Ultrasonication-assisted ultrafast preparation of multiwalled carbon nanotubes/Au/Co3O4 tubular hybrids as superior anode materials for oxygen evolution reaction

• An ultrasonic approach to synthesize CNTs-Au@Co3O4 tubular hybrids.
• The preparation process is simple, mild, green and ultrafast.
• The structure provides sufficient active centers and rapid mass/charge transport.
• Au NPs are uniformly dispersed and accelerate the formation of CoIV in OER.
• The electrocatalyst achieves ultrahigh activity and strong durability in OER.

Efficient and simple operation electrocatalysts for the oxygen evolution reaction (OER) are essential components of renewable energy technologies. Here, a novel, simple, and efficient routine is presented for the first time by constructing a high-efficiency anode catalyst for OER. With the aid of high intensity ultrasound, a uniformly loading, conductive multiwalled carbon nanotubes/metal/transition metal-oxide (CNTs-Au@Co3O4) tubular hybrids is synthesized. In alkaline media, the materials catalyze OER with an onset potential of 1.56 V vs. reversible hydrogen electrode (RHE) and overpotential only of 350 mV to achieve a stable current density of 10 mA cm−2 for at least 25 h. The unusual catalytic activity and stability is due to the following elements. Firstly, the tubular architecture not only provides sufficient active centers for OER, but also improves rapid mass/charge transport. Secondly, Co3O4 layer protects Au nanoparticles (NPs) against detachment. In addition, we also prove that the highest electronegativity metal Au accelerate the formation of catalytic active sites of CoIV species for OER. It is believed that this simple preparation method paves a way to fabricate a range of CNTs/metal/metal-oxide based composites as superior OER catalysts.

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