Method for preparing graphene by using two-dimensional confined space between the layers of inorganic layered materials

A preparation method for graphene, comprising the following steps:

• (1) mix a soluble salt of a divalent metal ion M2+, a soluble salt of a trivalent metal ion M′3+, a soluble salt of a chain alkyl anion A− and a carbon source molecule C and dissolve them in deionized and CO2-eliminated water to prepare a mixed salt solution;
• mix the mixed salt solution with an alkali solution under nitrogen protection and subject them to reaction and crystallization at 60° C. to 80° C. for 6 to 10 hours under nitrogen, filter the suspension obtained thereafter and wash the filter cake with deionized water until the pH of the filtrate is 7 to 7.5, and then dry the filter cake at 50° C. to 60° C. for 6 to 12 hours to obtain layered double hydroxides with an intercalated structure having a general chemical structure of:
• [M2+1-xM′3+x(OH)2]x+A−x.αC.βH2O
• wherein, x is 0.2-0.33, α is 0.2-6.6, and β is 0.3-3;
• (2) under an inert atmosphere or a reducing atmosphere, calcinate the layered double hydroxides with an intercalated structure to provide a calcinated product at a calcination temperature of 700° C. to 950° C. for a period of time of 0.5 to 3 hours;
• (3) add the calcinated product into a hydrochloric acid solution with a concentration of 5 wt % for ultrasonic treatment, and separate the solution by centrifugation and wash the precipitate obtained by centrifugation with deionized water until the pH of the filtrate is 6.5 to 7 to obtain the graphene.