Reducing CO2 to dense nanoporous graphene by Mg/Zn for high power electrochemical capacitors

• We discovered that hot molten Zn/Mg mixture reduces atmospheric CO2 to dense nanoporous graphene.
• The nanoporous graphene exhibits high surface area, great conductivity and a high tap density.
• The property ensemble enables one of the best rate performances for electrochemical capacitors.

Converting CO2 to valuable materials is attractive. Herein, we report using simple metallothermic reactions to reduce atmospheric CO2 to dense nanoporous graphene. By using a Zn/Mg mixture as a reductant, the resulted nanoporous graphene exhibits highly desirable properties: high specific surface area of 1900 m2/g, a great conductivity of 1050 S/m and a tap density of 0.63 g/cm3, comparable to activated carbon. The nanoporous graphene contains a fine mesoporous structure constructed by curved few-layer graphene nanosheets. The unique property ensemble enables one of the best high-rate performances reported for electrochemical capacitors: a specific capacitance of ~170 F/g obtained at 2000 mV/s and 40 F/g at a frequency of 120 Hz. This simple fabricating strategy conceptually provides opportunities for materials scientists to design and prepare novel carbon materials with metallothermic reactions.

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