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CONSPECTUS:The content of carbon dioxide (CO 2 ) in the atmosphere has been continuously growing and threatens the global environment by contributing to the greenhouse effect. The conversion of CO 2 directly into value-added chemicals could not only reduce CO 2 emission but also make valuable use of the waste gas. However, achieving a highly efficient CO 2 conversion with high product selectivity and low energy cost remains a great challenge.Graphene, one of the most important engineering materials with a wide range of applications, is generally synthesized with valuable hydrocarbons as carbon sources. Producing versatile graphene materials directly from CO 2 is intriguing and of profound meaning. Furthermore, it is of critical importance to produce 3D-structured graphene materials, which can avoid the restacking of the graphene sheets and thus keep the graphene properties for practical applications. Alkali-metal-based exothermic reactions with inorganic carbon compounds, which have been discovered by our group since 2013, offer ideal solutions for efficient CO 2 utilization and cost-effective 3D graphene production. In the reactions, alkali metal salts formed simultaneously with the graphenization of CO 2 and served as in situ templates for creating the splendid microscale 3D structured graphene materials, which could hardly be achieved using other methods. Meanwhile, the etching effect of CO 2 molecules can realize controlled engineering of unique surface porous structures of the formed 3D graphene. Accordingly, diverse 3D graphene materials featuring fascinating properties that are desired for energy-related and environmental applications can be facilely obtained by tuning the conditions for the reactions of CO 2 with alkali metals. This Account provides an overview of the 3D graphene materials from the reduction of CO 2 via the state-of-the-art alkali-metalchemistry-based strategy. After an emphasis on the significance of the CO 2 -to-graphene conversion process, the alkali-metal-based chemistry for CO 2 conversion is introduced by delineating the thermodynamics of the reactions between CO 2 and alkali metals and the forming mechanism of the 3D-structured graphene materials as well as the carbon etching effect of CO 2 . Subsequently, as typical examples, 3D cauliflower-fungus-like graphene, 3D crape myrtle flower-like graphene and mesochannel carbon nanowalls, 3D honeycomb-like structured graphene, and 3D surface-microporous graphene are specifically discussed in terms of their synthesis processes, structural characteristics, and reaction-condition-dependent properties. Furthermore, the great promise of these CO 2derived graphene materials for application in solar cells, supercapacitors, batteries, and environmental remediation are demonstrated. Finally, the challenges remaining in this area and the directions for its future development are addressed.
