▎ 摘　　要

NOVELTY - Preparing catalyst comprises e.g. (i) taking expanded graphite as carbon source to obtain graphene oxide, (ii) adding graphene oxide prepared in step (i) into water and ultrasonically dispersing to obtain graphene oxide suspension, (iii) adding doped nitrogen source into graphene oxide suspension, dissolving to obtain mixed solution of graphene oxide and doped nitrogen source, (iv) setting temperature of mixed solution obtained in step (iii), setting hydrothermal reaction pressure and time, (v) soaking nitrogen-doped graphene hydrogel in water and adding ethanol. USE - The catalyst is useful for synergistic degradation of phenol by adsorption-catalytic oxidation; and in treating phenol-containing wastewater (all claimed). ADVANTAGE - The method has simple preparation, high catalytic efficiency, reduces energy consumption and phenol degradation rate reaches to 100 %. DETAILED DESCRIPTION - Preparing catalyst comprises (i) taking expanded graphite as carbon source to obtain graphene oxide, (ii) adding graphene oxide prepared in step (i) into water and ultrasonically dispersing to obtain graphene oxide suspension, (iii) adding doped nitrogen source into graphene oxide suspension and dissolving to obtain mixed solution of graphene oxide and doped nitrogen source, (iv) setting temperature of mixed solution obtained in step (iii), setting hydrothermal reaction pressure and time to obtain nitrogen-doped graphene hydrogel, (v) soaking nitrogen-doped graphene hydrogel prepared in step (iv) in water for period of time, setting time interval to replace water, adding ethanol in last change of water and soaking for some time, and (vi) pre-freezing nitrogen-doped graphene hydrogel immersed in step (v) and vacuum freeze-drying to obtain nitrogen-doped graphene airgel material i.e. catalyst. An INDEPENDENT CLAIM is also included for nitrogen-doped graphene airgel material is obtained by above method.