Fluorine-assisted asphalts waste carbonization to Ni-F-C electrocatalyst by mechanochemistry for efficient oxygen evolution

Abstract

Low-cost Ni-F-C electrocatalysts were gram-scale synthesized through mechanochemical synthesis accompanied by asphalt and e-waste polytetrafluoroethylene (PTFE) upgrading. The high-value utilization of bulk industrial solid waste and the design of high-performance oxygen evolution electrocatalyst hold immense importance for sustainable environment and energy economy. The overpotential at 10 mA cm−2 (1 M KOH) for the optimized Ni-F-C catalyst was low as 269 mV. First, PTFE as a pore-forming agent generated plenty of pores inside the Ni-F-C catalyst (promoting mass transfer and surface wettability). Second, the structural self-reconstruction caused by fluorine migration made the electrode surface undergo in-situ transformation from Ni species to Ni-OOH/OH phase during OER. Additionally, DFT calculations demonstrated that the F atoms could trigger charge redistribution, effectively activate adjacent Ni atoms and reduce the energy barrier of the rate-determining step (*OH→*O). The migration of fluorine species and the infiltration of electrolyte combine to yield an increased number of active sites, improved conductivity and hydrophilicity, enhanced catalytic activity and durability.