Abstract
Carbon nanotubes (CNTs) have attracted a lot of attention due to their unique electrical, thermal and mechanical properties [1-3]. CNTs are also highly suitable to achieve multi-functional materials when combined with a range of nanoparticles (NPs)[4-6].
In this work, CNT macroscopic ribbon structures are synthesized using the floating catalyst chemical vapor deposition (FC-CVD) approach, using Iron as a catalyst, sulfur to limit the iron growth and to enhance the growth rate of the CNTs and methane as a carbon precursor [7].
Plasma-induced non-equilibrium electrochemistry (PiNE) was then used to synthesize NiO QDs and subsequently spray coated them onto CNT ribbons. The PiNE process used a Ni foil as the anode and a nickel tube as the cathode powered by direct current supply (45 min, 2 kV, 5mA). The NiO QDs exhibited a diameter of 3nm and were spray coated onto the CNTs which had been pre-treated with HNO3 to remove the Fe catalysts. The CNT-NiO QDs composite were tested for H2 generation with promising results.
As the two-step process highlighted limitations in the NP loading, a second approach was devised, developed and tested for high loading with Zn-based NPs. An RF helium microplasma reactor was integrated in-line with the CNT synthesis set-up to produce CNT-NPs in one-step process. Transmission and scanning electron microscopy confirmed the presence of ZnO NPs with a good coverage of the CNT ribbons. X-ray photoelectron spectroscopy shows that up to 40% of Zn can be loaded on the CNT ribbons, which represents a substantial improvement towards energy storage applications.
References
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Figure 1