support. Electrochemical studies show that Pt nanoparticles decorated on nitrogen-sulphur co-doped PECNT (Pt/NS-PECNT) have higher electrochemical active surface area and mass activity accompanied by low H 2 O 2 formation and improved positive half-wave potential, as compared to those decorated on co-doped rGO-incorporated PECNT hybrid structure (Pt/NS-(rGO-PECNT)). Fuel cell measurements demonstrate a higher power density for our novel (Pt/NS-PECNT) electro-catalyst when compared to both Pt/NS-(rGO + PECNT), and commercial Pt/C electro-catalyst. We demonstrate in this work that the interconnectivity between Pt-nanoparticles and the dopant or defect sites on the support play a crucial role in enhancing the ORR activity, fuel cell performance, and durability of the catalyst. [ABSTRACT FROM AUTHOR]