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The catalytic hydrogenation of CO2 to light olefins provides a promising route for converting greenhouse gases into value-added chemicals. In this work, a series of carbon nanosphere (CNS)-encapsulated Fe–Co core–shell catalysts with varying Fe/Co molar ratios were synthesized via resorcinol–formaldehyde polymerization followed by carbonization and evaluated for CO2 hydrogenation under atmospheric pressure. Among the catalysts investigated, CNS–Fe1Co2 exhibited comparatively improved catalytic performance, showing higher CO2 conversion and enhanced selectivity toward C2–C4 olefins relative to the monometallic CNS–Fe and CNS–Co catalysts. Structural characterization suggested the formation of a CNS-confined Fe– Co core–shell structure. XRD and XPS analyses indicated progressive transformation of Fe oxide species into carburized Fe-containing phases during reaction, while H2-TPR results suggested strong interaction between Fe and Co species. Raman spectroscopy and TGA results further indicated that the graphitic CNS framework remained largely preserved after reaction. The combined results suggest that Fe–Co interaction together with CNS confinement influences catalyst reducibility, carburization behavior, and structural stability during CO2 hydrogenation. 

ABSTRACT: Ethyl cellulose (EC) is a biocompatible, renewable, and recyclable material with diverse sources, making it an attractive candidate for industrial applications. Electrospinning has gained significant attention for the production of EC fibers. However, conventional electrospinning methods face challenges such as bead formation, low yield, and the absence of porous internal structures, limiting both the functional performance and scalability. This study presents an optimized approach for producing EC fibers by using a gravity-driven ultrahigh-speed electrospinning (GUHS-ES) system. This system leverages gravity to reshape the Taylor cone morphology during electrospinning, enhancing stability and dramatically increasing throughput. As flow rates increase, the Taylor cone contracts inward, while the tip structure expands and stabilizes, reaching maximum size at ultrahigh flow rates (100−150 mL/h). This unique Taylor cone structure enables a fiber production rate of 24.5 g/h, hundreds of times greater than conventional electrospinning techniques. Another advantage of the GUHS-ES system is its ability to achieve both high diameter uniformity and adjustable porosity. At ultrahigh flow rates, the pore sizes of the EC fibers reached 321 nm. The highly porous structure of EC fibers exhibited an absorption capacity of 56.6 to 110.7 times their weight, exceeding most previously reported oil-absorbing materials and demonstrating high efficacy for rapid waste oil absorption. This green, efficient technology represents a promising advancement for the large-scale production and application of natural polymer fibers with broad implications for sustainable industrial processes.