Self-supporting multi-channel Janus carbon fibers: A new strategy to achieve an efficient bifunctional electrocatalyst for overall water splitting

A new type of self-supporting multi-channel Janus carbon fibers with efficient water splitting has been successfully manufactured using a specially designed parallel spinneret through electrospinning technology and subsequent carbonization technique. Every single Janus fiber composes of a half side of Mo2C and the other half side of Ni components as Mo2C, Ni embedded in N-doped multi-channel Janus carbon fibers ([Mo2C/C]//[Ni/C]-NMCFs) for overall water splitting. Under optimized condition, the hydrogen evolution reaction overpotential of [Mo2C/C]//[Ni/C]-NMCFs (62 mV) is just 24 mV higher than 20 wt% Pt/C (38 mV) at a current density of 10 mA cm-2. Furthermore, it achieves current density of 10 mA cm-2 to require an overpotential of 324 mV for oxygen evolution reaction. Additionally, the cell assembled by the identical [Mo2C/C]//[Ni/C]-NMCFs catalyst as both the cathode and anode needs only 1.607 V at a current density of 10 mA cm-2, which is only 0.022 V higher than that of Pt/C-IrO2 electrodes. Moreover, [Mo2C/C]//[Ni/C]-NMCFs catalyst also exhibits a long-term stability. The synergistic effect and unique heterostructure of Mo2C and Ni enhance the catalytic activity.

A Laser-Induced Mo2 CTx MXene Hybrid Anode for High-Performance Li-Ion Batteries

MXenes, a fast-growing family of two-dimensional (2D) transition metal carbides/nitrides, are promising for electronics and energy storage applications. Mo2 CTx MXene, in particular, has demonstrated a higher capacity than other MXenes as an anode for Li-ion batteries. Yet, such enhanced capacity is accompanied by slow kinetics and poor cycling stability. Herein, it is revealed that the unstable cycling performance of Mo2 CTx is attributed to the partial oxidation into MoOx with structural degradation. A laser-induced Mo2 CTx /Mo2 C (LS-Mo2 CTx ) hybrid anode has been developed, of which the Mo2 C nanodots boost redox kinetics, and the laser-reduced oxygen content prevents the structural degradation caused by oxidation. Meanwhile, the strong connections between the laser-induced Mo2 C nanodots and Mo2 CTx nanosheets enhance conductivity and stabilize the structure during charge-discharge cycling. The as-prepared LS-Mo2 CTx anode exhibits an enhanced capacity of 340 mAh g-1 vs 83 mAh g-1 (for pristine) and an improved cycling stability (capacity retention of 106.2% vs 80.6% for pristine) over 1000 cycles. The laser-induced synthesis approach underlines the potential of MXene-based hybrid materials for high-performance energy storage applications.

Controlled synthesis of Mo2C micron flowers via vapor-liquid-solid method as enhanced electrocatalyst for hydrogen evolution reaction

Mo2C demonstrates excellent performance in catalysis, and it has been found to possess excellent hydrogen evolution reaction (HER) catalytic activity and highly efficient nitrogen fixation. The catalytic activity of Mo2C is greatly influenced and restricted by the preparation method. Sintering and carbon deposition, which affect the catalytic activity of Mo2C, are inevitable in the traditional vapor-solid-solid (VSS) process. In this study, we report the controllable synthesis of α-Mo2C micron flowers by adjusting the growth temperature via a vapor-liquid-solid (VLS) process. The density of the Mo2C micron flowers is closely related to the concentration of Na2MoO4 aqueous solution. The as-grown Mo2C micron flowers dispersed with Pt are validated to be an enhanced collaborative electrocatalyst for HER against Pt/VSS-Mo2C.

A Ni-doped Mo2C/NCF composite for efficient electrocatalytic hydrogen evolution

Ni-Mo₂C nano catalysts dispersed on N-doped carbon flowers: a composite with nitrogen-containing carbon flowers carrying nickel-modified molybdenum carbide exhibits enhanced HER catalytic activity in alkaline electrolyte.

Supported Nanostructured MoxC Materials for the Catalytic Reduction of CO2 through the Reverse Water Gas Shift Reaction

Mo_xC-based catalysts supported on γ-Al₂O₃, SiO₂ and TiO₂ were prepared, characterized and studied in the reverse water gas shift (RWGS) at 548-673 K and atmospheric pressure, using CO₂:H₂ = 1:1 and CO₂:H₂ = 1:3 mol/mol reactant mixtures. The support used determined the crystalline Mo_xC phases obtained and the behavior of the supported nanostructured Mo_xC catalysts in the RWGS. All catalysts were active in the RWGS reaction under the experimental conditions used; CO productivity per mol of Mo was always higher than that of unsupported Mo₂C prepared using a similar method in the absence of support. The CO selectivity at 673 K was above 94% for all the supported catalysts, and near 99% for the SiO₂-supported. The Mo_xC/SiO₂ catalyst, which contains a mixture of hexagonal Mo₂C and cubic MoC phases, exhibited the best performance for CO production.

Iron Catalyzed Cascade Construction of Molybdenum Carbide Heterointerfaces for Understanding Hydrogen Evolution

The intercrystalline interfaces have been proven vital in heterostructure catalysts. However, it is still challenging to generate specified heterointerfaces and to make clear the mechanism of a reaction on the interface. Herein, this work proposes a strategy of Fe-catalyzed cascade formation of heterointerfaces for comprehending the hydrogen evolution reaction (HER). In the pure solid-phase reaction system, Fe catalyzes the in situ conversion of MoO₂ to MoC and then Mo₂ C, and the consecutive formation leaves lavish intercrystalline interfaces of MoO₂ -MoC (in Fe-MoO₂ /MoC@NC) or MoC-Mo₂ C (in Fe-MoC/β-Mo₂ C@NC), which contribute to HER activity. The improved HER activity on the interface leads to further checking of the mechanism with density functional theory calculation. The computation results reveal that the electroreduction (Volmer step) produced H* prefers to be adsorbed on Mo₂ C; then two pathways are proposed for the HER on the interface of MoC-Mo₂ C, including the single-molecular adsorption pathway (Rideal mechanism) and the bimolecular adsorption pathway (Langmuir-Hinshelwood mechanism). The calculation results further show that the former is favorable, and the reaction on the MoC-Mo₂ C heterointerface significantly lowers the energy barriers of the rate-determining steps.

Hierarchical Mo2C@CNT Hybrid Structure Formation for the Improved Lithium-Ion Battery Storage Performance

2-D transition metal carbides (TMCs)-based anode materials offer competitive performance in lithium-ion batteries (LIBs) owing to its excellent conductivity; cheaper, flexible uses; and superior mechanical stability. However, the electrochemical energy storage of TMCs is still the major obstacle due to their modest capacity and the trends of restacking/aggregation. In this report, the Mo₂C nanosheets were attached on conductive CNT network to form a hierarchical 2D hybrid structure, which not only alleviated the aggregation of the Mo₂C nanoparticle and facilitated the rapid transference of ion/electron, but also adapted effectually to the hefty volume expansion of Mo₂C nanosheets and prevented restacking/collapse of Mo₂C structure. Benefitting from the layered Mo₂@CNT hybrid structure, the charge/discharge profile produced a 200 mAh g⁻¹ discharge-specific capacity (second cycle) and 132 mAh g⁻¹ reversible-discharge discharge-specific capacity (after 100 cycles) at 50 mA g⁻¹ current density, with high-speed competency and superior cycle stability. The improved storage kinetics for Mo₂@CNT hybrid structure are credited to the creation of numerous active catalytic facets and association reaction between the CNT and Mo₂C, promoting the efficient electron transfer and enhancing the cycling stability.

Molybdenum Carbide Buried in D-Shaped Fibers as a Novel Saturable Absorber Device for Ultrafast Photonics Applications

Study of nonlinear laser-matter interactions in 2D materials has promoted development of photonics applications. As a typical MXene material, molybdenum carbide (Mo₂C) has attracted much attention because of its graphene-like structure. Here, a type of D-shaped fiber (DF)-buried Mo₂C saturable absorber (SA) fabricated by magnetron-sputtering deposition (MSD) and sol-gel technique is reported. The Mo₂C material was buried between the bottom DF and the upper amorphous silica fabricated by sol-gel technology. Therefore, the DF-based SA effectively solves the problem of material shedding and aging, thus improving the stability and damage threshold of the fiber laser. Application of the SA in erbium-doped fiber laser and stable passive Q-switched operation with a maximum pulse energy of 430.47 nJ is realized. By adjusting the polarization state and pump power, high-power mode-locked pulses are generated with a pulse duration and output power of 199 fs and 54.13 mW, respectively. Further, bound-state soliton pulses are obtained with a pulse width of 312 fs and soliton interval of 1.26 ps for the first time based on MXene materials. Moreover, by application of the SA in ytterbium-doped fiber lasers, a stable dissipative soliton mode-locked pulse is obtained with a pulse width of 23 ps. These results indicate that the DF-based buried Mo₂C as a novel SA provides a reliable method for all-fiber and multifunctional high-power ultrafast laser.

MOF-derived hollow NiCo2O4 nanowires as stable Li-ion battery anodes

Although binary metal oxides with high theoretical specific capacities and power densities are widely investigated as promising anode materials for lithium-ion batteries (LIBs), their poor cycling stability and huge volume expansion largely limit their extensive application in practical electrode materials. Herein, we report a facile strategy to synthesize hollow NiCo2O4 nanowires through direct calcination of binary metal-organic frameworks (MOFs) in air. When evaluated as an anode material for LIBs, NiCo2O4 nanowires deliver a reversible capacity of 1310 mA h g-1 at a current density of 100 mA g-1 after 100 cycles. Even at a high current density of 1 A g-1, NiCo2O4 nanowires exhibit long-term cycling stability with a capacity of 720 mA h g-1 after 1000 cycles. The outstanding lithium-storage performance can be attributed to the unique structures with 1D porous channels, which are beneficial for the fast transfer of Li+ ions and electrolyte and alleviate the strain caused by the volume expansion during cycling processes.

Heterocarbides Reinforced Electrochemical Energy Storage

The feasibility of transition metal carbides (TMCs) as promising high-rate electrodes is still hindered by low specific capacity and sluggish charge transfer kinetics. Improving charge transport kinetics motivates research toward directions that would rely on heterostructures. In particular, heterocomposing with carbon-rich TMCs is highly promising for enhancing Li storage. However, due to limited synthesis methods to prepare carbon-rich TMCs, understanding the interfacial interaction effect on the high-rate performance of TMCs is often neglected. In this work, a novel strategy is proposed to construct a binary carbide heteroelectrode, i.e. incorporating the carbon-rich TMC (M=Mo) with its metal-rich TMC nanowires (nws) via an ingenious in situ disproportionation reaction. Results show that the as-prepared MoC-Mo₂ C-heteronanowires (hnws) electrode could fully recover its capacity after high-rates testing, and also possesses better lithium accommodation performance. Kinetic analysis verified that both electron and ion transfer in MoC-Mo₂ C-hnws are superior to those of its singular counterparts. Such improvements suggest that by taking utilization of the interfacial component interactions of stoichiometry tunable heterocarbides, the electrochemical performance, especially high-rate capability of carbides, could be significantly enhanced.

In Situ Synthesis of MoC1- x Nanodot@Carbon Hybrids for Capacitive Lithium-Ion Storage

In this study, in situ synthesis of carbon-coated MoC_{1- x} nanodots anchored on nitrogen-doped carbon (MoC_{1- x}@C) for lithium storage is reported. The obtained MoC_{1- x}@C hybrids exhibit intriguing structural characteristics including ultrafine particle size (ca. 1.2 nm) of MoC_{1- x} nanodots, porous structure of nitrogen-doped carbon matrix, and good robustness. When evaluated as anodes for lithium-ion batteries, the optimized MoC_{1- x}@C sample demonstrates a superior specific capacity (1099.2 mA h g^-1 at 0.1 A g^-1) and good rate capability (369.1 mA h g^-1 at 5 A g^-1). The MoC_{1- x}@C anode also presents remarkable cycling stability with a much higher specific capacity (657.9 mA h g^-1) than that of commercial bulk MoC (91.4 mA h g^-1) after 500 cycles at 1 A g^-1. Kinetics analysis of the anodes reveals the charge storage mechanism, which demonstrates the existence of capacitive redox reactions occurring at the shallow surface of the MoC_{1- x} nanodots and closely relating to the particle size. The outstanding electrochemical performance results from the synergistic effect of the elastic carbonaceous encapsulation to accommodate the huge volume expansion and the ultrafine MoC_{1- x} nanodots to provide more reactive sites for capacitive lithium storage.

Achieving High-Temperature Stability of Metastable α-MoC1-x by Suppressing Phase Transformation with Mounted Atoms for Lithium Storage Performance

Despite a significant advancement in preparing metastable materials, one common problem is the strict and precious reaction conditions due to their metastable structures. Herein, we achieved the preparation of high-temperature stabilized metastable α-MoC_1-x by mounting zinc atoms into its lattice structure. Such a structural construction could suppress the phase transformation from α-MoC_1-x to β-Mo₂ C through restricting the displacement of Mo atoms upon increased temperature. The resultant metastable α-MoC_1-x can be stabilized up to 1000 °C and this stability temperature is the highest for the metastable α-MoC_1-x so far. Synchrotron X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) confirm the structure of Zn-mounted α-MoC_1-x . Density functional theory (DFT) calculations reveal that the introduction of the Zn atoms in the lattice structure of α-MoC_1-x could significantly decrease the energy difference (ΔE) between α-MoC_1-x and β-Mo₂ C, thus effectively suppressing the phase transformation from α-MoC_1-x to β-Mo₂ C and accordingly maintaining the high-temperature stability of α-MoC_1-x . This novel strategy can be used as a universal method to be extended to synthesize metastable α-MoC_1-x from different precursors or other mounted elements. Moreover, the optimal product exhibits excellent lithium storage performances in terms of the cycling stability and rate performance.

Facile synthesis of porous Mo2C/C composites by using luffa sponge-derived carbon template in molten salt media

Herein, we report the synthesis of a new type of porous Mo2C/C composite by using luffa sponge-derived carbon template and ammonium molybdate ((NH4)6Mo7O24•4H2O) in molten NaCl-KCl salt media. The product exhibits a higher specific surface area and three-dimensional porous structure, including macrochannels, micropores and mesopores. The desirable porous structure results from the carbon template structure and Mo2C coating formed.

Accurate detection of intracellular microRNAs using functional Mo2C quantum dots nanoprobe

A functionalized Mo₂C quantum dots nanoprobe was developed for accurate detection of intracellular mature microRNAs.

Constructing multi-interface Mo2C/Co@C nanorods for a microwave response based on a double attenuation mechanism

In this work, novel one-dimensional (1D) Mo2C/Co@C nanorods (MCRs), using a metal-organic framework (zeolitic imidazolate framework; ZIF-67) as the coating layer to form multi-interfaces, were formed via a facile hard template method. Compared with previous works relating to porous-carbon-based Mo2C nanocomposites, the well-designed MCRs in this study possess a double attenuation mechanism due to the existence of the dielectric materials Mo2C and remaining carbon (RC) and the magnetic compound Co. Thanks to a new design and the multiple useful compounds, the as-prepared MCRs have the features of demonstrating multi-interfacial polarization, a large surface area and highly isotropic dissipation. Hence, the samples not only inherit the excellent microwave absorbing abilities of Mo2C but they also have a broadened effective bandwidth. For example, the minimum reflection loss (RL) value of MCRs with 35% sample loading could reach -47.98 dB. More importantly, RL values of less than -10 dB can be observed from 11.08 to 17.08 GHz (an effective bandwidth of 6.0 GHz) with a matching thickness of 1.6 mm, which is much better than previous work involving porous-carbon-based Mo2C nanocomposites. Firstly, we have reasonably redesigned the samples to have good absorbing properties for practical applications. Secondly, we have paved a highly efficient and universal way to synthesize 1D microwave absorbers with multiple valuable interfaces.

Enhanced kinetics of polysulfide redox reactions on Mo2C/CNT in lithium-sulfur batteries

Among different energy storage devices, the lithium-sulfur (Li-S) battery is the subject of recent attention. However, the capacity decay caused by polysulfide shuttle leading to sluggish kinetics of polysulfide redox reactions is the main hindrance for its practical application in Li-S batteries. Herein, molybdenum carbide nanoparticles anchored on carbon nanotubes (Mo₂C/CNT) are reported to serve as an efficient cathode material to enhance the electrochemical kinetics of polysulfide conversion in Li-S batteries. Mo₂C/CNT shows strong adsorption and activation of polar polysulfides and therefore accelerates the redox kinetics of polysulfides, reduces the energy barrier, effectively mitigates the polarization and polysulfide shuttle, thus improving the electrochemical performance. The S-Mo₂C/CNT composite with 70 wt% sulfur loading exhibits high specific discharge capacity (1206 mA h g^-1 at 0.5 C), excellent high-rate performance, long cycle life (900 cycles), and outstanding Coulombic efficiency (∼100%) at a high rate (2 C) corresponding to a capacity decay of only 0.05%. Remarkably, the S-Mo₂C/CNT cathode with high areal sulfur loading of 2.5 mg cm^-2 exhibits high-rate capacities and stable cycling performance over 100 cycles, offering the potential for use in high energy Li-S batteries.

Porous-carbon-based Mo2C nanocomposites as excellent microwave absorber: a new exploration

In this study, we report a porous-carbon-based Mo2C nanocomposite (NCs) as the microwave absorber via typical carbothermal reduction using metal-organic frameworks (MOFs) and polyoxometalates (POMs) as the precursors, which have been rarely applied in electromagnetic (EM) wave absorption areas. The elaborately designed NCs not only bring about good impedance matching, but also possess strong dissipation ability due to the large surface areas and porous features. Thanks to the material characteristics as well as structural advantages, the as-prepared Mo2C/C NCs with 20 wt% sample loading exhibit remarkable microwave absorbing performance. The minimum RL value reaches -49.19 dB at matching thickness of 2.6 mm, and the best effective bandwidth (RL < -10 dB) of 4.56 GHz at 1.70 mm was also achieved. Moreover, the NCs overcome the intrinsic drawback of traditional carbon materials, that is, centralized effective absorption always occurred at high frequency (>10 GHz) and the minimum RL value of the NCs shifted to 9.04 GHz. Clearly, in this study, we not only developed the Mo2C NC as the new light absorber, but also paved the way to synthesize other available transition metal carbides using MOFs and POMs.

Decorating carbon nanofibers with Mo2C nanoparticles towards hierarchically porous and highly catalytic cathode for high-performance Li-O2 batteries

A facile synthesis of the hierarchically porous cathode with Mo₂C nanoparticles through the electrospinning technique and heat treatment is proposed. The carbonization temperature of the precursors is the key factor for the formation of Mo₂C nanoparticles on the carbon nanofibers (MCNFs). Compared with the Mo₂N nanoparticles embedded into N-doped carbon nanofibers film (MNNFs) and N-doped carbon nanofibers film (NFs), the battery with MCNFs cathode is capable of operation with a high-capacity (10,509 mAh g^-1 at 100 mA g^-1), a much reduced discharge-charge voltage gap, and a long-term life (124 cycles at 200 mA g^-1 with a specific capacity limit of 500 mAh g^-1). These excellent performances are derived from the synergy of the following advantageous factors: (1) the hierarchically self-standing and binder-free structure of MCNFs could ensure the high diffusion flux of Li⁺ and O₂ as well as avoid clogging of the discharge product, bulk Li₂O₂; (2) the well dispersed Mo₂C nanoparticles not only afford rich active sites, but also facilitate the electronic transfer for catalysis.

Molybdenum Carbide-Decorated Metallic Cobalt@Nitrogen-Doped Carbon Polyhedrons for Enhanced Electrocatalytic Hydrogen Evolution

Electrocatalytic hydrogen evolution reaction (HER) based on water splitting holds great promise for clean energy technologies, in which the key issue is exploring cost-effective materials to replace noble metal catalysts. Here, a sequential chemical etching and pyrolysis strategy are developed to prepare molybdenum carbide-decorated metallic cobalt@nitrogen-doped porous carbon polyhedrons (denoted as Mo/Co@N-C) hybrids for enhanced electrocatalytic hydrogen evolution. The obtained metallic Co nanoparticles are coated by N-doped carbon thin layers while the formed molybdenum carbide nanoparticles are well-dispersed in the whole Co@N-C frames. Benefiting from the additionally implanted molybdenum carbide active sites, the HER performance of Mo/Co@N-C hybrids is significantly promoted compared with the single Co@N-C that is derived from the pristine ZIF-67 both in alkaline and acidic media. As a result, the as-synthesized Mo/Co@N-C hybrids exhibit superior HER electrocatalytic activity, and only very low overpotentials of 157 and 187 mV are needed at 10 mA cm^-2 in 1 m KOH and 0.5 m H₂ SO₄ , respectively, opening a door for rational design and fabrication of novel low-cost electrocatalysts with hierarchical structures toward electrochemical energy storage and conversion.

Flexible C–Mo2C fiber film with self-fused junctions as a long cyclability anode material for sodium-ion battery

Fiber junctions were fused by introducing MoO₂, that eliminates the contact resistance at fiber junctions, and significantly improves the cyclability.

Electrochemically Synthesized Nanoporous Molybdenum Carbide as a Durable Electrocatalyst for Hydrogen Evolution Reaction

Demands for sustainable production of hydrogen are rapidly increasing because of environmental considerations for fossil fuel consumption and development of fuel cell technologies. Thus, the development of high-performance and economical catalysts has been extensively investigated. In this study, a nanoporous Mo carbide electrode is prepared using a top-down electrochemical process and it is applied as an electrocatalyst for the hydrogen evolution reaction (HER). Anodic oxidation of Mo foil followed by heat treatment in a carbon monoxide (CO) atmosphere forms a nanostructured Mo carbide with excellent interconnections, and these structural characteristics lead to high activity and durability when applied to the HER. Additionally, characteristic behavior of Mo is observed; metallic Mo nanosheets form during electrochemical anodization by exfoliation along the (110) planes. These nanosheets are viable for chemical modification, indicating their feasibility in various applications. Moreover, the role of carbon shells is investigated on the surface of the electrocatalysts, whereby it is suggested that carbon shells serve as a mechanical barrier against the oxidative degradation of catalysts that accompanies unavoidable volume expansion.

Various Structured Molybdenum-based Nanomaterials as Advanced Anode Materials for Lithium ion Batteries

A facile and scalable solvothermal high-temperature treatment strategy was developed to construct few-layered ultrasmall MoS₂ with less than three layers. These are embedded in carbon spheres (MoS₂-C) and can be used as advanced anode material for lithium ion batteries (LIBs). In the resulting architecture, the intimate contact between MoS₂ surface and carbon spheres can effectively avert aggregation and volume expansion of MoS₂ during the lithiation-delithiation process. Moreover, it improves the structural integrity of the electrode remarkably, while the conductive carbon spheres provide quick transport of both electrons and ions within the electrode. Benefiting from this unique structure, the resulting hybrid manifests outstanding electrochemical performance, including an excellent rate capability (1085, 885, and 510 mAh g^-1 at 0.5, 2, and 5 A g^-1), and a superior cycling stability at high rates (maintaining 100% of the initial capacity following 500 cycles at 0.5 A g^-1). Using identical methods, molybdenum carbide and phosphide supported on carbon spheres (Mo₂C-C, and MoP-C) were prepared for LIBs. As a result, MoS₂-C exhibits outstanding lithium storage capacities due to its specific layered structure. This study investigates large-scale production capabilities of few-layered structure ultrasmall MoS₂ for energy storage, and thoroughly compares lithium storage performance of molybdenum compounds.

Highly Conductive Mo2C Nanofibers Encapsulated in Ultrathin MnO2 Nanosheets as a Self-Supported Electrode for High-Performance Capacitive Energy Storage

Nanostructured transition metal carbides (TMCs) with superior electrochemical properties are promising materials for high-efficiency energy-storage applications. Herein one-dimensional molybdenum carbide nanofibers (Mo₂C NFs) have been fabricated by a facile and effective electrospinning strategy. Based on the cross-linked network architecture with ultrahigh electronic conductivity, each Mo₂C NF is uniformly encapsulated in lamellar manganese dioxide (MnO₂) via electrodeposition, forming a self-supported MnO₂-Mo₂C NF film with excellent electrochemical activity. Remarkably, the highly conductive inner layer of porous Mo₂C NFs acts like a "highway" to facilitate charge transport and ionic diffusion, while the MnO₂ nanosheets with abundant active area are favorable for the accumulation of effective electric charges. Benefiting from these features, the hybrid film is directly applied as the self-standing electrode of supercapacitors (SCs) without any additives, which delivers considerably large specific capacitance with strong durability in both aqueous and organic (ionic liquid) electrolytes. This work elucidates a feasible way toward heteronanofiber engineering of TMCs on a promising additive-free electrode for flexible and high-performance SCs.

Ultra-efficient electrocatalytic hydrogen evolution at one-step carbonization generated molybdenum carbide nanosheets/N-doped carbon

The hydrogen evolution reaction (HER) from water through electrocatalysis using highly active noble metal-free catalysts as an alternative to precious Pt-based catalysts holds great promise for clean and renewable energy systems. Here, Mo₂C nanosheets well-regulated in N-doped carbon (MCNS/NC)are facilely achieved by in situ confining carburization of a Mo-based inorganic-organic lamellar mesostructure at 900 °C, and demonstrated for the first time as an ultra-efficient and durable HER catalyst. The MCNS/NC displays a very low onset overpotential of ∼0 mV and an overpotential of 19 mV at 10 mA cm^-2 with a small Tafel slope of 28.9 mV dec^-1 in acid media, which is remarkably superior to most other transition metal-based catalysts and comparable to commercial Pt/C. The HER kinetics are further studied by EIS and Tafel slope analysis, suggesting the dominant Volmer-Tafel mechanism. An "outside-in" carburization mechanism for the evolution of MCNS/NC is proposed through detailed investigation of the samples annealed at different temperatures. This study highlights the importance of designing well-regulated functional nanostructures combined with a conductive carbonaceous matrix for versatile applications.

Versatile fabrication of a superhydrophobic and ultralight cellulose-based aerogel for oil spillage clean-up

To deal with marine oil spillage and chemical leakage issues, a highly efficient absorbent (cellulose based aerogel) with a low density (ρ < 0.034 g cm⁻³, φ > 98.5%) and high mechanical strength was fabricated via a novel physical–chemical foaming method, plasma treatment and subsequent silane modification process.