▎ 摘　　要

NOVELTY - The process involves providing a porous graphene oxide film comprising a multilayer array of graphene oxide sheets. The graphene oxide film is subjected to a photo-reduction process. The reduced graphene oxide sheet having a pore of a different size is separated from a sheet overlapping by a different interlayer distance relative to a corresponding graphene oxide sheet in the graphene oxide film prior to the photo-reduction. USE - Process for preparing porous graphene-based film. ADVANTAGE - The process for preparing porous graphene-based film has the ability to accurately control the reduction process and hence the pore size and interlayer spacing in the porous graphene-based film for e.g. reduction of an oxygen containing functional group in a pore of a graphene oxide sheet and/or in between two or more graphene oxide sheets is selectively controlled by adjusting the radiation power. The higher the power of the beam, the higher the proportion of oxygen containing functional groups in the graphene oxide film that are reduced. The sieving characteristics of the resultant reduced graphene oxide film to be tuned within a large range are enabled. DETAILED DESCRIPTION - The oxygen containing functional group is situated in a pore of a graphene oxide sheet and in between two or more graphene oxide sheets is reduced to form a porous graphene- based film comprising one reduced graphene oxide sheet. The graphene oxide film is irradiated with a laser beam to reduce one or more oxygen containing functional groups. The graphene oxide film is irradiated with a laser beam selected from a continuous-wave (CW) laser beam and a pulsed laser beam. A selected zone of the porous graphene oxide film is irradiated by a laser beam to reduce an oxygen containing functional group situated in a pore of a graphene oxide sheet and in between two or more graphene oxide sheets in the selected zone and thereby alter the pore size and/or sheet interlayer distance in the selected zone by forming at least one reduced graphene oxide sheet in the selected zone. The irradiation parameters of the laser beam is controlled to irradiate a first zone of the graphene oxide film under a first condition and a second zone of the graphene oxide film under a second condition to form a porous graphene-based film having two different zones of different pore size and/or sheet interlayer distance. The porous graphene-based film is crosslinked. The porous graphene-based film is crosslinked with a polyol. The polyol is selected from the group consisting of ethylene glycol, 1,2-propylene glycol, butylene glycol, 1,6-hexalene glycol, neopentyl glycol, glycerol and pentaerythritol. The graphene oxide film comprises a crosslinking compound and irradiation of the graphene oxide film crosslinks the film and reduces at least one oxygen-containing functional group. The irradiation of the graphene oxide film is performed to selectively remove carbon atoms from the basal plane of a graphene oxide sheet to generate one or more defect openings in the plane of the sheet. The porous graphene-based film under conditions that selectively remove carbon atoms from the basal plane of a sheet in the graphene-based film is irradiated to generate one or more defect openings in the plane of the sheet. The graphene oxide film has a thickness of in a range of from about 30 nm to about 3 nm. The laser beam is emitted by an infrared (IR) laser. The passages have a diameter ranging in size from nm to micron are provided. The porous multi-zone graphene-based film comprises a reduced graphene oxide zone comprising porous reduced graphene oxide. INDEPENDENT CLAIMS are included for the following: (1) a multi-zone graphene-based film comprises two different reduced graphene oxide zones. The two different reduced graphene zones have a different porosity to one another. The different porosity in the different reduced graphene oxide zones is provided by pores in one or more sheets of a reduced graphene oxide zone being of a different size than that of pores in another reduced graphene oxide zone. The different porosity in the different reduced graphene oxide zones is provided by two or more sheets in a reduced graphene oxide being separated by an interlayer spacing that is different than that of sheets in another reduced graphene oxide zone. Each of the different reduced graphene oxide zones comprises a reduced graphene oxide sheet having one or more defect openings in the plane of the sheet. The defect openings in one reduced graphene oxide zone are of a different size to the defect openings in another reduced graphene oxide zone. The film is in the form of a 3D structure having multiple zones of different porosity. The different reduced graphene oxide zones comprise one or more passages extending through the zone. The passages in the different reduced graphene oxide zones are of a different size to one another. A multi-zone graphene-based film is crosslinked. The multi-zone graphene- based film is supported on a substrate; and (2) a method of removing a target solute from a solution comprising the step of filtering a solution comprising the target solute through a filtration membrane. The target solute is selectively retained by the membrane. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view illustrating the process for preparing a porous graphene-based reduced graphene oxide film with a laser beam.