Solar enhanced oxygen evolution reaction with transition metal telluride.

The photo-enhanced electrocatalytic method of oxygen evolution reaction (OER) shows promise for enhancing the effectiveness of clear energy generation through water splitting by using renewable and sustainable source of energy. However, despite benefits of photoelectrocatalytic (PEC) water splitting, its uses are constrained by its low efficiency as a result of charge carrier recombination, a large overpotential, and sluggish reaction kinetics. Here, we illustrate that Nickel telluride (NiTe) synthesized by hydrothermal methods can function as an extremely effective photo-coupled electrochemical oxygen evolution reaction (POER) catalyst. In this study, NiTe was synthesized by hydrothermal method at 145°C within just an hour of reaction time. In dark conditions, the NiTe deposited on carbon cloth substrate shows a small oxygen evolution reaction overpotential (261 mV) at a current density of 10 mA cm-2, a reduced Tafel slope (65.4 mV dec-1), and negligible activity decay after 12 h of chronoamperometry. By virtue of its enhanced photo response, excellent light harvesting ability, and increased interfacial kinetics of charge separation, the NiTe electrode under simulated solar illumination displays exceptional photoelectrochemical performance exhibiting overpotential of 165 mV at current density of 10 mA cm-2, which is about 96 mV less than on dark conditions. In addition, Density Functional Theory investigations have been carried out on the NiTe surface, the results of which demonstrated a greater adsorption energy for intermediate -OH on the catalyst site. Since the -OH adsorption on the catalyst site correlates to catalyst activation, it indicates the facile electrocatalytic activity of NiTe owing to favorable catalyst activation. DFT calculations also revealed the facile charge density redistribution following intermediate -OH adsorption on the NiTe surface. This work demonstrates that arrays of NiTe elongated nanostructure are a promising option for both electrochemical and photoelectrocatalytic water oxidation and offers broad suggestions for developing effective PEC devices.

Excellent Bifunctional Oxygen Evolution and Reduction Electrocatalysts (5A1/5)Co2O4 and Their Tunability.

Hastening the progress of rechargeable metal-air batteries and hydrogen fuel cells necessitates the advancement of economically feasible, earth-abundant, inexpensive, and efficient electrocatalysts facilitating both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Herein, a recently reported family of nano (5A1/5)Co2O4 (A = combinations of transition metals, Mg, Mn, Fe, Ni, Cu, and Zn) compositionally complex oxides (CCOs) [Wang et al., Chemistry of Materials, 2023,35 (17), 7283-7291.] are studied as bifunctional OER and ORR electrocatalysts. Among the different low-temperature soft-templating samples, those subjected to 600 °C postannealing heat treatment exhibit superior performance in alkaline media. One specific composition (Mn0.2Fe0.2Ni0.2Cu0.2Zn0.2)Co2O4 exhibited an exceptional overpotential (260 mV at 10 mA cm-2) for the OER, a favorable Tafel slope of 68 mV dec-1, excellent onset potential (0.9 V) for the ORR, and lower than 6% H2O2 yields over a potential range of 0.2 to 0.8 V vs the reversible hydrogen electrode. Furthermore, this catalyst displayed stability over a 22 h chronoamperometry measurement, as confirmed by X-ray photoelectron spectroscopy analysis. Considering the outstanding performance, the low cost and scalability of the synthesis method, and the demonstrated tunability through chemical substitutions and processing variables, CCO ACo2O4 spinel oxides are highly promising candidates for future sustainable electrocatalytic applications.

Tailored (La0.2Pr0.2Nd0.2Tb0.2Dy0.2)2Ce2O7 as a Highly Active and Stable Nanocatalyst for the Oxygen Evolution Reaction.

Designing highly active and robust catalysts for the oxygen evolution reaction is key to improving the overall efficiency of the water splitting reaction. It has been previously demonstrated that evaporation induced self-assembly (EISA) can be used to synthesize highly porous and high surface area cerate-based fluorite nanocatalysts, and that substitution of Ce with 50% rare earth (RE) cations significantly improves electrocatalyst activity. Herein, the defect structure of the best performing nanocatalyst in the series are further explored, Nd2Ce2O7, with a combination of neutron diffraction and neutron pair distribution function analysis. It is found that Nd3 + cation substitution for Ce in the CeO2 fluorite lattice introduces higher levels of oxygen Frenkel defects and induces a partially reduced RE1.5Ce1.5O5 + x phase with oxygen vacancy ordering. Significantly, it is demonstrated that the concentration of oxygen Frenkel defects and improved electrocatalytic activity can be further enhanced by increasing the compositional complexity (number of RE cations involved) in the substitution. The resulting novel compositionally-complex fluorite- (La0.2Pr0.2Nd0.2Tb0.2Dy0.2)2Ce2O7 is shown to display a low OER overpotential of 210 mV at a current density of 10 mAcm-2 in 1M KOH, and excellent cycling stability. It is suggested that increasing the compositional complexity of fluorite nanocatalysts expands the ability to tailor catalyst design.

Mesoporous RE0.5Ce0.5O2-x Fluorite Electrocatalysts for the Oxygen Evolution Reaction.

Developing highly active and stable electrocatalysts for the oxygen evolution reaction (OER) is key to improving the efficiency and practical application of various sustainable energy technologies including water electrolysis, CO2 reduction, and metal air batteries. Here, we use evaporation-induced self-assembly (EISA) to synthesize highly porous fluorite nanocatalysts with a high surface area. In this study, we demonstrate that a 50% rare-earth cation substitution for Ce in the CeO2 fluorite lattice improves the OER activity and stability by introducing oxygen vacancies into the host lattice, which results in a decrease in the adsorption energy of the OH* intermediate in the OER. Among the binary fluorite compositions investigated, Nd2Ce2O7 is shown to display the lowest OER overpotential of 243 mV, achieved at a current density of 10 mA cm-2, and excellent cycling stability in an alkaline medium. Importantly, we demonstrate that rare-earth oxide OER electrocatalysts with high activity and stability can be achieved using the EISA synthesis route without the incorporation of transition and noble metals.

Copper Cobalt Selenide as a Bifunctional Electrocatalyst for the Selective Reduction of CO2 to Carbon-Rich Products and Alcohol Oxidation.

Copper cobalt selenide, CuCo2Se4, has been identified as an efficient catalyst for electrocatalytic CO2 reduction, exhibiting high selectivity for carbon-rich and value-added products. Achieving product selectivity is one of the primary challenges for CO2 reduction reactions, and the catalyst surface plays a pivotal role in determining the reaction pathway and, more importantly, the intermediate adsorption kinetics leading to C1- or C2+-based products. In this research, the catalyst surface was designed to optimize the adsorption of the intermediate CO (carbonyl) group on the catalytic site such that its dwell time on the surface was long enough for further reduction to carbon-rich products but not strong enough for surface passivation and poisoning. CuCo2Se4 was synthesized through hydrothermal method, and the assembled electrode showed the electrocatalytic reduction of CO2 at various applied potentials ranging from -0.1 to -0.9 V vs RHE. More importantly, it was observed that the CuCo2Se4-modified electrode could produce exclusive C2 products such as acetic acid and ethanol with 100% faradaic efficiency at a lower applied potential (-0.1 to -0.3 V), while C1 products such as formic acid and methanol were obtained at higher applied potentials (-0.9 V). Such high selectivity and preference for acetic acid and ethanol formation highlight the novelty of this catalyst. The catalyst surface was also probed through density functional theory (DFT) calculations, and the high selectivity for C2 product formation could be attributed to the optimal CO adsorption energy on the catalytic site. It was further estimated that the Cu site showed a better catalytic activity than Co; however, the presence of neighboring Co atoms with the residual magnetic moment on the surface and subsurface layers influenced the charge density redistribution on the catalytic site after intermediate CO adsorption. In addition to CO2 reduction, this catalytic site was also active for alcohol oxidation producing formic or acetic acid from methanol or ethanol, respectively, in the anodic chamber. This report not only illustrates the highly efficient catalytic activity of CuCo2Se4 for CO2 reduction with high product selectivity but also offers a proper insight of the catalyst surface design and how to obtain such high selectivity, thereby providing knowledge that can be transformative for the field.

Carbon nanotube encapsulated metal selenide nanostructures for efficient electrocatalytic oxygen evolution reaction.

Nickel selenide nanowires were grown inside carbon nanotubes through in situ encapsulation via one-step chemical vapor deposition. These NiSe2@CNT nanohybrids showed excellent electrocatalytic activity for water splitting with a low overpotential of 260 mV at 10 mA cm-2, high current density, and extended stability owing to the synergistic effect between NiSe2 and CNTs.

A Molecular Tetrahedral Cobalt-Seleno-Based Complex as an Efficient Electrocatalyst for Water Splitting.

The cobalt-seleno-based coordination complex, [Co{(SePiPr2)2N}2], is reported with respect to its catalytic activity in oxygen evolution and hydrogen evolution reactions (OER and HER, respectively) in alkaline solutions. An overpotential of 320 and 630 mV was required to achieve 10 mA cm-2 for OER and HER, respectively. The overpotential for OER of this CoSe4-containing complex is one of the lowest that has been observed until now for molecular cobalt(II) systems, under the reported conditions. In addition, this cobalt-seleno-based complex exhibits a high mass activity (14.15 A g-1) and a much higher turn-over frequency (TOF) value (0.032 s-1) at an overpotential of 300 mV. These observations confirm analogous ones already reported in the literature pertaining to the potential of molecular cobalt-seleno systems as efficient OER electrocatalysts.

Electrochemical sensor based on CuSe for determination of dopamine.

A simple binary copper selenide, CuSe nanostructure, has been investigated as electrochemical sensor for dopamine detection. The hydrothermally synthesized and electrodeposited CuSe nanostructures showed high sensitivity for dopamine detection with low limit of detection (LOD). A sensitivity of 26 µA/µM.cm2 was obtained with this electrochemical sensor which is ideal to detect even small fluctuations in the transient dopamine concentration. Apart from high sensitivity and low LOD, the dopamine oxidation on the catalyst surface also occurred at a low applied potential (< 0.18 V vs Ag|AgCl), thereby significantly increasing selectivity of the process specifically with respect to ascorbic and uric acids, which are considered to be the most prominent interferents for dopamine detection. Electrochemical redox tunability of the catalytic Cu center along with low coordination geometry is believed to enhance the rate of dopamine attachment and oxidation on the catalyst surface thereby reducing the applied potential. The presence of Cu also increases conductivity of the catalyst composite which further improves the charge transfer thus increasing the sensitivity of the device. This is the first report of electrochemical dopamine sensing with a simple binary selenide comprising earth-abundant elements and can have large significance in designing efficient sensors that can be transformative for understanding neurodegenerative diseases further. Graphical abstract.

CuInSe2 nanotube arrays for efficient solar energy conversion.

Highly uniform and vertically aligned p-type CuInSe2 (CISe) nanotube arrays were fabricated through a unique protocol, incorporating confined electrodeposition on lithographically patterned nanoelectrodes. This protocol can be readily adapted to fabricate nanotube arrays of other photoabsorber and functional materials with precisely controllable design parameters. Ternary CISe nanotube arrays were electrodeposited congruently from a single electrolytic bath and the resulting nanotube arrays were studied through powder X-ray diffraction as well as elemental analysis which revealed compositional purity. Detailed photoelectrochemical (PEC) characterizations in a liquid junction cell were also carried out to investigate the photoconversion efficiency. It was observed that the tubular geometry had a strong influence on the photocurrent response and a 29.9% improvement of the photoconversion efficiency was observed with the nanotube array compared to a thin film geometry fabricated by the same process. More interestingly such enhancement in photoconversion efficiency was obtained when the electrode coverage with the nanotube arrays as photoactive material was only a fraction (~10%) of that for the thin film device. Apart from enhancement in photoconversion efficiency, this versatile technique provides ample opportunities to study novel photovoltaic materials and device design architectures where structural parameters play a key role such as resonant light trapping.

Ultrasensitive and Highly Selective Ni3Te2 as a Nonenzymatic Glucose Sensor at Extremely Low Working Potential.

Developing Nonenzymatic glucose biosensors has recently been at the center of attention owing to their potential application in implantable and continuous glucose monitoring systems. In this article, nickel telluride nanostructure with the generic formula of Ni3Te2 has been reported as a highly efficient electrocatalyst for glucose oxidation, functional at a low operating potential. Ni3Te2 nanostructures were prepared by two synthesis methods, direct electrodeposition on the electrode and hydrothermal method. The electrodeposited Ni3Te2 exhibited a wide linear range of response corresponding to glucose oxidation exhibiting a high sensitivity of 41.615 mA cm-2 mM-1 and a low limit of detection (LOD) of 0.43 µM. The hydrothermally synthesized Ni3Te2, on the other hand, also exhibits an ultrahigh sensitivity of 35.213 mA cm-2 mM-1 and an LOD of 0.38 µM. The observation of high efficiency for glucose oxidation for both Ni3Te2 electrodes irrespective of the synthesis method further confirms the enhanced intrinsic property of the material toward glucose oxidation. In addition to high sensitivity and low LOD, Ni3Te2 electrocatalyst also has good selectivity and long-term stability in a 0.1 M KOH solution. Since it is operative at a low applied potential of 0.35 V vs Ag|AgCl, interference from other electrochemically active species is reduced, thus increasing the accuracy of this sensor.

Facile one-pot synthesis of NiCo2Se4-rGO on Ni foam for high performance hybrid supercapacitors.

A facile, innovative synthesis for the fabrication of NiCo2Se4-rGO on a Ni foam nanocomposite via a simple hydrothermal reaction is proposed. The as-prepared NiCo2Se4-rGO@Ni foam electrode was tested through pxrd, TEM, SEM, and EDS to characterize the morphology and the purity of the material. The bimetallic electrode exhibited outstanding electrochemical performance with a high specific capacitance of 2038.55 F g-1 at 1 A g-1. NiCo2Se4-rGO@Ni foam exhibits an extensive cycling stability after 1000 cycles by retaining 90% of its initial capacity. A superior energy density of 67.01 W h kg-1 along with a high power density of 903.61 W kg-1 further proved the high performance of this electrode towards hybrid supercapacitors. The excellent electrochemical performance of NiCo2Se4-rGO@Ni foam can be explained through the high electrocatalytic activity of NiCo2Se4 in combination with reduced graphene oxide which increases conductivity and surface area of the electrode. This study proved that NiCo2Se4-rGO@Ni foam can be utilized as a high energy density-high power density electrode in energy storage applications.

A non-enzymatic glucose sensor based on a CoNi2Se4/rGO nanocomposite with ultrahigh sensitivity at low working potential.

Uniform and porous CoNi2Se4 was successfully synthesized by electrodeposition onto a composite electrode comprising reduced graphene oxide (rGO) anchored on a Ni foam substrate (prepared hydrothermally). This CoNi2Se4-rGO@NF composite electrode has been employed as an electrocatalyst for the direct oxidation of glucose, thereby acting as a high-performance non-enzymatic glucose sensor. Direct electrochemical measurement with the as-prepared electrode in 0.1 M NaOH revealed that the CoNi2Se4-rGO nanocomposite has excellent electrocatalytic activity towards glucose oxidation in an alkaline medium with a sensitivity of 18.89 mA mM-1 cm-2 and a wide linear response from 1 µM to 4.0 mM at a low applied potential of +0.35 V vs. Ag|AgCl. This study also highlights the effect of decreasing the anion electronegativity on enhancing the electrocatalytic efficiency by lowering the potential needed for glucose oxidation. The catalyst composite also exhibits high selectivity towards glucose oxidation in the presence of several interferents normally found in physiological blood samples. A low glucose detection limit of 0.65 µM and long-term stability along with a short response time of approximately 4 seconds highlights the promising performance of the CoNi2Se4-rGO@NF electrode for non-enzymatic glucose sensing with high precision and reliability.

Polymer coated gold-ferric oxide superparamagnetic nanoparticles for theranostic applications.

BACKGROUND: Engineered inorganic nanoparticles (NPs) are essential components in the development of nanotechnologies. For applications in nanomedicine, particles need to be functionalized to ensure a good dispersibility in biological fluids. In many cases however, functionalization is not sufficient: the particles become either coated by a corona of serum proteins or precipitate out of the solvent. We show that by changing the coating of magnetic iron oxide NPs using poly-L-lysine (PLL) polymer the colloidal stability of the dispersion is improved in aqueous solutions including water, phosphate buffered saline (PBS), PBS with 10% fetal bovine serum (FBS) and cell culture medium, and the internalization of the NPs toward living mammalian cells is profoundly affected. METHODS: A multifunctional magnetic NP is designed to perform a near-infrared (NIR)-responsive remote control photothermal ablation for the treatment of breast cancer. In contrast to the previously reported studies of gold (Au) magnetic (Fe3O4) core-shell NPs, a Janus-like nanostructure is synthesized with Fe3O4 NPs decorated with Au resulting in an approximate size of 60 nm mean diameter. The surface of trisoctahedral Au-Fe3O4 NPs was coated with a positively charged polymer, PLL to deliver the NPs inside cells. The PLL-Au-Fe3O4 NPs were characterized by transmission electron microscopy (TEM), XRD, FT-IR and dynamic light scattering (DLS). The unique properties of both Au surface plasmon resonance and superparamagnetic moment result in a multimodal platform for use as a nanothermal ablator and also as a magnetic resonance imaging (MRI) contrast agent, respectively. Taking advantage of the photothermal therapy, PLL-Au-Fe3O4 NPs were incubated with BT-474 and MDA-MB-231 breast cancer cells, investigated for the cytotoxicity and intracellular uptake, and remotely triggered by a NIR laser of ~ 808 nm (1 W/cm2 for 10 min). RESULTS: The PLL coating increased the colloidal stability and robustness of Au-Fe3O4 NPs (PLL-Au-Fe3O4) in biological media including cell culture medium, PBS and PBS with 10% fetal bovine serum. It is revealed that no significant (< 10%) cytotoxicity was induced by PLL-Au-Fe3O4 NPs itself in BT-474 and MDA-MB-231 cells at concentrations up to 100 µg/ml. Brightfield microscopy, fluorescence microscopy and TEM showed significant uptake of PLL-Au-Fe3O4 NPs by BT-474 and MDA-MB-231 cells. The cells exhibited 40 and 60% inhibition in BT-474 and MDA-MB-231 cell growth, respectively following the internalized NPs were triggered by a photothermal laser using 100 µg/ml PLL-Au-Fe3O4 NPs. The control cells treated with NPs but without laser showed < 10% cell death compared to no laser treatment control CONCLUSION: Combined together, the results demonstrate a new polymer gold superparamagnetic nanostructure that integrates both diagnostics function and photothermal ablation of tumors into a single multimodal nanoplatform exhibiting a significant cancer cell death.

Textured NiSe2 Film: Bifunctional Electrocatalyst for Full Water Splitting at Remarkably Low Overpotential with High Energy Efficiency.

Herein we have shown that electrodeposited NiSe2 can be used as a bifunctional electrocatalyst under alkaline conditions to split water at very low potential by catalyzing both oxygen evolution and hydrogen evolution reactions at anode and cathode, respectively, achieving a very high electrolysis energy efficiency exceeding 80% at considerably high current densities (100 mA cm-2). The OER catalytic activity as well as electrolysis energy efficiency surpasses any previously reported OER electrocatalyst in alkaline medium and energy efficiency of an electrolyzer using state-of-the-art Pt and RuO2 as the HER and OER catalyst, respectively. Through detailed electrochemical and structural characterization, we have shown that the enhanced catalytic activity is attributed to directional growth of the electrodeposited film that exposes a Ni-rich lattice plane as the terminating plane, as well as increased covalency of the selenide lattice which decreases the Ni(II) to Ni(III) oxidation potential. Thereby, the high efficiency along with extended stability makes NiSe2 as the most efficient water electrolyzer known to-date.

CoNi2Se4 as an efficient bifunctional electrocatalyst for overall water splitting.

CoNi2Se4 with a vacancy-ordered spinel structure shows excellent bifunctional electrocatalytic activity for water splitting in alkaline medium producing 10 mA cm-2 at a cell voltage of 1.61 V. For OER, an overpotential of 160 mV was needed for 10 mA cm-2 which is one of the lowest overpotentials reported to date.

A Molecular Ni-complex Containing Tetrahedral Nickel Selenide Core as Highly Efficient Electrocatalyst for Water Oxidation.

We report the highly efficient catalytic activity of a transition metal selenide-based coordination complex, [Ni{(SePi Pr2 )2 N}2 ], (1) for oxygen evolution and hydrogen evolution reactions (OER and HER, respectively) in alkaline solution. Very low overpotentials of 200 mV and 310 mV were required to achieve 10 mA cm-2 for OER and HER, respectively. The overpotential for OER is one of the lowest that has been reported up to now, making this one of the best OER electrocatalysts. In addition, this molecular complex exhibits an exceptionally high mass activity (111.02 A g-1 ) and a much higher TOF value (0.26 s-1 ) at a overpotential of 300 mV. This bifunctional electrocatalyst enables water electrolysis in alkaline solutions at a cell voltage of 1.54 V.

Cobalt Selenide Nanostructures: An Efficient Bifunctional Catalyst with High Current Density at Low Coverage.

Electrodeposited Co7Se8 nanostructures exhibiting flake-like morphology show bifunctional catalytic activity for oxygen evolution and hydrogen evolution reaction (OER and HER, respectively) in alkaline medium with long-term durability (>12 h) and high Faradaic efficiency (99.62%). In addition to low Tafel slope (32.6 mV per decade), the Co7Se8 OER electrocatalyst also exhibited very low overpotential to achieve 10 mA cm(-2) (0.26 V) which is lower than other transition metal chalcogenide based OER electrocatalysts reported in the literature and significantly lower than the state-of-the-art precious metal oxides. A low Tafel slope (59.1 mV per decade) was also obtained for the HER catalytic activity in alkaline electrolyte. The OER catalytic activity could be further improved by creating arrays of 3-dimensional rod-like and tubular structures of Co7Se8 through confined electrodeposition on lithographically patterned nanoelectrodes. Such arrays of patterned nanostructures produced exceptionally high mass activity and gravimetric current density (∼68 000 A g(-1)) compared to the planar thin films (∼220 A g(-1)). Such high mass activity of the catalysts underlines reduction in usage of the active material without compromising efficiency and their practical applicability. The catalyst layer could be electrodeposited on different substrates, and an effect of the substrate surface on the catalytic activity was also investigated. The Co7Se8 bifunctional catalyst enabled water electrolysis in alkaline solution at a cell voltage of 1.6 V. The electrodeposition works with exceptional reproducibility on any conducting substrate and shows unprecedented catalytic performance especially with the patterned growth of catalyst rods and tubes.

Enhancement of superconducting Tc (33 K) by entrapment of FeSe in carbon coated Au-Pd17Se15 nanoparticles.

FeSe has been an interesting member of the Fe-based superconductor family ever since the discovery of superconductivity in this simple binary chalcogenide. Simplicity of composition and ease of synthesis has made FeSe, in particular, very lucrative as a test system to understand the unconventional nature of superconductivity, especially in low-dimensional models. In this article we report the synthesis of composite nanoparticles containing FeSe nanoislands entrapped within an ent-FeSe-Pd16Se15-Au nanoparticle and sharing an interface with Pd17Se15. This assembly exhibits a significant enhancement in the superconducting Tc (onset at 33 K) accompanied by a noticeable lattice compression of FeSe along the <001> and <101> directions. The Tc in FeSe is very sensitive to application of pressure and it has been shown that with increasing external pressure Tc can be increased almost 4-fold. In these composite nanoparticles reported here, immobilization of FeSe on the Pd17Se15 surface contributes to increasing the effect of interfacial pressure, thereby enhancing the Tc. The effect of interfacial pressure is also manifested in the contraction of the FeSe lattice (up to 3.8% in <001> direction) as observed through extensive high-resolution TEM imaging. The confined FeSe in these nanoparticles occupied a region of approximately 15-25 nm, where lattice compression was uniform over the entire FeSe region, thereby maximizing its effect in enhancing the Tc. The nanoparticles have been synthesized by a simple catalyst-aided vapor transport reaction at 800 °C where iron acetylacetonate and Se were used as precursors. Morphology and composition of these nanoparticles have been studied in details through extensive electron microscopy.

Synthesis of superconducting nanocables of FeSe encapsulated in carbonaceous shell.

The recent discovery of superconductivity in iron selenide has attracted considerable attention due to the simplicity of composition, unconventional nature of superconductivity, and ease of synthesis. We have synthesized superconducting FeSe nanowires with a simple catalyst-aided vapor transport reaction at 800 °C in an inert atmosphere. The precursors were chosen to be elemental Se and iron acetylacetonate [Fe(III)(C5H8O2)3]. These vaporized very easily, thereby facilitating transport, and also contributed to the formation of a carbonaceous shell encapsulating the FeSe nanowires. The superconductivity of these nanocables was confirmed through magnetic measurements and a T(c) of ≈8 K was obtained for an ensemble of nanocables. The length of FeSe filling inside the carbon nanofibers could be varied by controlling the reaction conditions while the diameter of nanowires was dependent on the thickness of Au-Pd coating used as a catalyst. Extensive analysis through high-resolution microscopy revealed that there was considerable lattice contraction of FeSe in the nanocable up to about 3.6% along the c-direction leading to a reduced spacing between the (001) lattice planes. Interestingly, this compression was more pronounced near the catalyst-FeSe interface and was reduced further along the length of the nanocable. The presence of carbon nanofibers as a shell around the FeSe protected the FeSe nanowires from both atmospheric O2 and moisture attack, as was evident from the very long ambient condition shelf life of these nanocables, and also makes them more stable under e-beam irradiation.