Harnessing the Synergy of Fe and Co with Carbon Nanofibers for Enhanced CO

Amid growing concerns about climate change and energy sustainability, the need to create potent catalysts for the sequestration and conversion of CO2 to value-added chemicals is more critical than ever. This work describes the successful synthesis and profound potential of high-performance nanofiber catalysts, integrating earth-abundant iron (Fe) and cobalt (Co) as well as their alloy counterpart, FeCo, achieved through electrospinning and judicious thermal treatments. Systematic characterization using an array of advanced techniques, including SEM, TGA-DSC, ICP-MS, XRF, EDS, FTIR–ATR, XRD, and Raman spectroscopy, confirmed the integration and homogeneous distribution of Fe/Co elements in nanofibers and provided insights into their catalytic nuance. Impressively, the bimetallic FeCo nanofiber catalyst, thermally treated at 1050 °C, set a benchmark with an unparalleled CO2 conversion rate of 46.47% at atmospheric pressure and a consistent performance over a 55 h testing period at 500 °C. Additionally, this catalyst exhibited prowess in producing high-value hydrocarbons, comprising 8.01% of total products and a significant 31.37% of C2+ species. Our work offers a comprehensive and layered understanding of nanofiber catalysts, delving into their transformations, compositions, and structures under different calcination temperatures. The central themes of metal–carbon interactions, the potential advantages of bimetallic synergies, and the importance of structural defects all converge to define the catalytic performance of these nanofibers. These revelations not only deepen our understanding but also set the stage for future endeavors in designing advanced nanofiber catalysts with bespoke properties tailored for specific applications

Self-assembly of copper nanoparticles (cubes, rods and spherical nanostructures): significant role of morphology on hydrogen and oxygen evolution efficiencies

Nanocrystalline copper nanoparticles with varying morphology, nanocubes (~50 nm), nanorods (diameter of ~3 ~50 nm) and nanospheres (5 nm) have been synthesized using the microemulsion method and subsequent treatment at 400 °C in hydrogen atmosphere. The role of concentration in the self-assembly of nanoparticles in varying dimensionality has been brought out in this study. Copper nanoparticles are known to be efficient electro-catalysts for a variety of reactions. In addition, the ability of copper catalyst to generate hydrogen and oxygen in electrochemical reactions provided the impetus to understand size and shape dependence of such electro-catalytic reactions of copper in nanocrystalline form. Cube-shaped nanoparticles show significantly high hydrogen and oxygen evolution efficiencies compared to the nanorods and spherical nanoparticles. The nanospheres show higher hydrogen and oxygen evolution efficiencies than the nanorods

Binary Fe−Co Alloy Nanoparticles Showing Significant Enhancement in Electrocatalytic Activity Compared with Bulk Alloys

Microemulsion-based synthesis of Fe−Co alloy nanoparticles has been reported for the first time. Spherical, uniform, and highly monodisperse nanoparticles of Fe75Co25, Fe67Co33, Fe50Co50, and Fe33Co67 with an average size of 20, 25, 10, and 40 nm, respectively, were synthesized. These nanoparticles crystallize in a body-centered cubic cell. A higher cobalt content led to the formation of biphasic mixtures. Energy-dispersive X-ray spectroscopy studies confirmed the Fe/Co ratios. Nanoparticles of the Fe33Co67 alloy show higher hydrogen and oxygen evolution efficiencies (over 100 times) compared with other Fe−Co alloys of nanocrystalline or bulk form. The Fe−Co alloy nanoparticles also show ferromagnetism

Enhanced Electrocatalytic Activity of Copper-Cobalt Nanostructures

Novel core–shell nanostructures containing Cu and Co have been synthesized using the microemulsion method at 700 °C. The core consists of Cu–Co composite particles, whereas the shell is composed of Cu–Co alloy particles (shell thickness 12 nm). It is to be noted that in bulk Cu–Co binary system there is practically no miscibility. TEM studies show formation of spherical-shaped nanoparticles of core–shell structures. The composition of the core (Cu–Co composite) and shell (Cu–Co alloy) were confirmed by XPS studies. The formation of the Cu–Co alloy as the shell is mainly driven by surface energy considerations. We have also obtained Cu–Co nanocomposites (by controlling the concentration of reducing agent) with particle size in the range of 40–200 nm. These Cu–Co nanostructures show ferromagnetic behavior at 4 K. The saturation magnetization of the core–shell (Cu–Co composite @ Cu–Co alloy) nanostructure (125 emu/g) is found to be higher than that of pure Cu–Co nanocomposite or alloy, which may be useful for applications as a soft magnet. Electrochemical studies of these nanocrystalline Cu–Co particles show higher hydrogen evolution efficiencies (5 times) compared to bulk (micrometer-sized) Cu–Co alloy particles