Large-Scale Nanofiber Manufacturing| Anchoring Co-Fe alloy nano-grains on carbonfibers by an in situ alloying strategy to boost thecatalytic performance for rapid oxidativedegradation of emerging contaminantsi

Professor Geng Longlong's Team at Dezhou University: Creation of CoFe Alloy-Anchored Carbon Fiber Catalysts via Alloying Strategy and Study on Oxidative Degradation Characteristics of Emerging Contaminants

The rapid development of modern industry has led to the emergence of new pollutants such as volatile organic compounds, endocrine disruptors, disinfection byproducts, and persistent pharmaceuticals. These refractory organic pollutants pose significant hazards to human health and the natural environment. Therefore, developing efficient, economical, and environmentally friendly technologies has become an important yet challenging task for tetracycline (TC) degradation.

Recently, Professor Geng Longlong's team at Dezhou University published their latest research titled "Anchoring Co-Fe alloy nano-grains on carbon fibers by an in situ alloying strategy to boost the catalytic performance for rapid oxidative degradation of emerging contaminants" in Journal of Materials Chemistry A. The first author is Yang Man, a joint graduate student from Dezhou University and North University of China, with Professor Geng Longlong, Professor Xu Jing, and Associate Professor Zhang Yongzheng as corresponding authors.

The researchers prepared CoFe alloy-modified carbon nanofibers (CoFe/CF) through wet impregnation and temperature-controlled pyrolysis for oxidative degradation of TC. Comprehensive experimental analysis and density functional theory (DFT) simulations revealed that the synergistic integration of Fe and Co within the nanoalloy optimized the catalyst's electronic structure and enhanced redox properties, significantly improving peroxymonosulfate (PMS) activation capability. Moreover, the degradation intermediates exhibited lower ecotoxicity and phytotoxicity, confirming the system's mineralization potential for TC-containing wastewater.

The CoFe/CF composite was prepared via wet impregnation and temperature-controlled pyrolysis (Figure 1a). XRD patterns showed characteristic peaks at 44.87° and 65.31° corresponding to the (110) and (200) crystal planes of CoFe alloy (Figure 1b). SEM images revealed CF-800 maintained 10-15 µm diameter one-dimensional fibers with smooth surfaces (Figure 1c-d), while metal incorporation introduced surface roughness (Figure 1e-g). CoFe/CF-400 showed 100-200 nm particles (Figure 1h), CoFe/CF-600 displayed additional 50 nm nanoparticles (Figure 1i), and CoFe/CF-800 featured uniformly anchored 25-40 nm nanoparticles (Figure 1j), attributed to carbothermal reduction forming CoFe alloy.

TEM analysis showed CoFe alloy particles averaging 32.2 nm (Figure 2b), with lattice fringes of 0.20 nm spacing corresponding to the (110) plane (Figure 2c-d). EDS mapping confirmed homogeneous Co/Fe distribution (Figure 2f).

XPS analysis indicated predominant Co0/Co2+ and Fe0/Fe2+ species, with surface oxidation contributing to divalent states. X-ray absorption spectroscopy verified Co-Fe/Co, Co-O, Fe-Co/Fe, and Fe-O coordinations, confirming alloy formation. Shorter Co-Fe bond lengths compared to Co-Co/Fe-Fe optimized charge structure for enhanced catalytic activity.

Catalytic tests demonstrated synergistic PMS activation between CF and CoFe alloy, achieving 97.92×10-3 min-1 rate constant for TC removal - 6.1× and 2.6× higher than CoFe/CF-400 and CoFe/CF-600 systems respectively. The system showed broad applicability for various pollutants, anti-interference capability, and practical water treatment potential. Recycling tests and magnetic hysteresis loops confirmed catalyst reusability.

The adsorption behavior of PMS on CoFe alloy was studied using density functional theory (DFT). As shown in the figure, the adsorption energies (Eads) of O2 on PMS adsorbed on the Co and Fe sites of the CoFe alloy are both higher than those of O1 and O3 on PMS adsorbed on the Co and Fe sites. This may be beneficial for the adsorption of PMS during the reaction process. In addition, Co - O2 and Fe - O2 have shorter bond lengths. These results confirm that PMS tends to act on the Co sites in the CoFe alloy, especially for the O2 species.

Electron paramagnetic resonance (EPR) and free - radical quenching experiments were used to study the reactive oxygen species (ROS) present in the CoFe/CF - 800/PMS system. As shown in Figure 6a - f, both free - radicals (•OH, SO4•-, O2•-) and non - free - radicals (1O2) are involved in the degradation of TC. Through free - radical quenching experiments and calculating the relative contributions of various reactive oxygen species, it is known that TC is mainly degraded by free - radical oxidation. In addition, a possible mechanism for the activation of PMS and the degradation of TC in the CoFe/CF - 800/PMS system was also proposed.