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To explore cheap alternatives for platinum electrocatalysts, many strategies have been widely studied. And Pd is regarded as a ideal alternative catalyst due to its high stability and catalytic activity. In this work, we designed a facile method to prepare a highly efficient electrocatalyst in which ultrafine Pd nanoparticles are embedded into N-doped porous carbon nanosheets for oxygen reduction reaction (ORR) in alkaline and acid media. A series of products with different Pd quantities were in situ prepared in the absence of additional reductant and capping agents by varying the addition of PdCl2, while the morphology and the structural features of products through X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) and BET measurements show that Pd nanoparticles are embedded into N-doped porous carbon nanosheets. Obviously, the sample of Pd-NCs-3 demonstrate the best electrocatalytic activity and remarkable long-term stability among the series, which is superior to that of commercial Pd/C and comparable to that of commercial Pt/C for ORR in alkaline and acid media. The results provides a novel strategy for the rational development of cheap alternatives for platinum electrocatalysts.

The development of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts with high performance and excellent stability is meaningful for fuel cells. Herein, two-dimensional closely packed amide polyphthalocyanine...

A defect-rich interconnected hierarchical threedimensional Fe and N co-doped graphene has been prepared by a facile synthesis with poly (2,5-benzimidazole) (ABPBI) as nitrogen and carbon sources and CaCO 3 as the template. ABPBI possesses abundant nitrogen, and pyrolysis of ABPBI is helpful to form graphene structure. CaCO 3 and its decomposition products CO 2 can promote the formation of interconnected hierarchical porous three-dimensional graphene, which possesses more defects and exposed active sites. Benefiting from the defective catalysis mechanism, rich defect catalysts are applied as electrode materials to enhance the catalytic performance for oxygen reduction reaction (ORR). Electrochemically, the half-wave potential (E 1/2) of Fe-3D-NG#800 is 0.84 V (vs. RHE), and the accelerated durability tests shows the E 1/2 of Fe-3D-NG#800 shifted by a 21 mV drop after cyclic voltammetry scanning for 5000 cycles. Therefore, Fe-3D-NG#800 has excellent activity and durability than 20 wt % Pt/C.