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Anodic oxygen evolution reaction (OER) is essential to participate in diverse renewable energy conversion and storage processes, while most OER electrocatalysts present satisfactory catalytic performance in only alkaline or acidic medium, limiting their practical applications in many aspects. Herein, we have designed and prepared Ir-CeO2-C nanofibers (NFs) via an electrospinning and a relatively low-temperature calcination strategy for OER application in both alkaline and acidic conditions. Density functional theory (DFT) simulations demonstrate the high catalytic active sites of Ir atoms for OER, and that the formation of Ir—O bonds at the interface between Ir and CeO2 can modulate the electron density of the relevant Ir atoms to promote the OER activity. In addition, the unique nanofibrous heterostructure increases the exposed active sites and promotes the electrical conductivity. Therefore, the prepared Ir-CeO2-C nanofibrous catalyst delivers an excellent OER property in both alkaline and acidic solutions. Impressively, the overpotentials to reach 10 mA·cm−2 are only 279 and 283 mV in the alkaline and acidic electrolyte, respectively, with favorable long-term stabilities. In addition, the two-electrode overall water splitting set-ups equipped with Ir-CeO2-C NFs as anode and commercial Pt/C as cathode provide a cell voltage of 1.54 and 1.53 V to drive 10 mA·cm−2 in the alkaline and acidic electrolyte, respectively, which are much lower than Pt/C||IrO2 and lots of transition metal oxides-based electrolyzers. This research presents an efficient means to design OER catalysts with superior properties in both alkaline and acidic solutions. [ABSTRACT FROM AUTHOR]

Abstract Metal-organic framework nanosheets draw continuous attention in energy storage areas. In this work, for the first time, a facile strategy is developed to grow metal-organic framework nanosheets on electrospun nanofibers as supercapacitor electrode materials, exhibiting a high capacitance of 702.8 F g−1 at a current density of 0.5 A g−1 and excellent cycling stabilities over 10000 cycles. Through a specific carbonization process, the metal-organic framework based hybrids are preserved to produce a porous metal doped carbon material with the improved rate performance and a great prospect for cathode materials. Furthermore, an asymmetric solid-state supercapacitor device is assembled using the metal-organic framework based hybrids and metal doped carbon materials as anode and cathode materials, respectively. The maximum energy density of 51.4 Wh kg−1 with a power density of 1500.1 W kg−1 is achieved, which is superior to many previous reports, revealing a promising prospect for the novel high-performance asymmetric supercapacitor. Graphical abstract Image 1 Highlights • 2D Ni-MOF nanosheets grown on electrospun nanofibers are prepared. • The hybrid exhibits a high capacitance of 702.8 F g−1 and superior cycling life. • Ni-doped carbon materials derived from Ni-MOF based hybrids are synthesized. • An asymmetric solid-state supercapacitor based on the two materials is assembled. • The supercapacitor delivers a high energy density of 51.4 Wh kg−1. [ABSTRACT FROM AUTHOR]

Improving the conductivity and active surface area of electrospun carbon nanofibers is beneficial to develop binder-free supercapacitor electrodes for practical application prospects in energy storage field. Herein, we propose a facile and low-cost synthesis of hybrid electrospun carbon nanofibers composites (Ni-G-CNFs) coated with polyaniline throns (Ni-G-CNFs@PANI) via a combination of electrospinning and followed by carbonization and in situ polymerization processes. The prepared Ni-G-CNFs@PANI as a novel binder-free electrode exhibits a high specific capacitance of 318.0 F g −1 at a current density of 0.5 A g −1 and an acceptable capacitance retention of 62.1% when the current density increased from 0.5 A g −1 to 10 A g −1 in three-electrode system. Furthermore, a symmetric all solid-state supercapacitor was assembled by two binder-free electrodes, and the maximum energy density of 14.4 Wh kg −1 and maximum power density of 3750.2 W kg −1 were achieved in a potential window of 1.5 V. Capacitance retention remained 85.8% after 1000 cycles of charge-discharge process even at a high current density of 10 A g −1 . This strategy for growing PANI on electrospun hybrid CNFs paves a new avenue for construction of high-performance binder-free energy storage devices. [ABSTRACT FROM AUTHOR]

Improving the conductivity and specific surface area of electrospun carbon nanofibers (CNFs) is beneficial to a rapid realization of their applications in energy storage field. Here, a series of one-dimensional C/MO x (M = Mn, Cu, Co) nanostructures are first prepared by a simple two-step process consisting of electrospinning and thermal treatment. The presence of low-valence MO x enhances the porosity and conductivity of nanocomposites to some extent through expanding graphitic domains or mixing metallic Cu into the CNF substrates. Next, the C/MO x frameworks are coated with MnO 2 nanosheets/nanowhiskers (C/MO x @MnO 2 ), during which process the low-valence MO x can partly reduce KMnO 4 so as to mitigate the consumption of CNFs. When used as active materials for supercapacitor electrodes, the obtained C/MO x @MnO 2 exhibit excellent electrochemical performances in comparison with the common CNFs@MnO 2 (CM) core-shell electrode due to the combination of desired functions of the individual components and the introduction of extra synergistic effect. It is believed that these results will provide an alternative way to further increase the capacitive properties of CNFs- or metal oxide-based nanomaterials and potentially stimulate the investigation on other kinds of C/MO x composite nanostructures for various applications. [ABSTRACT FROM AUTHOR]

A simple and low cost detection of l-cysteine is essential in the fields of biosensors and medical diagnosis. In this study, we have developed a simple electrospinning, followed by calcination process to prepare FeCo nanoparticles embedded in carbon nanofibers (FeCo-CNFs) as an efficient peroxidase-like mimic for the detection of l-cysteine. FeCo nanoparticles are uniformly dispersed within CNFs, and their diameters are highly influenced by the calcination temperature. The calcination temperature also influences the peroxidase-like catalytic activity, and the maximum activity is achieved at a calcination temperature of 550 °C. Owing to the high catalytic activity of the as-prepared FeCo-CNFs, a colorimetric technique for the rapid and accurate determination of l-cysteine has been developed. The detection limit is about 0.15 μM with a wide linear range from 1 to 20 μM. In addition, a high selectivity for the detection of l-cysteine over other amino acids, glucose and common ions is achieved. This study provides a simple, rapid and sensitive sensing platform for the detection of l-cysteine, which is a promising candidate for potential applications in biosensing, medicine, environmental monitoring. [ABSTRACT FROM AUTHOR]

[Display omitted] • Partially oxidized Ru/Rh nanoparticles embedded in carbon nanofibers are prepared. • The catalyst presents a superior alkaline HER and HzOR performance under a large current density. • The catalyst provides more active sites and superior electron transfer to promote the electrocatalytic property. • The overall hydrazine splitting cell shows a low cell voltage and excellent durability. Hydrazine oxidation reaction (HzOR), an alternative to oxygen evolution reaction, effectively mitigates hydrazine pollution while achieving energy-efficient hydrogen production. Herein, partially oxidized Ru/Rh nanoparticles embedded in carbon nanofibers (CNFs) are fabricated as a bifunctional electrocatalyst for hydrogen evolution reaction (HER) and HzOR. The presence of multiple components including metallic Ru and Rh and their oxides provides numerous electrochemically active sites and superior charge transfer properties, thus improving the electrocatalytic performance. Additionally, the confinement of the active components within CNFs further enhances structural stability. Consequently, the optimized electrocatalyst exhibits ultralow overpotentials of 16 mV at 10 mA cm−2 and 176 mV to reach an industry-level current density of 1 A cm−2 for HER, considerably outperforming the benchmark Pt/C catalyst. Furthermore, it shows an outstanding anodic HzOR activity, achieving a small potential of –0.019 V to generate 10 mA cm−2. A two-electrode overall hydrazine splitting (OHzS) cell prepared using the electrocatalyst operates at a compelling voltage that is 1.953 V lower than that of the overall water splitting (OWS) cell at 200 mA cm−2. Furthermore, the OHzS cell achieves a hydrogen production rate of 1.17 mmol h−1, which is 15-fold that of OWS. Additionally, Rh 1 Ru 1 O x -CNFs-350 is used to construct a Zn-hydrazine battery with excellent performance. This study presents an effective system for achieving high-yielding green H 2 production with low energy consumption while simultaneously addressing hydrazine pollution. [ABSTRACT FROM AUTHOR]

Developing high‐performance, low‐cost, and robust bifunctional electrocatalysts for overall water splitting is extremely indispensable and challenging. It is a promising strategy to couple highly active precious metals with transition metals as efficient electrocatalysts, which can not only effectively reduce the cost of the preparation procedure, but also greatly improve the performance of catalysts through a synergistic effect. Herein, Ru and Ni nanoparticles embedded within nitrogen‐doped carbon nanofibers (RuNi‐NCNFs) are synthesized via a simple electrospinning technology with a subsequent carbonization process. The as‐formed RuNi‐NCNFs represent excellent Pt‐like electrocatalytic activity for the hydrogen evolution reaction (HER) in both alkaline and acidic conditions. Furthermore, the RuNi‐NCNFs also exhibit an outstanding oxygen evolution reaction (OER) activity with an overpotential of 290 mV to achieve a current density of 10 mA cm−2 in alkaline electrolyte. Strikingly, owing to both the HER and OER performance, an electrolyzer with RuNi‐NCNFs as both the anode and cathode catalysts requires only a cell voltage of 1.564 V to drive a current density of 10 mA cm−2 in an alkaline medium, which is lower than the benchmark of Pt/C||RuO2 electrodes. This study opens a novel avenue toward the exploration of high efficient but low‐cost electrocatalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

The cover representing article number 1803185, by Xiaofeng Lu and co‐workers illustrates the fabrication of carbon nanofibers integrated with Ni and Mo2C nanoparticles as water splitting electrocatalysts for both HER and OER. An alkaline electrolyzer with the electrocatalysts for both anode and cathode is constructed and shows an excellent electrocatalytic activity and stability, which are expected to lead to promising applications in efficient energy storage and conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bimetal phosphide embedded in carbon nanofibers (P-FeNi/CNFs) are fabricated via a reliable strategy. • The P-FeNi/CNFs catalyst shows an excellent conductivity and robust structural stability. • The P-FeNi/CNFs catalyst presents a high OER activity and desirable durability in an alkaline medium. • The theoretical result shows the weakening of the O intermediate adsorption to promote the OER activity. The development of non-precious metal electrocatalysts for oxygen evolution reaction (OER) is crucial for generating large-scale hydrogen through water electrolysis. In this work, bimetal phosphides embedded in electrospun carbon nanofibers (P-FeNi/CNFs) were fabricated through a reliable electrospinning–carbonization–phosphidation strategy. The incorporation of P-FeNi nanoparticles within CNFs prevented them from forming aggregation and further improved their electron transfer property. The bimetal phosphides helped to weaken the adsorption of O intermediate, promoting the OER activity, which was confirmed by the theoretical results. The as-prepared optimized P-Fe 1 Ni 2 /CNFs catalyst exhibited very high OER electrocatalytic performance, which required very low overpotentials of just 239 and 303 mV to reach 10 and 1000 mA cm−2, respectively. It is superior to the commercial RuO 2 and many other related OER electrocatalysts reported so far. In addition, the constructed alkaline electrolyzer based on the P-Fe 1 Ni 2 /CNFs catalyst and Pt/C delivered a cell voltage of 1.52 V at 10 mA cm−2, surpassing the commercial RuO 2 ||Pt/C (1.61 V) electrolyzer. It also offered excellent alkaline OER performance in simulated seawater electrolyte. This demonstrated its potential for practical applications across a broad range of environmental conditions. Our work provides new ideas for the ration design of highly efficient non-precious metal-based OER catalysts for water electrolysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rh nanoparticles anchored on Co/ N -doped carbon nanofibers are prepared via an electrospinning-pyrolysis-reduction method. • The nanofibrous hybrid catalyst shows rich exposed active sites and excellent electrical conductivity. • The nanofibrous hybrid catalyst presents high HER activities in both alkaline and acidic media. • The nanofibrous hybrid catalyst presents an excellent long-term stability towards HER. Constructing high-activity electrocatalysts towards hydrogen evolution reaction (HER) is an essential way to achieve efficient, green and sustainable energy from water electrolysis. In this work, rhodium (Rh) nanoparticles anchored on cobalt (Co)/nitrogen (N)-doped carbon nanofibers (NCNFs) catalyst is prepared by the electrospinning-pyrolysis-reduction method. The synergy effect between Co-NCNFs and Rh nanoparticles contributes to the superior HER activity and favorable durability. The optimized 0.15Co-NCNFs-5Rh sample exhibits ultralow overpotentials of 13 and 18 mV to reach 10 mA cm−2 in an alkaline and acidic electrolyte, surpassing many Rh-based or Co-based electrocatalysts reported in the literature. Additionally, the Co-NCNFs-Rh sample shows a better HER activity than benchmark Pt/C catalyst in an alkaline medium at all current densities and in an acidic condition at higher current densities, offering its promising practical applications. Thus, this work provides an efficient methodology to construct high-performance HER electrocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrafine Ir nanoparticles on N -doped carbon nanofibers (NCNFs) are fabricated via an chelating adsorption-engaged synthesis strategy. • The nanofibrous heterostructure increases the exposed active sites and promotes the electrical conductivity. • The Ir-NCNFs catalyst presents large HER activity in both alkaline and acidic solutions. • The Ir-NCNFs catalyst also shows an admirable durability during HER process. Developing highly efficient and stable precious metal electrocatalysts toward hydrogen evolution reaction (HER) is crucial for energy application, while it is still challenging to achieve highly dispersed ultrafine metal nanoparticles on some promising supports to synergistically promote their electrocatalytic performance. Herein, we propose a feasible chelating adsorption-engaged strategy by introducing de-doped polyaniline with abundant amino groups to immobilize ultrafine iridium (Ir) nanoparticles on their derived N -doped carbon nanofibers (Ir-NCNFs). Experimental results demonstrate that the synthesized Ir-NCNFs can effectively promote the charge transfer and expose more electrochemical active sites, which eventually accelerate the reaction kinetics. Thus, the synthesized Ir-NCNFs catalyst exhibits admirable HER activities in both alkaline and acidic conditions with overpotentials of only 23 and 8 mV, which are even superior or close to the benchmark Pt/C catalyst. Furthermore, the synthesized Ir-NCNFs catalyst also exhibits a long-term durability. This study affords a reliable means to construct high-performance supported ultrafine metal nanocatalysts for electrocatalytic applications to alleviate the growing demand for energy conversion. [ABSTRACT FROM AUTHOR]

Abstract: Carbon/CdS coaxial nanofibers (NFs) have been prepared using polyacrylonitrile (PAN)/CdS composite NFs as precursors. The synthesis strategy involves immersing the as-spun PAN fibers into cadmium acetate aqueous solution, followed by reaction with H2S gas and carbonization. SEM and TEM showed the morphology of the obtained coaxial NFs. The structures were examined by XRD, FT-IR and Raman spectra. The NFs displayed photoluminescence and conductive properties which were characterized by room-temperature photoluminescent spectra and standard four-probe method. [Copyright &y& Elsevier]

The (Ni,Fe)S 2 /NiFe(3:1)-CNFs exhibit a highly efficient property for oxygen evolution reaction at a low potential in an alkaline medium. [Display omitted] • Fe-doped NiS 2 crystals on NiFe-carbon nanofibers are successfully prepared. • The electrocatalyst shows abundant exposed active sites and excellent electron/mass transport properties. • The electrocatalyst presents a low overpotential of 287 mV at 30 mA cm−2 for OER. • The overall water splitting device exhibits a cell voltage of 1.54 V to attain 10 mA cm−2. The construction of high-efficiency and low-cost electrocatalysts toward oxygen evolution reaction (OER) to improve the overall water decomposition performance is a fascinating route to deal with the clean energy application. Herein, Fe-doped NiS 2 crystals grown on the surface of carbon nanofibers (CNFs) encapsulated with NiFe alloy nanoparticles ((Ni,Fe)S 2 /NiFe-CNFs) are fabricated through an electrospinning-calcination-vulcanization process, which has been used as a splendid electrocatalyst for OER. Benefitting from the abundant electrochemical active sites from the incorporation of Fe element in NiS 2 and the synergistic effect between NiFe-CNFs and surface sulfides, the obtained (Ni,Fe)S 2 /NiFe-CNFs catalyst exhibits highly electrochemical activities and satisfactory durability toward OER in an alkaline medium with a low overpotential of only 287 mV at a high current density of 30 mA cm−2, and with a little decline in the current retention after 48 h, suggesting its superior OER performance even compared with some noble metal-based electrocatalysts. Additionally, a two-electrode system conducted by using the (Ni,Fe)S 2 /NiFe-CNFs and commercial Pt/C as electrodes, only needs a cell voltage of 1.54 V to afford 10 mA cm−2 for overall water splitting, which is even much better than the RuO 2 ||Pt/C electrolyzer. This study offers a promising approach to prepare high-efficiency OER catalysts toward overall water splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon nanofibers (CNFs) embedded with PdCo alloy nanoparticles are successfully prepared. • The electrocatalyst shows a large surface area and strong electron transfer between components. • The electrocatalyst presents a low working potential of only 258 mV at 50 mA cm−2 for HzOR. • The overall hydrazine splitting delivers a low cell voltage of 0.440 V to drive 10 mA cm−2. Electrolytic water splitting is a promising strategy to generate clean hydrogen energy but still restricted by the sluggish kinetics during the anodic oxygen evolution reaction (OER). A highly efficient route to significantly reduce the cell voltage of electrolytic water splitting is to replace OER with hydrazine oxidation reaction (HzOR) so as to assist hydrogen generation effectively. Here, we report the fabrication of carbon nanofibers (CNFs) embedded with palladium cobalt (PdCo) alloy nanoparticles, via an electrospinning followed by a carbonization treatment. The as-synthesized PdCo-CNFs catalyst displays a superior electrocatalytic activity toward HzOR with a working potential of 258 mV (vs. RHE) to drive a current density of 50 mA cm−2 in an alkaline solution with 0.2 M hydrazine. Furthermore, the favorable hydrogen evolution reaction (HER) activity of this catalyst enables it highly efficient electrolytic hydrogen production, and the two-electrode system using PdCo-CNFs as both the cathode and anode for overall hydrazine splitting is capable of delivering a cell voltage of 0.440 V to attain 10 mA cm−2, which is 1.496 V less than that for pure water splitting using the same electrodes and even 0.459 V less than the overall hydrazine splitting device using Pt/C//RuO 2 as electrocatalysts. This work provides a reliable way for the fabrication of promising bifunctional electrocatalysts to promote energy-saving hydrogen production for practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bimetallic Sn-alloy coupling with carbon nanofiber (CNF) has been prepared. • The CoSn-CNF catalyst presents a superior electrochemical nitrate reduction reaction (NO 3 RR) performance. • The d-band center of the catalyst is modulated by alloying to promote the NO 3 RR efficiency. • An aqueous Zn-NO 3 − battery using CoSn-CNF as the cathode shows a remarkable power density. The production of ammonia from electrochemical nitrate reduction reaction (NO 3 RR) has emerged as a highly promising approach to replace the conventional "Haber-Bosch" process, but the research progress of this field is still hindered by the absence of a structure–activity relationship for manipulating catalyst structure to promote its catalytic performance. In this study, we chose TMSn (M=Fe, Co, Ni) alloys as the models to evaluate the electronic structure and their NO 3 RR activity. Alloying various transition metals with Sn allows to regulate charge distribution, thereby modulating the d -band center of the catalysts and further regulating the catalytic activity of NO 3 RR. Density functional theory (DFT) simulation predicts that CoSn alloy, with the strongest NO 3 − adsorption and lowest thermodynamic energy barrier, is potentially considered as a highly efficient NO 3 RR catalyst. With this theoretical guidance, a series of TMSn alloy catalysts with carbon nanofiber (TMSn-CNF) as a support were synthesized via a two-step electrospinning/carbonization strategy. The CNF as a substrate ensures the excellent cycling performance. As a result, a significantly enhanced NO 3 RR activity with a NH 3 yield rate of 42.20 mg h−1 cm−2 at −0.6 V vs. RHE is achieved on CoSn-CNF compared with NiSn-CNF (13.91 mg h−1 cm−2), FeSn-CNF (13.81 mg h−1 cm−2) and Sn-CNF (6.10 mg h−1 cm−2), superior to most of the previously reported catalysts. We have further constructed an aqueous Zn-NO 3 − battery using CoSn-CNF as the cathode, achieving a remarkable power density of 5.88 mW cm−2. This battery not only generates large quantity of NH 3 , but also functions as an effective power source. [ABSTRACT FROM AUTHOR]

Platinum is the most commonly used dye-sensitized solar cell (DSSC) counter electrode (CE) due to its superior electrocatalytic activity and high transparency. However, the scarcity and high-cost of Pt restrict its practical application for the large-scale production of DSSCs. Herein, a facile approach for fabricating highly dispersed Co 9 S 8 nanoparticles with small diameters in the range of 5–10 nm on the surface of carbon nanofibers (CNFs) via an electrospinning followed by calcination and hydrothermal reaction was developed. The composite material could be used as an efficient and low-cost Pt-free CE for DSSCs. The DSSC assembled with the prepared Co 9 S 8 /CNFs composite as a CE exhibited excellent electrocatalytic activity and a power conversion efficiency (PCE) of 8.37%, which is comparable to that of the DSSC with conventional thermally deposited Pt as the CE (8.50%). Therefore, the Co 9 S 8 /CNFs composite can be used as an efficient and low-cost promising alternative CE in DSSCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Iridium incorporated cobalt-based hydroxide on nickel-doped carbon nanofibers are prepared. • The electrocatalyst shows unique nanofibrous morphology with a core-sheath structure and low crystallinity. • The electrocatalyst presents a low overpotential of 240 mV at 10 mA cm−2 for OER. • The Pt/C||Ni-CNFs/Ir-Co(OH) 2 electrolyzer exhibits a cell voltage of 1.50 V to attain 10 mA cm−2. The construction of high-performance oxygen evolution reaction (OER) electrocatalysts is crucial for energy applications. Here, we demonstrate a reliable route to incorporate iridium (Ir) into cobalt (Co)-based hydroxide derived from ZIF-67 on the surface of Ni-contained carbon nanofibers (denoted as Ni-CNFs/Ir-Co(OH) 2) as an electrocatalyst to boost its alkaline OER property. The optimized Ni-CNFs/Ir-Co(OH) 2 sample exhibits an extraordinary OER activity with an overpotential of only 240 mV to reach 10 mA cm−2, much lower than that of commercial IrO 2 electrocatalyst (331 mV). The theoretical results illustrate the highly active Co sites of Ir edge -Co(OH) 2 for OER. Furthermore, the distinct nanofibrous architecture of Ni-CNFs endows with a desirable electrical conductivity of the catalyst, thus the Ni-CNFs/Ir-Co(OH) 2 sample presents a desirable durability for OER testing. In addition, a total water electrolyzer is built by using the prepared Ni-CNFs/Ir-Co(OH) 2 and Pt/C as electrodes, which requires only 1.50 V at 10 mA cm−2, superior to the value of Pt/C||IrO 2 cell (1.62 V). This study puts forward an effective route to explore superior OER electrocatalysts by engineering the electronic structure of metal hydroxide for energy applications. [ABSTRACT FROM AUTHOR]

Among various methods for acquiring hydrogen fuel, electrocatalytic water splitting is considered to be as one of the most efficient and promising approaches. Pt is regarded as the best electrocatalyst for the hydrogen evolution reaction (HER) during water splitting process, however, the scarcity and costliness of Pt restrict the large-scale practical application. On the other hand, transition metal Ni is abundant in earth and exhibits favorable HER catalytic activity theoretically. In this work, we have demonstrated a facile electrospinning combined with calcination and chemical reduction processes to fabricate Pt nanoparticles loaded on nitrogen-doped carbon/Ni nanofibers (Ni-NCNFs-Pt) as efficient HER electrocatalysts. The as-prepared Ni-NCNFs-Pt not only reduced the usage of noble metal Pt but also revealed an excellent electrochemical activity at all values of pH, including the smaller overpotentials of 47, 22 and 84 mV (at j  = 10 mA cm −2 ) in 0.5 M H 2 SO 4 , 1 M KOH and 0.1 M phosphate buffer solution, respectively. In addition, Ni-NCNFs-Pt nanocatalyst displayed an extraordinary low Tafel slope and long durability over a wide range of pH. The remarkable HER performance could be ascribed to the increased electrochemical active surface area through the introduction of Ni nanoparticles, synergistic interactions between Ni and Pt nanoparticles and the introduction of the conductive nitrogen-doped carbon nanofibers (NCNFs) substrate which facilitated the fast electron transport. This investigation provides a potential route to construct efficient and low cost HER electrocatalysts with promising practical applications in renewable energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Low-loading and ultrasmall Ir nanoparticles on Ni/N-doped carbon nanofibers (NCNFs) are fabricated. • The nanofibrous NCNFs with both Ir and Ni provide rich exposed active sites and excellent electrical conductivity. • The Ni-NCNFs-Ir catalyst exhibits excellent HER activity in both acidic and alkaline media. • The Ni-NCNFs-Ir catalyst also presents a favorable durability during HER process. The construction of highly active and durable electrocatalysts for hydrogen production from water electrolysis in a wide pH range is crucial for the sustainable development of clean energy. In this work, low-loading and ultrasmall Ir nanoparticles decorated on the surface of Ni/nitrogen-doped carbon nanofibers (NCNFs) are rationally constructed through a simple chemical reduction deposition route. Benefiting from the rich electrochemical active sites and excellent electrical conductivity, the obtained Ni-NCNFs-Ir catalyst exhibits superior hydrogen evolution reaction (HER) activities in both acidic and alkaline solutions. Specifically, the optimized 0.1Ni-NCNFs-5Ir catalyst with Ir content of 6.0 wt% exhibits remarkable low overpotentials of 22 and 25 mV at 10 mA cm−2 in 0.5 M H 2 SO 4 and 1 M KOH, respectively, which are better than many other reported Ir- or Ni-based electrocatalysts. In addition, the prepared 0.1Ni-NCNFs-5Ir catalyst shows favorable durability. Our theoretical results reveal that the relevant C- and Ir-sites jointly contribute to the high HER catalytic property of the Ni-NCNFs-Ir system, and two complicated electron transfer processes (Ni → C → N and Ir → C → N) are beneficial to promote the electrocatalytic performance. This work provides a meaningful strategy to develop high-efficiency HER electrocatalysts in a wide pH range. [ABSTRACT FROM AUTHOR]

In this report, a flexible substrate was prepared for no background interference detection of small molecules with surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) via an electrospinning technique. The substrate is composed of polyamide (PA6)-carbon soot nanoparticles (CS NPs), in which CS NPs are evenly encapsulated in polyamide nanofibers. The encapsulation eliminates the interference of CS NPs during SALDI-MS detection. The prepared flexible substrate presents high sensitivity and good reproducibility and no interference in low mass range after hydrophobic treatment. With this substrate, small molecules can be successfully quantified with a limit of detection as low as 200 pmol. The detection results of the methadone in urine and the residual malachite green on fish skin demonstrate the promising applications of the substrate in analyzing real samples and directly sampling from irregular objects, which simplified sample pretreatment process. • PA6-C film as a flexible substrate was prepared for no background interference detection of small molecules with SALDI-MS. • PA6-C film presents high sensitivity and good reproducibility and no interference in low mass range. • The results of real samples demonstrate promising applications in analyzing and directly sampling from irregular samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three-dimensional core-shell Co-C@NiFe LDH nanofibers are successfully prepared. • The electrocatalyst shows a large surface area and strong electron transfer between components. • The electrocatalyst presents a low overpotential of only 249 mV at 10 mA cm−2 for OER. • The electrocatalyst exhibits a superior long-term stability over 190 h. In recent years, the design of high-performance and low-cost electrocatalysts for oxygen evolution reaction (OER) has captured great interest in the field of energy conversion and storage. Layered double hydroxide (LDH) with special configuration usually shows a highly electrochemical activity and become a desirable functional material for OER. In this work, carbon nanofibers embedded with Co nanoparticles have been prepared via an electrospinning and carbonization process, which can be served as a conductive support for the growth of NiFe LDH nanosheets through an electrodeposition route to produce a hierarchical 3D structure (denoted as 3D core-shell Co-C@NiFe LDH nanofibers). Owing to the high conductivity, large surface area and strong electron transfer between NiFe LDH nanosheets and Co-C nanofibers, the as-prepared 3D core-shell Co-C@NiFe LDH nanofibrous catalyst shows an excellent OER performance with an overpotential of only 249 mV at the current density of 10 mA cm−2 and a small Tafel slope of 57.9 mV dec−1, demonstrating an outstanding electrocatalytic activity for water oxidation. Furthermore, the 3D core-shell Co-C@NiFe LDH nanofibers also exhibit a superior long-term stability, with no obvious decrease in current density after nearly 190 h testing. Hence, the low-cost 3D core-shell Co-C@NiFe LDH nanofibrous electrocatalyst with an outstanding OER performance offers a novel chance for practical electrochemical water splitting application. [ABSTRACT FROM AUTHOR]

The development of highly efficient, earth-abundant and low-cost counter electrode materials is of significant importance and challenge for practical application in dye-sensitized solar cells. In this work, morphology-controlled NiCo 2 S 4 nanoparticles (NPs) and nanorods (NRs) decorating carbon nanofibers (CNFs) have been prepared via an electrospinning and hydrothermal or solvothermal strategy, which are further utilized as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Benefitting from the rich nickel and cobalt ions redox chemistry and more exposed catalytically active sites from NiCo 2 S 4 NRs grown vertically on the surface of CNFs as well as faster electron transporting capability providing by the highly conductive CNFs, the DSSC device based on NiCo 2 S 4 NRs/CNFs CE yields an excellent power conversion efficiency of 9.47%, which is higher than that of the devices with NiCo 2 S 4 NPs/CNFs (8.63%), Pt (8.18%) and CNFs (6.06%) as CEs under AM 1.5 G irradiation. Furthermore, the NiCo 2 S 4 NRs/CNFs CE shows an excellent electrochemical stability in an iodine-based electrolyte. This study highlights a controllable and versatile route to rational design efficient counter electrode catalysts for high-performance CEs application. [ABSTRACT FROM AUTHOR]

It is extremely necessary to develop high-performance noble-metal-free hydrogen evolution reaction (HER) electrocatalysts applied over the whole pH values to replace expensive Pt-based catalysts. Herein, a typical metal-semiconductor heterostructure with metallic Mo and Mo 2 C nanoparticles encapsulated in nitrogen-doped carbon nanofibers (N-CNFs) is fabricated via the pyrolysis of electrospun polyacrylonitrile (PAN)/cellulose acetate (CA)/bis(acetylacetonato)dioxomolybdenum (MoO 2 (acac) 2) nanofibers. The unique porous and channel-rich structure of Mo/Mo 2 C/N-CNFs can be manipulated by varying the mass ratio of polyacrylonitrile and cellulose acetate, leading to the exposure of abundant active centers and the acceleration of rapid mass transport. In addition, the synergetic effect among metal and semiconductor as well as the excellent conductivity of the N-CNFs result in excellent HER activity and stability over a wide pH range. To achieve the current density of 10 mA cm−2, the optimized Mo/Mo 2 C/N-CNFs exhibit overpotentials of 175, 162 and 294 mV in 0.5 M H 2 SO 4 , 1 M KOH and 0.1 M phosphate buffer solution (PBS), respectively. This work provides a feasible approach to synthesize high-performance and economical hydrogen evolution electrocatalysts at all pH values for renewable energy-related applications. Mo/Mo 2 C encapsulated in nitrogen-doped carbon nanofibers as efficient heterojunction electrocatalysts for hydrogen evolution reaction have been developed. Unlabelled Image • A strategy is developed to prepare Mo/Mo 2 C/N-CNFs heterojunction electrocatalysts. • The introduction of CA results in porous and channel-rich structure. • The Mo/Mo 2 C/N-CNFs show excellent HER activities over a wide pH range. • N-doped CNFs promote the continuous electron transport between Mo and Mo 2 C. [ABSTRACT FROM AUTHOR]