▎ 摘　　要

NOVELTY - A unitary graphene layer (112) or graphene single crystal containing closely packed and chemically bonded parallel graphene oxide planes is produced by preparing graphene oxide gel having graphene oxide molecules dispersed in fluid medium, where graphene oxide gel is optically transparent or translucent; depositing a layer of graphene oxide gel onto a surface of supporting substrate to form deposited graphene oxide gel; partially or completely removing fluid medium from deposited graphene oxide gel layer to form graphene oxide layer; and heat-treating graphene oxide layer at greater than or equal to 500 degrees C. USE - Production of unitary graphene layer or graphene single crystal containing closely packed and chemically bonded parallel graphene oxide planes for use as heat spreader in microelectronic device, such as mobile phone, notebook computer, electronic-book (e-book), and tablet; flexible device; LED; power tool; computer CPU; and power electronics. ADVANTAGE - The graphene monolith exhibits a combination of exceptional thermal conductivity, electrical conductivity, mechanical strength, surface smoothness, surface hardness, and scratch resistance unmatched by any thin-film material of comparable thickness range. DETAILED DESCRIPTION - A unitary graphene layer (112) or graphene single crystal containing closely packed and chemically bonded parallel graphene oxide planes is produced by preparing graphene oxide gel having graphene oxide molecules dispersed in fluid medium, where graphene oxide gel is optically transparent or translucent; depositing a layer of graphene oxide gel onto a surface of supporting substrate to form deposited graphene oxide gel; partially or completely removing fluid medium from deposited graphene oxide gel layer to form graphene oxide layer; and heat-treating graphene oxide layer to form unitary graphene layer or graphene single crystal at greater than or equal to 500 degrees C. The unitary graphene layer or graphene single crystal has inter plane spacing of 0.335-0.4 nm, thickness of greater than or equal to 10 nm, electrical conductivity of greater than or equal to 1500 S/cm, thermal conductivity of greater than or equal to 600 W/mK, physical density of greater than or equal to 1.8 g/cm3, oxygen content of 0.01-10 wt.%, and average mis-orientation angle between 2 graphene oxide planes of less than or equal to 10 degrees . DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the processes for producing graphite or graphene oxide paper, mat, film, and membrane of simply aggregated flakes/platelets. Flakes of natural graphite (100) Graphite intercalation compounds (102) Exfoliated graphite flakes or worms (104) Expanded graphite (108) Unitary graphene layer (112)