Synthesis
of electrocatalysts for oxygen reduction reaction (ORR)
with not only prominent electrocatalytic performance but also a low
amount of Pt is the urgent challenge in the popularization of fuel
cells. In this work, through a facile synthetic strategy of spray
dehydration on a solid surface and annealing process, we demonstrate
the first manufacture of quaternary structurally ordered PtM3 (M = transition metal) intermetallic nanoparticles (NPs), Pt(Fe,
Co, Ni)3, in order to lower the content of Pt. The atomic
contents of Pt, Fe, Co, and Ni are equal and the chemical structure
of Pt(Fe, Co, Ni)3 is a cubic L12-ordered structure.
L12-Pt(Fe, Co, Ni)3/C electrocatalysts exhibit
enhanced electrocatalytic performance toward ORR with mass activity
(MA) 6.6 times higher than the commercial Pt/C and a minimal loss
of 17% in MA and 1.5% loss in specific activity (SA) after 10 000
potential cycles at 0.9 V. Furthermore, the stability behavior is
confirmed to be attributed to the coaction of particle sizes and the
ordering effect. Compared with traditional Pt-based electrocatalysts
in the stoichiometric forms of Pt3M and PtM, L12-Pt(Fe, Co, Ni)3 intermetallic NPs exhibit excellent performance
and higher cost effectiveness. Moreover, this work also proposes a
facile and effective synthetic strategy for manufacturing multicomponent
Pt-based electrocatalysts for ORR.
Constructing robust and cost-effective Pt-based electrocatalysts with an easily operated strategy remains a crucial obstacle to fuel cell applications. Conventional Pt-based catalysts suffer from high Pt content and an arduous synthetic process. Herein, through the spray dehydration method and annealing treatment, facile producible synthesis of a small-sized (5.2 nm) low-Pt (10.5 wt %) ordered PtCo 3 /C catalyst (O-PtCo 3 /C) for oxygen reduction reaction is reported. The fast spray evaporation rate contributes to small size and uniform nucleation of nanoparticles (NPs) on carbon support. O-PtCo 3 /C-600 exhibits efficient electrocatalytic performance with mass activity (MA) 6.0-fold and specific activity 3.9-fold higher than commercial Pt/C. The ordered chemical structure generates superior stability with merely 3.5% decay in MA after 10,000 potential cycles. Density functional theory calculations reveal that the enhanced catalytic performance originates from rational modification of d-band through strain and ordering effect and accompanying weaker adsorption of intermediate OH. This work highlights the potentials of low-Pt PtM 3 -type ordered NPs for prospective fuel cell cathodic catalysis. The proposed facile and practical synthetic strategy also shows promising prospects for preparing effective Pt-based electrocatalysts.
The energy storage mechanism of hybrid supercapacitors originates mainly from Faradaic charge transfer generated on/near the surface of Faradaic pseudocapacitive materials. Therefore, the development of electrode materials with superior electron collection efficiency and energy storage capacity is urgently needed for supercapacitor applications. Herein, we design and synthesize battery-like Mn−Co oxide/rGO hybrid nanostructures via a facile twostep process. By introducing graphene, the structural properties of Mn−Co oxide (MnCoO) are effectively modified. In addition, benefiting from the Schottky barrier caused by the difference in work functions, free electrons are trapped and accumulated at the Fermi level, enabling Mn−Co oxide to obtain superior electron accumulation effect. The fabricated hybrid electrode exhibits enhanced energy storage performances, with ultrahigh specific capacitance of 2749 F g −1 (381.8 mAh g −1 ) and remarkable cycling durability of 95.7% retention over 8000 cycles at 10 A g −1 . When fabricated as an asymmetric supercapacitor (ASC), an excellent energy density of 35.5 Wh kg −1 at 1008.2 W kg −1 can be delivered for the MnCoO-rGO/NF//rGO/NF device. This study can offer guidance for constructing high-performance supercapacitors through interfacial electronic structure design.
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