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Transitional metal-nitrogen-carbon system is a promising candidate to replace the Pt-based electrocatalyst due to its superior activity, durability and cost effectiveness. In this study, we have designed a simple strategy to fabricate carbon nanotubes-supported binary-nitrogen-carbon catalyst via wet-chemical method. Palladium and transitional metals (M, i.e. manganese cobalt and copper) nanoparticles are anchored through four-nitrogen system onto carbon nanotubes (denoted as PdM-N4/CNTs). This material has been used as bifunctional electrocatalyst for electrochemical ethanol oxidation reaction and hydrogen evolution reaction for the first time. The N4-linked nanoparticles onto carbon nanotubes plays a crucial role in intrinsic catalytic activity for both reactions in 1 M KOH electrolyte. Among three PdM-N4/CNTs catalysts, the PdMn-N4/CNTs catalyst exhibits higher catalytic activity in terms of current density, mass activity and stability compared to the benchmark Pt/C. The robust electrocatalysis are inherited from the better attachment of PdMn through N4-system onto carbon nanotubes, comparatively smaller particles formation with better dispersion and higher electrical conductivity. [ABSTRACT FROM AUTHOR]

Replacement of precious platinum catalyst with efficient and cheap bifunctional alternatives would be significantly beneficial for electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) and the application of these catalysts in fuel cells is highly crucial. Despite numerous studies on electrocatalysts, the development of bifunctional electrocatalysts with comparatively better activity and low cost remains a big challenge. In this paper, we report a nanomaterial consisting of nanocactus-shaped Co 3 O 4 grown on carbon nanotubes (Co 3 O 4 /CNTs) and employed as a bifunctional electrocatalyst for the simultaneous catalysis on ORR, and OER. The Co 3 O 4 /CNTs exhibit superior catalytic activity toward ORR and OER with the smallest potential difference (0.72 V) between the [Formula: see text] (1.55 V) for OER and E 1/2 (0.83 V) for ORR. Thus, Co 3 O 4 /CNTs are promising high-performance and cost-effective bifunctional catalysts for ORR and OER because of their overall superior catalytic activity and stability compared with 20 wt% Pt/C and RuO 2 , respectively. The superior catalytic activity arises from the unique nanocactus-like structure of Co 3 O 4 and the synergetic effects of Co 3 O 4 and CNTs.