Method for integrally forming graphene film (GF) of high specific surface area (SSA) by ultrafast ultraviolet (UV) laser processing

1. A method for integrally forming a graphene film (GF) of a high specific surface area (SSA) by ultrafast ultraviolet (UV) laser processing, comprising the following steps:

S1: selecting a carbon precursor material, wherein the carbon precursor material comprises a biomass/hydrogel composite;

S2: adding an activator solution to an inside of the carbon precursor material to obtain a composite of an activator uniformly loaded, the composite being of a gel form, and spreading the composite of the gel form on a flexible substrate to form a carbon precursor material layer;

S3: heating and drying the carbon precursor material layer obtained in S2 to obtain a composite film in which an activator crystal is loaded inside the carbon precursor material;

S4: in-situ processing the composite film obtained in S3 by an ultrafast UV laser to obtain an activated GF of a high SSA; and

S5: cleaning and drying the activated GF,

wherein in S2, the carbon precursor material layer has a thickness of no less than 30 μm; a mass ratio of the carbon precursor material to the activator is 2:(1.5-4);

progressive parallel scanning is conducted with the ultrafast UV laser at a scanning speed of 40 mm/s to 60 mm/s and a scanning pitch of 24 μm to 28 μm; a spot diameter of the ultrafast UV laser is 6 to 10 times the scanning pitch; and

the ultrafast UV laser has a wavelength of no more than 355 nm and a pulse width of less than 12 ps; and

in S1, the biomass/hydrogel composite is obtained by compounding a biomass of a hydrogel, wherein the biomass is one selected from the group consisting of lignin, cellulose, hemicellulose, and chitin and the hydrogel is one selected from the group consisting of gelatin, polyvinyl alcohol (PVA), and polyacrylamide (PAM).

2. The method according to claim 1 , wherein in S2, the activator is any one selected from the group consisting of potassium hydroxide, zinc chloride, sodium hydroxide, potassium carbonate, copper chloride, and phosphoric acid.

3. The method according to claim 1 , wherein in S2, the flexible substrate has a rough surface; or

a smooth surface of the flexible substrate is processed by a high-energy beam to form a microstructure array; or

a smooth surface of the flexible substrate is treated with plasma to form a superhydrophilic surface.

4. The method according to claim 1 , wherein in S3, the carbon precursor material layer is heated and dried on a heating plate or in a vacuum drying oven to allow crystallization in the activator solution, wherein the heating is conducted at 60° C. to 100° C. for 5 min to 30 min.

5. The method according to claim 1 , wherein the in-situ processing with the ultrafast UV laser is conducted in an air environment, a vacuum environment, an inert gas-protected environment, or an oxygen/inert gas mixed gas environment;

an inert gas is any one selected from the group consisting of nitrogen, argon, and a sulfur hexafluoride gas; and

in the oxygen/inert gas mixed gas environment, a mass ratio of oxygen to an inert gas is not higher than 0.25.

6. The method according to claim 1 , wherein in S5, the activated GF is soaked for 5 min to 20 min in a neutralization solution and warm deionized water at 60° C. to 70° C. successively, then soak-cleaned multiple times in cold deionized water until resulting cold deionized water is neutral, and then dried in a vacuum drying oven at a temperature of 40° C. to 60° C. and a relative vacuum degree of −90±2 kPa.