▎ 摘　　要

NOVELTY - A cryogenic iron-doped graphene material is prepared by mixing concentrated sulfuric acid and sodium nitrite in flask, vigorously stirring, completely dissolving, adding graphite, slowly adding potassium permanganate, ice bathing, reacting, slowly adding water, and hydrogen peroxide, centrifuging, discarding supernatant, washing with diluted hydrochloric acid, centrifuging, oven drying, sonicating, centrifuging, reacting guanidine phosphate with graphene oxide dispersion liquid , and doping with iron salt. USE - Method for preparing cryogenic nitrogen-doped graphene material (claimed). DETAILED DESCRIPTION - A cryogenic iron-doped graphene material is prepared by mixing 17 mL concentrated sulfuric acid and 0.37 g sodium nitrite in flask, vigorously stirring for 10 minutes, completely dissolving, adding 0.5 g graphite, slowly adding 2.5 g potassium permanganate at less than or equal to 20 degrees C, ice bathing at 35 degrees C, reacting for 3 hours, slowly adding 125 mL water, and 2 mL hydrogen peroxide to obtain bright yellow precipitate, centrifuging at speed of 15000 revolutions/minute (rpm) for 15 minutes, discarding supernatant, washing with diluted hydrochloric acid at volume ratio of 1:5-10, centrifuging, oven drying for 48 hours under vacuum pressure, sonicating to obtain 0.5 mg/mL crude graphene oxide dispersion solution, centrifuging at speed of 10000 rpm for 15 minutes to remove precipitate and to obtain graphene oxide dispersion liquid, reacting guanidine phosphate with graphene oxide dispersion liquid at mass ratio of 1:8 at low temperature, preferably 20-30 degrees C, and doping with iron salt.