Morphology investigation on direct growth ultra-long CNTs by chemical vapour deposition method for high performance HER applications

Carbon nanotube (CNT) is prepared by chemical vapor deposition method and their electrochemical behaviors for instance oxygen evolution (OER) and hydrogen evolution (HER) reaction have been successfully studied. In recent times, Pt-free electrocatalysts have been greatly attractive in electrochemical hydrogen evolution re-actions for the replacement of fossil fuels and development of sustainable energy carriers. Chemical vapor deposition method was used as an efficient way to synthesize CNTs directly. The as prepared free-standing and multifunctional CNT electrodes are used for overall water splitting applications. In this work, we have designed CNT as electrode material as well as current collector using Ni-foil and Ni-foam substrate and their fundamental characterizations confirm the structural, morphological behaviors of CNTs. Moreover, the well-ordered growth of CNT was obtained in Ni-foam CNTs 1 and 2, whereas in the Ni foil CNTs 1 and 2 less growth of CNT and amorphous carbon sponge was exceeded, which was further confirmed by the SEM images. The achieved elec-trochemical HER results displayed that the Ni-foam-CNT-2 exhibited lower overpotential, smallest Tafel slope and lower resistance value of 110 mV, 240 mV/dec and 0.24 omega respectively. Moreover, Ni-foam-CNT-2 revealed excellent stability with 86.6 % retention over 20 h. Hence, it is one of the cost-effective and reliable materials for electrochemical hydrogen evolution reaction.

Automated summary

In this study, carbon nanotube (CNT) electrodes with excellent electrochemical performance were prepared using chemical vapor deposition method. The results showed that CNTs synthesized on Ni-foam substrate exhibited lower overpotential and resistance, and demonstrated efficient catalytic activity for hydrogen evolution reaction. This method offers a cost-effective and reliable approach for electrochemical water splitting.