We would like to provide the following responses to the concerns raised about the methodology and the reliability of results in a letter to the Editor by Rawal et al. [1] commenting on our article [2]: (1)The fiber volume fraction of the carbon nanotubes, as calculated from the porosities, is not possible experimentally or theoretically. A: The BPs were prepared by using a filtration method. The carbon nanotubes were firstly functionalized with chemical groups and then dispersed in solvent with a polymer dispersant. After filtration, the original BPs were very dense and nearly voidless. If we want to obtain porous BPs, we must treat the BPs by using the correct method, so the experiments are different from theoretical analysis.(2)There is no direct relationship between tensile strength and porosity, but the article claimed that tensile strength and modulus of buckypapers (BPs) were reduced with the increase in porosity. A: The CNTs in the BPs were connected by van der Waals forces. With the porosity increasing in the BPs, the contact points and the number of CNTs in the BPs will inevitably drop. The relationship between tensile strength and porosity is an experimental result.(3)The letter suggested that the authors derived incorrect porosities by wrongly applying the Barrett-Joyner-Halenda (BJH) method, which might be resolved by showing the primary N2 adsorption-desorption isotherm data. A: In the BPs, the pores can be divided into closed, semiopen, and open; the BJH adsorption-desorption method can be used to measure the semiopen and open pores. This experiment was carried out according to the BET method, MBET was used to calculate the surface area and specific surface area, and BJH was used to calculate the porosity and pores size.(4)The article concludes from the Raman ratio that the “integrity of the CNTs was not destroyed after oxidation treatment,” but single values are of limited use in CNT Raman spectroscopy. The Raman spectrum of the untreated sample is not given. A: References [3–6] can explain this.(5)Figure 6a showing TEM cannot represent BPs, because BPs cannot be directly imaged by TEM. The sample is typically sonicated in a solvent, and nanotubes are drop-casted onto a TEM grid, which completely deconstructs the BP. The article does not give details of the sample preparation for TEM. A: The TEM image was provided in response to a reviewer request. The BPs were obtained from the CNT suspension, and the sample of TEM was also directly taken from the CNT suspension.(6)The conduction paths in Figure 6 are possible, but there are other possibilities that the article did not consider. A: We just proposed preliminary guesswork, expecting more detailed and excellent works in the near future.
We regret that the raw data are unavailable, because the student who had the data graduated and is unreachable.
Conflicts of Interest
The authors declare that there is no conflict of interests regarding the publication of this paper.