Three-dimensional cobalt@carbon foams decorated with nanospheres: Engineering hierarchical architectures and redox-active interfaces for advanced environmental catalysis

Abstract

The development of effective catalysts for Oxone activation is essential to improve advanced oxidation processes targeting recalcitrant pollutants. However, limited understanding of how structural and surface properties influence catalytic performance remains a major challenge. In this study, we prepared a Co@carbon foam (CCF) with a 3D porous architecture and systematically compared it to a non-supported cobalt-carbon material, Co@carbon ball (CB), to clarify their physicochemical differences and catalytic behavior. The CCF was synthesized by a glycerol-assisted hydrothermal process followed by pyrolysis, yielding a high surface area composite with uniformly dispersed cobalt species and abundant lattice oxygen. Compared to Co3O4 and CB, CCF exhibits significantly enhanced Oxone activation for the degradation of Acid Red 27 (AR), a carcinogenic azo dye, achieving a pseudo-first-order rate constant of 0.087 min-1. Surface analyses revealed that the foam structure improves cobalt-carbon synergy, increases defect density, and weakens Co-O bonds, facilitating ROS generation. DFT calculations and Fukui index mapping confirmed that the azo nitrogen atoms are key reactive sites, consistent with LC-MS detection of degradation products. The catalyst maintains high activity under diverse pH, salinity, and water conditions and demonstrates excellent reusability. These findings highlight how rational design and comparative evaluation of cobalt-carbon architectures can advance sustainable wastewater treatment.