Graphene, preparation method thereof and supercapacitor electrode and supercapacitor containing the graphene

A method for preparing a mesoporous graphene, comprising the following steps:

• Step 1, mixing a magnesium powder with a magnesium oxide powder homogeneously to obtain a mixed powder, placing said mixed powder in a sealed pressure-resistant container, and embedding a tungsten coil in said mixed powder;
• Step 2, reducing pressure in said sealed pressure-resistant container to 2×10−4 Pa by using a molecular pump, and introducing carbon dioxide gas into said sealed pressure-resistant container until the pressure in said sealed pressure-resistant container is 0.125-10 MPa;
• Step 3, applying a direct current of 0.5-30 A to said tungsten coil by using a direct current power supply, for a period of 5-30 s, whereby a reaction between the magnesium powder and the carbon dioxide is initiated by heat generated from the tungsten coil, and after the reaction proceeding for 1-2 min, obtaining a black powder;
• Step 4, placing said black powder in a dilute acid solution, followed by standing for 6-48 h, then washing said black powder with deionized water by sucking filtration until the powder is neutral, thereby obtaining a filter cake, and freeze-drying said filter cake to obtain a mesoporous graphene powder.