Mechanochemical synthesis of carbon from CO2: Mechanism for milling process-dependent morphology of carbon

Abstract

Facile, efficient, energy–saving and environmentally benign synthesis of carbon from CO2 is desirable and critical for the large–scale utilization of greenhouse gas and carbon materials. Herein, a green, energy–saving and facile route is provided to efficiently synthesize carbon with various morphology and porosity via mechanochemical reaction of CO2 with NaH. After 1 min ball milling, CO2 is converted into hierarchical porous carbon. The morphology and porosity of as–synthesized carbon is found to strongly depend on ball milling conditions. The gas blowing effect and self–template of product of Na2CO3 are responsible for the formation of hierarchical porous carbon. The buffering effect of Na2CO3 and pores in and between carbon particles in repeated ball milling process is revealed as the key factor in determining the morphology and porosity of carbon, resulting in the morphology and porosity of carbons associated with ball milling conditions. This study provides a new avenue for green and energy–saving synthesis of carbon and efficient utilization of greenhouse gases.