Abstract
Rational regulation of electrochemical reconfiguration and exploration of activity origin are important foundations for realizing the optimization of electrocatalyst activity, but rather ...challenging. Herein, we potentially develop a rapid complete reconfiguration strategy for the heterostructures of CoC
2
O
4
coated by MXene nanosheets (CoC
2
O
4
@MXene) during the hydrogen evolution reaction (HER) process. The self-assembled CoC
2
O
4
@MXene nanotubular structure has high electronic accessibility and abundant electrolyte diffusion channels, which favor the rapid complete reconfiguration. Such rapid reconfiguration creates new actual catalytic active species of Co(OH)
2
transformed from CoC
2
O
4
, which is coupled with MXene to facilitate charge transfer and decrease the free energy of the Volmer step toward fast HER kinetics. The reconfigured components require low overpotentials of 28 and 216 mV at 10 and 1000 mA cm
−2
in alkaline conditions and decent activity and stability in natural seawater. This work gives new insights for understanding the actual active species formation during HER and opens up a new way toward high-performance electrocatalysts.
Metal single‐atom materials with their high atom utilization efficiency and unique electronic structures usually show remarkable catalytic performances in many crucial chemical reactions. Herein, a ...facile and easily scalable “impregnation‐carbonization‐acidification” strategy for fabricating a class of single‐atom‐anchored (including cobalt and nickel single atoms) monolith as superior binder‐free electrocatalysts for developing high‐performance wearable Zn–air batteries is reported. The as‐prepared single atoms, supported by N‐doped carbon flake arrays grown on carbon nanofibers assembly (M SA@NCF/CNF), demonstrate the dual characteristics of excellent catalytic activity (reversible oxygen overpotential of 0.75 V) and high stability, owing to the greatly improved active sites' accessibility and optimized single‐sites/pore‐structures correlations. Furthermore, wearable Zn–air battery based on Co SA@NCF/CNF air electrode displays superior stability under deformation, satisfactory energy storage capacity, and good practicality to be utilized as an integrated battery system. Theoretical calculations reveal a mechanism for the promotion of the catalytic performances on single atomic sites by lowering the overall oxygen reduction/evolution reaction barriers comparing to metal cluster co‐existing configuration. These findings provide a facile strategy for constructing free‐standing single‐atom materials as well as the engineering of high‐performance binder‐free catalytic electrodes.
A class of single‐atom‐anchored hierarchically porous monoliths for flexible energy storage is prepared by a facile and easily scalable “impregnation–carbonization–acidification” strategy. It exhibits excellent bifunctional electrocatalytic activity for oxygen reduction/evolution reactions. Wearable zinc–air batteries based on this binder‐free monolith show low overpotential and high mechanical stability.
Tissue regeneration, energy conversion & storage, and water treatment are some of the most critical challenges facing humanity in the 21st century. In order to address such challenges, ...one-dimensional (1D) materials are projected to play a key role in developing emerging solutions for the increasingly complex problems. Eletrospinning technology has been demonstrated to be a simple, versatile, and cost-effective method in fabricating a rich variety of materials with 1D nanostructures. These include polymers, composites, and inorganic materials with unique chemical and physical properties. In this tutorial review, we first give a brief introduction to electrospun materials with a special emphasis on the design, fabrication, and modification of 1D functional materials. Adopting the perspective of chemists and materials scientists, we then focus on the recent significant progress made in the domains of tissue regeneration (
e.g.
, skin, nerve, heart and bone) and conversion & storage of clean energy (
e.g.
, solar cells, fuel cells, batteries, and supercapacitors), where nanofibres have been used as active nanomaterials. Furthermore, this review's scope also includes the advances in the use of electrospun materials for the removal of heavy metal ions, organic pollutants, gas and bacteria in water treatment applications. Finally a conclusion and perspective is provided, in which we discuss the remaining challenges for 1D electrospun nanomaterials in tissue regeneration, energy conversion & storage, and water treatment.
This
Tutorial Review
focuses on recent applications of electrospun materials in tissue regeneration, energy conversion & storage, and water treatment areas.
Developing efficient bifunctional electrocatalysts toward oxygen/hydrogen evolution reactions is crucial for electrochemical water splitting toward hydrogen production. The high‐performance ...electrocatalysts depend on the catalytically active and highly accessible reaction sites and their structural robustness, while the rational design of such electrocatalysts with desired features avoiding tedious manufacture is still challenging. Here, a facile method is reported to synthesize mesoporous and heterostructured transition metal oxides strongly anchored on a nickel skeleton (MH‐TMO) containing identified Fe–Cu oxide interfaces with high intrinsic activity, easy accessibility for reaction intermediates, and long‐term stability for alkaline oxygen/hydrogen evolution reactions. The MH‐TMO with the electrocatalytically active Fe–O–Cu bridge has an optimal oxygen binding energy to facilitate adsorption/desorption of oxygen intermediates for oxygen molecules. Associated with the high mass transport through the nanoporous structure, MH‐TMO exhibits impressive oxygen evolution reaction catalysis, with an extremely low overpotential of around 0.22 V at 10 mA cm−2 and low Tafel slope (44.5 mV dec−1) in 1.0 M KOH, realizing a current density of 100 mA cm−2 with an overpotential as low as 0.26 V. As a result, the alkaline electrolyzer assembled by the bifunctional MH‐TMO catalysts operates with an outstanding overall water‐splitting output (1.49 V@10 mA cm−2), outperforming one assembled with noble‐metal‐based catalysts.
A facile method based on a lattice‐matching strategy is reported to synthesize Fe–Cu oxides with high mesoporosity and unique heterostructure. The established structure possesses high activity for the oxygen evolution reaction with an extremely low overpotential of around 0.22 V at 10 mA cm−2 as well as electrocatalytic bifunctionality for high‐performance water splitting with an outstanding overall output (1.49 V@10 mA cm−2).
Electrospinning has received tremendous attention in terms of the design and fabrication of 1D nanofibers for oxygen electrocatalysis in fuel cells and metal‐air batteries, owing to their high ...surface area, short charge transport path, superior chemical stability, etc. In this review, a brief introduction is given for fuel cells, metal‐air batteries, and the operation principle of electrospinning. After that, the recent progress of the noble‐metal‐free electrocatalysts prepared through electrospinning, mainly containing heteroatoms‐doped electrospun carbon nanofibers (ECNFs), ECNFs functionalized with transition metal nanoparticles and their compounds (alloy, oxides, carbides, nitrides, sulfides, phosphides), and unique nanostructured transition metal‐nitrogen‐ECNFs (including single‐atom catalysts) are summarized. In this section, electrospun electrodes with self‐standing peculiarity are emphasized. Next, other kinds of electrospun nanofibers based on oxides, nitrides, and carbides as electrocatalysts or their hybrid materials are also discussed. Finally, the prospects and possible future research direction of electrospun NFs‐based oxygen electrocatalysts are also presented. This comprehensive review is anticipated to be valuable and helpful in the context of understanding the design and fabrication of advanced energy conversion and storage devices.
This review covers the design and fabrication of oxygen electrocatalysts toward metal‐air batteries and fuel cells, prepared through electrospinning, that mainly contain heteroatom‐doped electrospun carbon nanofibers (ECNFs), ECNFs functionalized with transition metal nanoparticles and their compounds (alloy, oxides, carbides, nitrides, sulfides, phosphides), and unique nanostructured transition metal‐nitrogen‐ECNFs (including single‐atom catalysts).
Rechargeable aluminum‐ion batteries (AIBs) are considered as a new generation of large‐scale energy‐storage devices due to their attractive features of abundant aluminum source, high specific ...capacity, and high energy density. However, AIBs suffer from a lack of suitable cathode materials with desirable capacity and long‐term stability, which severely restricts the practical application of AIBs. Herein, a binder‐free and self‐standing cobalt sulfide encapsulated in carbon nanotubes is reported as a novel cathode material for AIBs. The resultant new electrode material exhibits not only high discharge capacity (315 mA h g−1 at 100 mA g−1) and enhanced rate performance (154 mA h g−1 at 1 A g−1), but also extraordinary cycling stability (maintains 87 mA h g−1 after 6000 cycles at 1 A g−1). The free‐standing feature of the electrode also effectively suppresses the side reactions and material disintegrations in AIBs. The new findings reported here highlight the possibility for designing high‐performance cathode materials for scalable and flexible AIBs.
Binder‐free and free‐standing cobalt sulfide@carbon nanotubes are applied as the cathode for aluminum‐ion batteries with enhanced electrochemical performance. The optimized electrode exhibits a high capacity (315 mA h g−1 at 100 mA g−1), excellent rate performance, and remarkable cycling stability (297 mA h g−1 at 100 mA g−1 after 200 cycles; 87 mA h g−1 at 1 A g−1 after 6000 cycles).
Hierarchical NiMoO4 architectures assembled from well‐aligned uniform nanosheets or nanorods are successfully grown on various conductive substrates using a facile and effective general approach. ...Importantly, the nanostructures of NiMoO4 can be easily controlled to be nanosheets or nanorods by using different solvents. By virtue of their intriguing structure features, NiMoO4 nanosheets as integrated additive‐free electrodes for supercapacitors manifest higher Faradaic capacitance than NiMoO4 nanorods. Moreover, an asymmetric supercapacitor (ASC) is constructed using the as‐prepared NiMoO4 nanosheets as the positive electrode and activated carbon (AC) as the negative electrode. The optimized ASC with an extended operating voltage range of 0–1.7 V displays excellent electrochemical performance with a high energy density of 60.9 Wh kg−1 at a power density of 850 W kg−1 in addition to superior rate capability. Furthermore, the NiMoO4//AC ASC device exhibits remarkable cycling stability with 85.7% specific capacitance retention after 10 000 cycles. The results show that these NiMoO4‐based nanostructures are promising for high‐energy supercapacitors.
Hierarchical NiMoO4 nanosheet and nanorod arrays are successfully grown on various conductive substrates using a facile and effective solution method. Combined with activated carbon, the integrated NiMoO4‐Ni foam electrode is successfully used to construct a high‐performance asymmetric supercapacitor that has high energy density and remarkable cycling stability.
Cu2O is a typical photoelectrocatalyst for sustainable hydrogen production, while the fast charge recombination hinders its further development. Herein, Ni2+ cations have been doped into a Cu2O ...lattice (named as Ni‐Cu2O) by a simple hydrothermal method and act as electron traps. Theoretical results predict that the Ni dopants produce an acceptor impurity level and lower the energy barrier of hydrogen evolution. Photoelectrochemical (PEC) measurements demonstrate that Ni‐Cu2O exhibits a photocurrent density of 0.83 mA cm−2, which is 1.34 times higher than that of Cu2O. And the photostability has been enhanced by 7.81 times. Moreover, characterizations confirm the enhanced light‐harvesting, facilitated charge separation and transfer, prolonged charge lifetime, and increased carrier concentration of Ni‐Cu2O. This work provides deep insight into how acceptor‐doping modifies the electronic structure and optimizes the PEC process.
Taking charge: A nickel (Ni) electron acceptor has been successfully doped into a Cu2O lattice without forming impurity phases. Both theoretical and experimental results demonstrate that Ni dopants attract electrons from neighboring atoms, therefore facilitating charge separation and transfer. Consequently, the obtained Ni‐Cu2O exhibits a significantly enhanced photoelectrochemical performance.
Flexible three‐dimensional (3D) nanoarchitectures have received tremendous interest recently because of their potential applications in wearable electronics, roll‐up displays, and other devices. The ...design and fabrication of a flexible and robust electrode based on cobalt sulfide/reduced graphene oxide/carbon nanotube (CoS2/RGO‐CNT) nanocomposites are reported. An efficient hydrothermal process combined with vacuum filtration was used to synthesize such composite architecture, which was then embedded in a porous CNT network. This conductive and robust film is evaluated as electrocatalyst for the hydrogen evolution reaction. The synergistic effect of CoS2, graphene, and CNTs leads to unique CoS2/RGO‐CNT nanoarchitectures, the HER activity of which is among the highest for non‐noble metal electrocatalysts, showing 10 mA cm−2 current density at about 142 mV overpotentials and a high electrochemical stability.
Hybrid composites: The fabrication of a flexible electrode based on cobalt sulfide/reduced graphene/carbon nanotube nanocomposite is reported. The CoS2 nanosheets were self‐assembled on a reduced graphene oxide matrix and then embedded in a porous network of carbon nanotubes. This conductive film showed a superior electrocatalytic activity for the hydrogen evolution reaction (see picture).
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