Waste-biomass tar functionalized carbon spheres with N/P Co-doping and hierarchical pores as sustainable low-cost energy storage materials

Biomass tar has exhibited promising potential for fabricating carbon-based functional materials. In this study, carbon materials with hierarchical pores, N/P co-doping, and oxygen-rich functional groups were prepared from glucose and biomass tar via a hydrothermal treatment combined with H3PO4 activation strategy and their electrochemical performances were evaluated. The results showed that the coating of tar inhibited agglomeration of carbon sphere derived from glucose and regulated its surface properties, resulting in hierarchical porous structure and surface functional groups. During thermal treatment, the resultant carbon materials were appropriately self-heteroatom doped by N and P from tar and H3PO4, respectively. Due to the unique structure, the specific capacitance of as-prepared carbon electrode was 199 F g−1. The symmetric TGC-600 capacitor showed excellent electrochemical properties with specific capacitance of 175 F g−1 and energy density of 6.1 Wh kg−1. Furthermore, TGC-600 capacitor showed superior cyclic stability, the capacitance retention was around 92% after 5000 runs. This study offered a green and low-cost utilization approach for biomass tar to prepare supercapacitor with excellent electrochemical performance.