Reduced graphene oxide film comprising a stack of rgo layers and its applications

A reduced graphene oxide (rGO) film having a total thickness from 20 nm to 5 micrometer, which comprises a stack of rGO layers comprising flakes, wherein a distance between two consecutive layers is from 0.2 to 0.7 nm, wherein the reduced graphene oxide (rGO) film is obtainable by a process which comprises the following steps:

• i) filtering a graphene oxide (GO) solution through a porous membrane thereby forming a GO film on a membrane top, wherein the graphene oxide (GO) solution is and aqueous solution, concentration of graphene oxide (GO) in the solution is from 0.001 to 5 mg/mL, and the volume filtered is from 5 to 1000 mL;
• ii) transferring the GO film from the membrane onto a sacrificial substrate, whereby the GO film is placed between the membrane at the top and the sacrificial substrate at the bottom;
• iii) removing the membrane, whereby the GO film remains attached onto the sacrificial substrate;
• iv) hydrothermally reducing the GO film to form a reduced GO material (rGO) at a temperature from 100 to 240° C., under a pressure from 105 to 4·108 Pa, for a time period from 1 min to 24 h, in the presence of water;
• and
• v) detaching the rGO material from the sacrificial substrate.