Carbon nitride supported Co single-atom catalyst with low metal leaching for activation of peroxymonosulfate to degrade p-nitrophenol

Abstract

The development of efficient and practical catalysts has garnered significant attention in advanced oxidation systems. In this work, a carbon nitride supported single-atom cobalt catalyst (Co-NC) was synthesized using carbon black as the precursor for the carbon carrier through a co-pyrolysis method. This catalyst was then utilized to activate peroxymonosulfate (PMS) and degrade p-nitrophenol (PNP). Through experimental investigation, it was found that the optimal conditions for synthesizing the Co-NC catalyst, which exhibited the best catalytic performance, involved setting the cobalt acetate tetrahydrate to carbon black ratio at 0.4 mol/g, the cobalt acetate tetrahydrate to 1,10-phenanthroline ratio at 1:3, and the pyrolysis temperature at 650 °C. With a cobalt content of only 0.4 wt%, the catalyst exhibits a specific surface area of 372.6 m²/g and an optimal defect degree of 1.04. Under the catalytic action driven by singlet oxygen-identified as the primary active species via EPR-the degradation rate of PNP reaches 95 % within 30 min. The high catalytic activity of Co-NC catalyst derived from its unique CoN coordination and bond length. Notably, the concentration of Co ions leaching in the reaction solution remains below 0.05 mg/L. Additionally, experimental evidence confirms its applicability across diverse water qualities. This study presented a new single-atom catalyst with excellent PMS activation and provided valuable insights into the rational design of catalysts with low metal ion leaching.