High performance zinc-air batteries (ZABs) demand highly active bifunctional catalysts for both oxygen reduction reaction (ORR) and oxygen evolution reactions (OER). Herein, we report a FeCo-Co bifunctional catalyst with well-engineered interfaces between FeCo nanoalloy and metallic Co, via an alloying-degree control strategy. The FeCo-Co architecture can be obtained by manipulating the alloying degree through proper introduction of Fe, while the stacked carbon nanosheet morphology inherited from the precursor can fully expose the active sites facilitating the ion transfer. FeCo-Co interface structure enables FeCo@Co/N-C-8 catalyst to exhibit an excellent half-wave potential (0.870 V) superior to Pt/C (0.846 V) for ORR and suppressed overpotential (312 mV) than IrO 2 (321 mV) for OER. The as prepared rechargeable ZAB based on FeCo@Co/N-C-8 catalyst displays an excellent peak power density of 148 mW cm −2 and an ultrahigh open circuit voltage of 1.52 V. This research provides an innovative technique in construction of bifunctional catalysts for ZABs through alloying degree control strategies.
Hucheng Zhang,Yingying Shang,Jing Zhao,Jianji Wang
This work developed a facile colloidal route to synthesize BH4–-capped PdxAgy nanoparticles (NPs) in water using the reducing ionic liquids of [Cnmim]BH4, and the resulting NPs were prone to form the nanocomposites with [amim]+-modified reduced graphene (RG). The removal of the metal-free inorganic ions of BH4– can create the profoundly exposed interfaces on the PdxAgy NPs during the electrooxidation, and favor the ethanol oxidation reaction (EOR) in lowering energy barrier. The counterions of [Cnmim]+ can gather ethanol, OH– ions, and the reaction intermediates on catalysts, and synergistically interact with RG to facilitate the charge transfer in nanocomposites. The interface-modified RG nanosheets can effectively segregate the PdxAgy NPs from aggregation during the EOR. Along with the small size of 4.7 nm, the high alloying degree of 60.2%, the large electrochemical active surface area of 64.1 m2 g–1, and the great peak current density of 1501 mA cm–2 mg–1, Pd1Ag2@[C2mim]BH4-amimRG nanocomposite exhibits the low oxidation potentials, strong poison resistance, and stable catalytic activity for EOR in alkaline media, and hence can be employed as a promising anodic catalyst in ethanol fuel cells.
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