The present invention discloses a layer-number-controllable graphene derived from natural biomass and a preparation method thereof. The preparation method includes pulverizing 1-100 g of biomass to obtain a 50- to 300-mesh biomass scrap, and drying the biomass scrap at 60-100° C. to obtain a biomass precursor; mixing the biomass precursor with a Bronsted acid solution in a solid-liquid ratio of 0.1:10 to 2:100 g/mL, conducting sealing after discharging oxygen and introducing nitrogen, and then conducting heating for a reaction at 75-95° C. for 1-6 hours to obtain a graphene suspension; and conducting post-treatment on the graphene suspension to obtain a stable graphene dispersion, and then drying the stable graphene dispersion to obtain a graphene powder, where the post-treatment includes one or more of filtration washing, dialysis or ultrasonic treatment. According to the preparation method, the layer-number-controllable graphene is prepared by a mild chemical strategy at relatively low temperature with the biomass having high selectivity as a carbon source. The present invention further provides a layer-number-controllable graphene prepared by the method.

The present invention discloses a layer-number-controllable graphene derived from natural biomass and a preparation method thereof. The preparation method includes pulverizing 1-100 g of biomass to obtain a 50- to 300-mesh biomass scrap, and drying the biomass scrap at 60-100° C. to obtain a biomass precursor; mixing the biomass precursor with a Bronsted acid solution in a solid-liquid ratio of 0.1:10 to 2:100 g/mL, conducting sealing after discharging oxygen and introducing nitrogen, and then conducting heating for a reaction at 75-95° C. for 1-6 hours to obtain a graphene suspension; and conducting post-treatment on the graphene suspension to obtain a stable graphene dispersion, and then drying the stable graphene dispersion to obtain a graphene powder, where the post-treatment includes one or more of filtration washing, dialysis or ultrasonic treatment. According to the preparation method, the layer-number-controllable graphene is prepared by a mild chemical strategy at relatively low temperature with the biomass having high selectivity as a carbon source. The present invention further provides a layer-number-controllable graphene prepared by the method.

Provided is a method of producing isolated graphene sheets directly from a biomass, the method including: (A) providing a biomass in a liquid state, solution state, solid state, or semi-solid state; (B) heat treating the biomass and, concurrently or sequentially, using chemical or mechanical means to form graphene domains dispersed in a disordered matrix of carbon or hydrocarbon molecules, wherein the graphene domains are each composed of from 1 to 30 planes of hexagonal carbon atoms or fused aromatic rings and, in the situations wherein there are 2-30 planes in a graphene domain, having an inter-graphene space between two planes of hexagonal carbon atoms or fused aromatic rings no less than 0.4 nm; and (C) separating and isolating these planes of hexagonal carbon atoms or fused aromatic rings to recover graphene sheets from said disordered matrix.

Provided is a method of producing isolated graphene sheets directly from a biomass, the method including: (A) providing a biomass in a liquid state, solution state, solid state, or semi-solid state; (B) heat treating the biomass and, concurrently or sequentially, using chemical or mechanical means to form graphene domains dispersed in a disordered matrix of carbon or hydrocarbon molecules, wherein the graphene domains are each composed of from 1 to 30 planes of hexagonal carbon atoms or fused aromatic rings and, in the situations wherein there are 2-30 planes in a graphene domain, having an inter-graphene space between two planes of hexagonal carbon atoms or fused aromatic rings no less than 0.4 nm; and (C) separating and isolating these planes of hexagonal carbon atoms or fused aromatic rings to recover graphene sheets from said disordered matrix.

The invention discloses a method for preparing graphene by mechanical exfoliation and application thereof. The method includes the following steps of: (1) dispersing graphite raw material in a foaming agent aqueous solution to obtain a graphite pre-dispersing solution; and (2) subjecting the graphite pre-dispersing solution to milling, washing with water, and centrifugal classification, to obtain the graphene; wherein the foaming agent aqueous solution includes the following components: sodium alpha-olefin sulfonate, sodium alcohol ether sulphate, diethanolamine coconut fatty acid, polyethylene glycol, and water. In the invention, the foaming agent produce a large amount of stable and fine foam in a closed milling cavity, which can produce jostle effect, support the graphite, and increase the contact area between the graphite and the milling medium, so as to achieve good exfoliation effect.

The invention discloses a method for preparing graphene by mechanical exfoliation and application thereof. The method includes the following steps of: (1) dispersing graphite raw material in a foaming agent aqueous solution to obtain a graphite pre-dispersing solution; and (2) subjecting the graphite pre-dispersing solution to milling, washing with water, and centrifugal classification, to obtain the graphene; wherein the foaming agent aqueous solution includes the following components: sodium alpha-olefin sulfonate, sodium alcohol ether sulphate, diethanolamine coconut fatty acid, polyethylene glycol, and water. In the invention, the foaming agent produce a large amount of stable and fine foam in a closed milling cavity, which can produce jostle effect, support the graphite, and increase the contact area between the graphite and the milling medium, so as to achieve good exfoliation effect.

Ultrafast flash Joule heating synthesis methods and systems, and more particularly, ultrafast synthesis methods to recover metal from ores, fly ash, and bauxite residue (red mud).

Ultrafast flash Joule heating synthesis methods and systems, and more particularly, ultrafast synthesis methods to recover metal from ores, fly ash, and bauxite residue (red mud).

Provided are graphene nanosheets having a polyaromatic hydrocarbon concentration of less than about 0.7% by weight and a tap density of less than about 0.08 g/cm.sup.3, as measured by ASTM B527-15 standard. The graphene nanosheets also have a specific surface area (B.E.T.) greater than about 250 m.sup.2/g. Also provided are processes for producing graphene nanosheets as well as for removing polyaromatic hydrocarbons from graphene nanosheets, comprising heating said graphene nanosheets under oxidative atmosphere, at a temperature of at least about 200° C.

Provided are graphene nanosheets having a polyaromatic hydrocarbon concentration of less than about 0.7% by weight and a tap density of less than about 0.08 g/cm.sup.3, as measured by ASTM B527-15 standard. The graphene nanosheets also have a specific surface area (B.E.T.) greater than about 250 m.sup.2/g. Also provided are processes for producing graphene nanosheets as well as for removing polyaromatic hydrocarbons from graphene nanosheets, comprising heating said graphene nanosheets under oxidative atmosphere, at a temperature of at least about 200° C.