Growth of Defect-Induced Carbon Nanotubes for Low-Temperature Fruit Monitoring Sensor

Round 1

Reviewer 1 Report

The manuscript “Growth of Defect-induced Carbon Nanotubes for Low Temperature fruit monitoring Sensor” reported a defect-induced carbon nanotube on Ni layer for ethylene detection at low temperature (30 °C). This study designed well and addressed various aspects, including the materials synthesis, sensing mechanism, materials characterization, experimental parameters optimization, etc. However, there were few issues need to be addressed.

• Please check on page 5 of 12, line 5. When Raman spectrum was carried out to justify the multilayer structure formation of CNTs. Please consider adding citation to the end of sentence. In the meantime, authors has claimed that G’/G=0.17 indicates the multilayer formation. Do you have more details regarding in what threshold the formation could be a monolayer?
• In the section 3.5, Sensing mechanism toward ethylene, there were potential reaction in between ethylene molecular with the CNTs, please give more detailed information to explain what type of reaction there were on the interface. For example, what product has formed after the electron transfer from ethylene to CNTs? Please be very careful when you claim there are electron transfer in between the two materials. Please do also consider the adsorption effects in between the CNTs and ethylene when you try to illustrate the potential sensing mechanism.
• Is the fabricated sensor sensitive to the humidity? I noticed you only used dry air to do such an experiment.
• What was the pressure when the ethylene tested?

Author Response

the response is attached 

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper reports the synthesis and gas sensing performance of carbon nanotubes. The experimental data and theoretical discussion are good. I think this paper can be published in this journal.

1. The microstructure of the nanotube can be investigated, such as TEM and HRTEM observation.
2. The selectivity of the sensor can be investigated.
3. The sensing mechanism can be given in a schematic illustration.
4. The sensing repeatability of the sensor for detecting rotten fruit can be demonstrated on different bananas. 

Author Response

The response is attached 

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript ”Growth of Defect-induced Carbon Nanotubes for Low Temperature fruit monitoring Sensor” by Nagih M. Shaalan et al. describes the behavior of CNT-based gas sensor operating at temperatures below 100 °C and exposed from 0.3 to 10 ppm of ethylene. The article is worded quite objectively and content is easy to understand. My comments are mainly focused to ensure a better comprehension and dissemination for the readers that may benefit from this paper and can be stated that the article can be published after mandatory revisions.

My suggestions and recommendations are:

1. Remove lines from 104 to 118 that seems to be remains of the Journal Author guide
2. Explain why you consider this type of gas sensors an electronic nose (no demonstration of an array of sensors working in parallel is presented) or remove this nomenclature from introduction and conclusions
3. In Figure 1 scratch is one of the steps. Explain it better in the text
4. Ensure that all y-axis units in graphs are within parenthesis
5. It would be very interesting to include a complementary graph in Figure 12 with the equivalent ethylene concentration deduced from the sensor response during the banana ripening measurement
6. For a proper comprehension of the ethylene sensing mechanism proposed in section 3.5. a scheme would be very illustrative

Author Response

The response is attached 

Author Response File: Author Response.pdf