Direct conversion of waste tires into three-dimensional graphene

Approximately 1000 million used tires will emerge worldwide each year, and the quantity continually grows as the vehicle development. Numerous tires are inevitably discarded, and thus their disposal is a worldwide issue. Herein, we for the first time achieve to directly convert waste tires into 3D graphene through alkaline-assisted one-step pyrolysis process with no using any expensive chemical reagents and complex installations. By elevating the treatment temperature from conventional ∼800 °C to above 1000 °C, the generated potassium metal vapor will induce the carbon atom rearrangement, which facilitates the soft carbon components in the waste tire to convert into graphene-type structure. Our systematically study demonstrates the morphology evolution of waste tire from amorphous carbon nanospheres, monolithic carbon conglomeration, wrinkled graphene, and finally to vertical 3D graphene. The obtained 3D graphene exhibits a high electrical conductivity of 18.2 S cm−1, which is obviously two orders higher than the traditional active carbon. Profit from such a high conductivity and favorable hierarchical 3D graphene structure with rich porosity, the material can serve as a decent energy storage material. When used as a supercapacitor electrode, it exhibits excellent capacitive behaviors with both high rate performance and superstable cyclic life (retention of 95.9% after 10 000 cycles). This work not only propose a new protocol for high-value reuse of waste tires but also provides a potential low-cost feedstock for large scale production of graphene.