Tremendous efforts have been paid to tackle our energy crisis and environmental issues. CO2 as main source for the greenhouse effect, is very abundant in nature and can be used as feedstock to prepare value-added carbon materials via the electrochemical reduction. By carefully manipulating electrolysis current density, electrolyte composition, electrode materials and temperature, various functional carbon materials, including carbon nanotubes (CNTs), graphene, graphite, nanodiamonds, etc., could be readily generated with high Faraday Efficiency. The obtained materials exhibit excellented performances in energy applications like batteries and supercapacitors. Electrochemical reduction of CO2 provides a promising pathway for CO2 capture and conversion and creates materials suitable for high energy power/density devices.