Electrical Utilizations of Air Gap Region Formed on Superhydrophobic Silicone Rubber in NaCl Aqueous Solution

Round 1

Reviewer 1 Report

The author has demonstrated a superhydrophobic silicone rubber and displayed the electric voltage generation with metal needles in a NaCl solution droplet. However, there are some issues to be addressed prior to be accepted. 

1. The author claimed that the electric voltage was successfully generated between 2 wires in the air gap. However, the function of the air gap is unclear according to the present result. So the comparing experiment in the air gap-free condition need to be conducted and the mechanism should be further discussed. 

2. I think the mechanism of the electricity generation is the same as the classic voltaic cell actually. Therefore, the statement of "a new energy havsesting method" should be avoided. 

Author Response

Dear Reviewer#1:

Thank you very much for your kind review. According to your indications, we revised our manuscript as follows and all revised parts are indicated in red in the revised version:

1. The author claimed that the electric voltage was successfully generated between 2 wires in the air gap. However, the function of the air gap is unclear according to the present result. So the comparing experiment in the air gap-free condition need to be conducted and the mechanism should be further discussed.

Thank you very much. We have been checked that a pair of metal needles are kept approximately 3 mm apart and is inserted in 3 wt% NaCl aqueous solution on a nonirradiated silicone rubber, which is an air gap-free condition. At that time, the electric current flowed under the electric field of approximately 5 V/mm.

The manuscript has been corrected. Please confirm p.5, L201-L202 in revised manuscript

2. I think the mechanism of the electricity generation is the same as the classic voltaic cell actually. Therefore, the statement of "a new energy harvesting method" should be avoided.

Thank you very much. We removed ‘a new energy harvesting method’ in Abstract, Section 3.3, and Conclusion parts.

The manuscript has been corrected. Please confirm p.1, L20, p.5, L236-L237, and p.7, L298 in revised manuscript.

Thank you very much for your kind and valuable suggestions.

Sincerely,

Masayuki Okoshi

Reviewer 2 Report

Well written short article on the possibility of hydrogen production from sea water of hydrogen and energy harvesting powering small devices (such as IoT devices). The modifies a silicone rubber surface by using a ArF excimer laser to great defects which are hydrophobic.The air gap can be increased by introduction of air using a syringe. By submersion of the rubber, air droplets appear in created surface defects. First electrolysis of water is achieved by the placing electrodes inside the air gap and applying a small voltage (2-5V). Second a small droplet of NaCl is added inside the air gap and Al and Cu wires are put in the droplet to obtain a small galvanic cell for low power devices.

General remarks and questions

The article is interesting, the results are promising and the subject its well in the scope of this journal

There is no other comments or questions because it only needs minor corrections to the English text.

Author Response

Dear Reviewer#2:

Thank you very much for your kind review and understanding.

I checked the spelling of the entire manuscript. Thank you very much.

Sincerely,

Masayuki Okoshi

Round 2

Reviewer 1 Report

I aggree with the publication of this paper.