▎ 摘　　要

NOVELTY - Synthesizing (M1) pristine graphene quantum dots (GQD), comprises: providing a catalyst loaded substrate in a reactor, where the catalyst comprises a transition metal nanoparticle, a transition metal oxide, a metal alloy, or a metal hydroxide; maintaining the reactor at a first temperature of 1000-1200 degrees C and inert atmosphere comprising argon and/or nitrogen; and passing a hydrocarbon carrier gas at a flow rate of 40-60 SCCM over the catalyst loaded substrate to form GQD on the substrate, where the carrier gas comprises methane, ethane, liquefied petroleum gas, ethylene, acetylene, hexane, benzene, xylene and carbon monoxide. USE - The methods are useful for synthesizing pristine GQD and heteroatom doped GQD (all claimed) which are used in battery, fuel cell, biosensors, or strain sensors. ADVANTAGE - The methods: provide GQDs that has purity of better than 99%, preferably better than 99.8%; are free of catalyst; are cost-effective; are not using strong acids, and hazardous chemicals; utilize nanosized graphite that shows excellent properties of graphene, like large surface area, high carrier transport mobility, superior mechanical flexibility, photoluminescence, biocompatibility, low toxicity and excellent thermal and chemical stability; and provide GQDs that exhibit capacities of 400-500 mAhg-1 in a current density range of 0.05-1.5 Ag-1 for lithium ion anode and 100-200 mAhg-1 in a current density range of 0.05-2 Ag-1, exhibit excellent retention capacity at high current densities specific capacity of 1000 to 400 mAhg-1 is achieved in a range of 25-30 cycles for lithium ion battery, has cycling efficiencies of 95-98 % after 160 cycle number for lithium ion battery anode, and exhibit a number of desirable properties when implemented as electrode materials within batteries, including high specific capacity, high efficiency, long cycle life, high rate capability, and high chemical stability. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) a pristine GQD electrode material having a primary C(002) X-ray peak at 25.3 degrees 2 theta using copper K- alpha radiation, where the reversible specific capacity for the GQD is 400-500 mAh/g in a voltage range of 2.5-3 V for lithium anode, rate capability for the GQD is 1.5 A/g within 25-30 cycles for lithium anode and 1-2 A/g within 60-90 cycles for sodium anode and cycling efficiencies for the GQD is 75-80% at 0.05 A/g and 160 cycles for lithium anode; (2) synthesizing (M2) heteroatom doped GQD, comprising providing a mixture comprising graphite oxide and a heteroatom precursor in a reactor, where the heteroatom precursor comprises a nitrogen precursor (N-GQD), a boron precursor (B-GQD), and a phosphorus precursor (P-GQD), and the weight ratio of graphite oxide to heteroatom precursor is 1:4-4:1, flushing the reactor with an inert gas, where the inert gas is argon, introducing hydrogen gas in the reactor at a flow rate of 40-60 SCCM and annealing the mixture at a temperature of 200-500 degrees C in the presence of hydrogen gas to form the GQD; and (3) a heteroatom doped GQD electrode material, where the heteroatom is 10-20 wt.%, the pore size of GQD is 9-12 nm, the reversible specific capacity of GQD is 800-1000 mAh/g at a current density of 0.05 A/g in a voltage range of 2.5-3 V for lithium anode, rate capability of GQD is 1.5 A/g within 25-30 cycles for lithium anode and 1-2 A/g within 60-90 cycles for sodium anode and cycling efficiency of GQD is 60-80% at 160 cycles for lithium ion battery anode and 40-60% at 500 cycles for sodium ion battery anode.