Synthesis of “sea urchin”-like carbon nanotubes/porous carbon superstructures derived from waste biomass for treatment of various contaminants

Abstract

Novel “sea urchin”-like Ni nanoparticles embedded in N-doped carbon nanotubes (CNTs) supported on porous carbon (Ni@N-C) 3D materials derived from waste biomass were prepared via pyrolysis and employed as an environmentally friendly, easy available and cost-effective catalyst for removal of toxic pollutants. The characterizations indicated that Ni0 catalyzed the growth of intertwined CNTs on carbon layers, affording abundant porous structures and larger specific surface area. With the synergistic effect of embedded Ni0 nanoparticles, nitrogen doping, hierarchical micro-mesopores, and interconnected CNTs, Ni@N-C displayed a superior catalytic capability for the oxidation of organic pollutants using peroxymonosulfate as an oxidant, and catalytic reduction of toxic CrVI to nontoxic CrIII by formic acid as a reducing agent. It was found that pyrolysis temperatures affected the compositions, morphologies, and catalytic properties of Ni@N-C. Inactive oxidized N species have transformed to the highly active graphitic N, pyridinic-N, and Ni-O-N clusters, thereby improving the catalytic activity. Moreover, Ni@N-C maintained good physicochemical structure and stable activity even after several cycles of reactions. The simple synthetic strategies, 3D structure, and remarkable performance of Ni@N-C composites make them serve as alternative environmentally friendly catalysts for removal of pollutants.