Ch3oh

Silver
nitrate (99.0%,
AgNO₃, Sigma-Aldrich), sodium borohydride (99%, NaBH₄, Sigma-Aldrich), ethyl alcohol (94.5%, C₂H₅OH, Daejung), chromium nitrate nonahydrate (99%, Cr(NO₃)₃·9H₂O, Sigma-Aldrich), terephthalic
acid (98%, C₈H₆O₄, Sigma-Aldrich), N,N-dimethylformamide (99.8%, C₃H₇NO, Daejung), methyl alcohol (99.5%, CH₃OH,
Daejung), and acetone (C₃H₆O, 99.8%, Daejung)
were purchased and used without further purification. Deionized water
(18.2 MΩ·cm at 25 °C) purified using a Merck Millipore
Direct Q3 UV Water Purification System was used for all washing and
aqueous solution preparation. All glassware was treated with aqua
regia (a mixture of HCl and HNO₃ with a volume ratio of
3:1), repeatedly washed with deionized water, and dried immediately
before use.

The aligned CNT sheets were synthesized via the FC-CVD method (Figure 1a). The mixture of
methanol (CH₃OH, Daejung Chemical, 99.8%) and n-hexane (C₆H₁₄, Daejung Chemical, 98.5%) in
9:1 vol % was used as a carbon source. Also, ferrocene (1 wt %, Fe(C₅H₅)₂, Sigma-Aldrich, 98%) and thiophene
(3 vol %, C₄H₄S, Sigma-Aldrich, ≥99%)
were added to the mixture as a catalyst and promoter, respectively.
The prepared source solution was injected into the furnace at 1300
°C by a syringe pump at a rate of 12 mL/h. Hydrogen (H₂) and argon (Ar) were used as the carrier gases with 110:1 (vol %).
The aerogel-like CNTs were synthesized and collected on a winder.
The continuously synthesized CNT aerogel was collected and densified
using acetone.

Chromium nitrate nonahydrate
(99%, Cr(NO₃)₃·9H₂O, Sigma-Aldrich),
2-aminoterephthalic acid (99%, C₈H₇NO₄, Alfa Aesar), sodium hydroxide (99.99%, NaOH, Sigma-Aldrich), 1%
graphene oxide aqueous solution (10 g/L, Grapheneall Co., Ltd.), methyl
alcohol (99.5%, CH₃OH, Daejung), N,N-dimethylformamide (>99.8%, HCON(CH₃)₂, Daejung), and ammonia gas (99.9995%, NH₃, Daesung
Industrial
Gases Co., Ltd.) were purchased and used without further purification.
Deionized water (18.2 MΩ·cm at 25 °C) purified by
a Merck Millipore Direct Q3 UV Water Purification System was used
for all washing and aqueous solution preparation. Autoclave Teflon
containers were treated with aqua regia (a mixture of HCl and HNO₃ with a volume ratio of 3:1) and 3 M NaOH repeatedly, washed
with deionized water, and dried immediately before use.