Fig. 1. A schematic representation showing the process of decoration of CNTs with tenorite nanoparticles. Blue spheres: CuAc; black spheres: CuO.

Fig. 2. SEM images of (a) MWCNTs decorated with CuO after three microwave treatments (CuAc loading 47.4 wt%) at low magnification, and (b and c) enlarged sections of image (a) showing individual nanoparticles of CuO.

Fig. 3. SEM images of (a) MWCNTs decorated with CuO after three microwave treatments (47.4 wt% CuAc initial loading) at low magnification, (b) enlarged section of image (a) with a tenorite nanoparticle. (c) EDX map superimposed on SEM image (b) showing the distribution of carbon, copper, oxygen, iron and indium, (d) EDX spectrum for the framed area in image (b), and (e-g) EDX individual maps for the carbon, copper, and oxygen, respectively.

Fig. 4. TEM images of tenorite nanoparticles decorating MWCNTs from (a) 9.1 wt% and (b) 47.4 wt% CuAc initial loading. Inset, higher magnification image of the CuO nanoparticle.

Fig. 5. Amount of copper acetate remaining unconverted on MWCNTs after an increasing number of 1-min microwave treatments. Comparison between two different initial loadings of CuAc: diamonds 47.4 wt%, squares 9.1 wt%.

Fig. 6. XRD patterns of MWCNTs with 47.4 wt% (red) and without (black) added copper acetate, after three microwave treatments. Miller indices refer to CuO (red) and MWCNTs (black) reflections.

Fig. 7. Copper loading in MWCNT samples measured using EDX plotted against the amount of copper from CuAc used during preparation (Table 1). Black circles and bars correspond to before microwave treatment, whilst red circles and bars are after three microwave treatments. The range bars represent the upper and lower limits of the spread of data. Each analysis is expressed as the average of three probed areas.

Fig. 8. (a) Representative Cu(2p) peaks from 90 wt% added CuAc sample after three microwave treatments, with fittings. (b) Representative C(1 s) peak from 30 wt% added CuAc sample after three microwave treatments with fitting.

Fig. 9. Copper loading in MWCNT samples measured using EDX (black circles) and XPS (red circles) after three microwave treatments plotted against the amount of copper from CuAc used during preparation (Table 1). For EDX, the range bars represent the upper and lower limits of the spread of data from at least three measurements. For XPS, one region scan was taken for each sample.

Fig. 10. TGA of pure copper acetate (black line), tenorite-decorated MWCNT samples after three microwave treatments (orange, green, and blue lines), and as received MWCNTs (red line).

Fig. 11. Copper loading in MWCNT samples measured using TGA after three microwave treatments plotted against the amount of copper from CuAc used during preparation (Table 1). The dashed diagonal line represents the expected copper loading when the only process occurring while microwaving is the conversion of CuAc to tenorite, without loss of carbon.