Fe, Cu-coordinated ZIF-derived bimetal encapsulated N‑doped carbon nanotube for efficient remediation of various aqueous pollutants

Abstract

Exploring highly stable and efficient non-precious metal catalysts for decontamination of various non-biodegradable contaminants is a major challenge. Herein, Fe, Cu-coordinated ZIF-derived bimetal encapsulated N-doped carbon nanotubes (Fe-Cu@N-C) were developed and employed as novel bifunctional catalysts for organic oxidation and CrVI reduction. Pyrolysis of ZIF-8 containing Fe2+ and Cu2+ has successfully produced Cu nanoparticles and atom-dispersed Fe bimetals embedded in N-doped carbon nanotube catalysts. It was observed that the obtained optimal Fe-Cu@N-C possessed outstanding activity and stability for efficient degradation of organic contaminants via PMS activation, and toxic CrⅥ reduction with Formic acid (FA) as the reductant. Singlet oxygen (1O2·) was verified as the dominant active species for organic oxidation, while surface-adsorbed atomic hydrogen (H*) was responsible for effective reduction of CrVI to CrIII in the Fe-Cu@N-C/FA system. Compared with other ZIF derived systems such as Fe@N-C, Cu@N-C, and metal-free N-C, Fe-Cu@N-C exhibited prominent catalytic activities, which were attributed to bimetallic active sites (Fe-Nx and Cu-Nx), high N-doped level, large surface area and conductivity of porous carbon structure for fast mass and electron transport. This report provides a new approach to design highly efficient multifunctional catalysts for the purification of water to remove various types of pollutants.