Free-standing carbon nanotubes as non-metal electrocatalyst for oxygen evolution reaction in water splitting

Free-standing carbon nanotubes as non-metal electrocatalyst for oxygen evolution reaction in water splitting

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Abstract and figures:

Oxygen evolution reaction (OER) has significant impact on the overall electrochemical water splitting. We introduce, for the first time, a facile approach towards the fabrication of versatile electrode composed of free-standing multiwalled carbon nanotubes (MWCNTs) as electrocatalyst for the water splitting reaction. Directly extracted MWCNTs as sheets from vertically grown arrays transferred over the glass substrate, are used without any post treatment as a working electrode for OER. Onset potential of 1.60 V was achieved for MWCNTs which is significantly reduced as compared to platinum based metal electrode (1.72 V) with excellent current density. No surface modification, metal-free nature, flexibility and low cost with excellent catalytic activity proved this material as a promising candidate for the replacement of metal based electrodes in electrochemical water splitting.

SUBJECT: Carbon nanotube sheets, Electrode fabrication, Electrocatalyst, Oxygen evolution reaction, Water splitting

 

Fig. 1. Schematic illustration of water splitting for the oxygen evolution reaction using MWCNTs.

Fig. 2. (a) Optical image of WMCNTs sheets extracted from vertical arrays and (b) MWCNTs as a sheet over a flexible plastic substrate.
 

Fig. 4. I-V curves for the different sheets of MWCNTs.

 

Fig. 5. a) LSVs of MWCNTs recorded in 3.0 M NaOH electrolyte with 10 mV/s scan rate, b) LSVs of MWCNTs recorded in 3.0 M NaOH and 0.1 M NaOH electrolyte with 10 mV/s scan rate, c) Repeating LSV of MWCNT-4 recorded in 3.0 M NaOH electrolyte with 10 mV/s scan (d) current profile of the electrode composed of MWCNTs for the period of 2000 s.

Table 1. LSV parameters comparison of different sheets of MWCNTs with Pt.

MWCNTs Sheet no. Sheet resistance (Ω/□) Onset potential (V) Current density (mAcm−2)
3 355 1.63 0.45
4 329 1.60 0.89
5 299 1.63 0.89
Pt 0.001 1.72 0.90

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