Upcycling of refinery solid waste by chemical activation: Fabrication of molybdenum sulfide/hierarchical porous carbon composites for highly stable supercapacitor

Refinery solid waste (RSW) is a typical hazardous waste due to its large amount of production and high toxicity and it is important to reutilize the RSW. However, it is still challenge for efficient recycling the RSW due to its complex composition. Herein, we present an effective route to realize the upcycling of the RSW with the MoS2 nanosheet/coke hierarchical structure, which serves as a sustainable electrode material for the fabrication of supercapacitors. The RSW is used as the raw material to fabricate molybdenum sulfide/hierarchical porous carbon (MoSx/HPC) through the carbonization and activation method by using KOH as the chemical activator and KCl as the auxiliary template. The obtained results indicate the MoSx/HPC that prepared with the raw/KOH/ KCl mass ratio of 1:3:3 possesses high specific surface area (2908.9 m2g- 1) and hierarchical micro-mesoporous structure. The stable structure of highly dispersed MoSx and HPC further supports the high cycle stability of MoSx/HPC-based supercapacitors. The MoSx/HPC-133-based supercapacitors exhibit high capacitance of 349.7 Fg- 1 at 1 Ag-1 in 6 M KOH and high cycle stability of 95.8 % after 10,000 charge-discharge cycles at 20 Ag-1. In addition, the fabricated supercapacitors show high power density of 450.03 Wkg- 1 and energy density of 33.99 Whkg- 1 in 1 M Na2SO4 aqueous electrolyte, indicating outstanding electrochemical activity. This work not only provides an effective and facile strategy to fabricate hierarchical MoSx/HPC composite that can be used for the fabrication of high-performance supercapacitors, but also brings new insight to understand the potential advantages of RSW to fabricate sustainable materials.