Simple Pyrolysis Research Articles

Low‐temperature thermal energy storage with polymer‐derived ceramic aerogels

AbstractThermal energy storage (TES) with phase change materials (PCMs) presents some advantages when shape‐stabilization is performed with ceramic aerogels. These low‐density and ultra‐porous materials guarantee high energy density and can be easily regenerated through simple pyrolysis while accounting for moderate mechanical properties. However, the small pore size that typically characterizes these sorbents can hinder the crystallization of PCMs, slightly reducing the energy density of the stabilized compound. In this work, we present the use of polymer‐derived mesoporous SiC and SiOC aerogels for the stabilization of polyethylene glycol and a fatty alcohol (PureTemp 23), having a melting temperature of 17 and 23°C, respectively. Their TES performances point out maximum thermal efficiency values of around 80%. These performances are discussed accounting for the results of thermogravimetric analysis, differential scanning calorimetry, and leaking tests.

Efficient Activation of Peroxymonosulfate by Biochar-Loaded Zero-Valent Copper for Enrofloxacin Degradation: Singlet Oxygen-Dominated Oxidation Process.

Simple SummaryThe misuse of antibiotics has caused ecological and human health risks on a global scale. Peroxymonosulfate can generate reactive oxygen species with extremely strong oxidative properties, which can degrade most types of antibiotics. For efficient removal of antibiotics in the aqueous environment, an economic biochar-loaded zero-valent copper was prepared by a simple pyrolysis method to activate peroxymonosulfate so that it can generate reactive oxygen species to oxidative and degrade the typical antibiotics, enrofloxacin. It was shown that complete degradation of enrofloxacin could be achieved within 30 min using biochar-loaded zero-valent copper to activate peroxymonosulfate, and the process of reactive oxygen species generation and the degradation pathway of enrofloxacin were also revealed.The removal of contaminants of emerging concern (CECs) has become a hot research topic in the field of environmental engineering in recent years. In this work, a simple pyrolysis method was designed to prepare a high-performance biochar-loaded zero-valent copper (CuC) material for the catalytic degradation of antibiotics ENR by PMS. The results showed that 10 mg/L of ENR was completely removed within 30 min at an initial pH of 3, CuC 0.3 g/L, and PMS 2 mmol/L. Further studies confirmed that the reactive oxygen species (ROS) involved in ENR degradation are ·OH, ·, 1O2, and . Among them, 1O2 played a major role in degradation, whereas · played a key role in the indirect generation of 1O2. On the one hand, CuC adsorbed and activated PMS to generate ·OH, · and ·. · was unstable and reacted rapidly with H2O and ·OH to generate large amounts of 1O2. On the other hand, both the self-decomposition of PMS and direct activation of PMS by C=O on biochar also generated 1O2. Five byproducts were generated during degradation and eventually mineralized to CO2, H2O, , and F−. This study provides a facile strategy and new insights into the biochar-loaded zero-valent transition-metal-catalyzed PMS degradation of CECs.

Embedding amorphous MoSx within hierarchical porous carbon by facile one-pot synthesis for superior sodium ion storage

The design of anode materials with a high specific capacity, high cyclic stability, and superior rate performance is required for the practical applications of sodium-ion batteries (SIBs). In this regard, we introduce in this work a facile, low-cost and scalable method for the synthesis of nanocomposites of amorphous molybdenum sulfide (a-MoSx) and hierarchical porous carbon and have systematically investigated their performance for sodium ion storage. In the synthesis, ammonium molybdate tetrahydrate and thioacetamide are used as molybdenum and sulfur sources, respectively, with abundant corn starch as the carbon source and KOH as an activation agent. A simple pyrolysis of their mixtures leads to the formation of nanocomposites with a-MoSx embedded within a hierarchical porous carbon (MoSx@HPC), which are featured with a high surface area of up to 518.4 m2 g−1 and hierarchical pores ranging from micropores to macropores. It has also been shown that the annealing of MoSx@HPC results in the formation of crystalline MoS2 nanosheets anchored in the hierarchical porous carbon matrix (MoS2@HPC). The as-prepared nanocomposite MoSx@HPC1 at an optimum carbon content of 32 wt% delivers a high specific sodium storage capacity of 599 mAh g−1 at 0.2 A g−1 and a high-rate performance with a retained capacity of 289 mAh g−1 at 5 A g−1. A comparison of the electrochemical performances of MoSx@HPC and MoS2@HPC demonstrates the superior specific capacity, rate performance, and charge transfer kinetics of the former, highlighting the unique advantageous role of amorphous MoSx relative to crystalline MoS2.

Porous biochar aerogel loaded PtFe alloys derived from natural marine polysaccharide for efficient oxygen reduction

Lowering the Pt loading of Pt-based materials is a promising strategy to explore excellent oxygen reduction reaction (ORR) electrocatalysts. One surprising approach is to develop Pt-alloys, which can effectively reduce the usage of Pt and induced highly catalytic activity through regulation effect between multimetals. Herein, the N-doped porous biochar aerogel/reduced graphene oxide loaded PtFe alloys (PtFe/NC-rGO (Pt1Fe5)) with low Pt loading (with a Pt content of 7.54 wt%) were prepared using natural marine polysaccharide-alginate as precursor through simple pyrolysis process. The biochar aerogel as an ideal carbon support shows an excellent electrical conductivity as well as a high specific surface area utilized for mass transport together with ion diffusion during ORR. Consequently, the PtFe/NC-rGO (Pt1Fe5) exhibits highly excellent ORR catalytic activity with respect to the pure Pt/NC-rGO together with the commercial Pt/C catalysts, with good half-wave potentials of 0.81 and 0.87 V vs. RHE in 0.5 M H2SO4 as well as 0.1 M KOH solutions, respectively. The strategy gives a new way to construct Pt-based alloy ORR electrocatalysts with low Pt consumption and the easy availability of biomass raw materials for PtFe/NC-rGO ensures its potential for large-scale application.

Catalysts containing Fe and Mn from dewatered sludge showing enhanced electrocatalytic degradation of triclosan

The present work demonstrates a simple one-step pyrolysis method for the synthesis of a catalytic sludge-based carbon (SBC) biochar containing Fe and Mn from dehydrated sludge with added KMnO4 and Fe(II). The electrocatalytic degradation of triclosan (TCS) in water was evaluated using an Fe/Mn-SBC cathode to promote a heterogeneous Fenton-like reaction. The catalyst generated at 500 °C exhibited an abundant porous structure and a relatively high surface area, and produced an electrode with better conductivity and electron diffusion. The presence of metal oxides changed the surface structure defects of this biochar and enhanced its catalytic performance while increasing the electrochemically active surface area by 72.68 mF/cm2 compared with plain SBC. TCS was degraded (91.3%) within 180 min by oxygen species generated in situ on an Fe/Mn-SBC cathode because the activation energy for oxygen reduction was lowered by 4.62 kJ/mol. The degradation of TCS followed pseudo first-order kinetics and was controlled by TCS diffusion and interfacial chemical reactions between adsorbed TCS and the electrode. Possible TCS degradation pathways were devised based on the main intermediates, and 1O2 was found to be more important than •OH radicals. Through toxicity test and prediction, the toxicity of degradation was gradually reduced. This study demonstrates a simple and ecofriendly method for the electrocatalytic degradation of organic pollutants.

An engineering CFD model for fire spread on wood cribs for travelling fires

The temperature heterogeneity due to fire in large open-plan office compartments is closely associated with fire spread behaviour and has been historically limited to experimental investigations using timber cribs. This study explores the ability of Computational Fluid Dynamics (CFD) models, specifically the Fire Dynamics Simulator (FDS), to reproduce the results of full-scale tests involving fire spread over timber cribs for continuous fuel-beds. Mesh schemes are studied, with a fine mesh over the crib and 2 × 2 cells in the wood stick cross-section by default, this being relaxed in the surrounding regions to enhance computational efficiency. The simple pyrolysis model considers the charring phase and moisture. In application to the TRAFIR-Liège LB7 test, this calibrated “stick-by-stick” representation shows a good agreement for interrelated parameters of heat release rate, fire spread, gas phase temperature, and burn-away, a set of agreements which has not been demonstrated in previous studies. Fire spread shows relatively high sensitivities to: heat of combustion, ignition temperature, thermal inertia, radiation fraction, heat release rate per unit area, and the fuel load density. An approximately linear regression was found between the different fire modes and the thermal exposures, with “travelling” (and decaying) fires characterised by heat fluxes associated with the fire plume, while the growing fires were associated with proportionally higher heat fluxes on the horizontal surfaces of the sticks, in conditions where these receive more pre-heating. The trends in the overall HRR are more dependent on the fire spread rates than variations in the stick burning rates.

Wood-derived porous carbon supported γ-Fe2O3 nanoparticles as efficient catalyst for oxygen reduction reaction

The sluggish kinetics of oxygen reduction reaction at the cathode is one of the obstacles of the next-generation energy conversion system such as fuel cell and Zn-air battery. Here, a simple pyrolysis method was used to transform delignification-treated balsa wood into nitrogen-doped porous layered carbon materials. γ-Fe2O3 nanocrystals were supported on N-doped wood-derived carbon materials. The prepared Fe2O3-CW1000 catalyst exhibits superior ORR performance with a high onset potential of 0.98 VRHE in alkaline environment. This is consistent with the potential of commercial Pt/C. The superior ORR activity is attributed to the fact that γ-Fe2O3 nanoparticles promote the activity of Fe-Nx sites. And the N-enriched porous carbon matrix facilitates the faster electron movement on the catalyst surface and the full exposure of the active sites.

Fast Current-Driven Synthesis of ZIF-Derived Catalyst Layers for High-Performance Zn-Air Battery.

As a core component, the catalyst layer (CL) is widely used in fuel cell, metal-air battery, and other energy conversion devices. Herein, a highly efficient method for CL preparation via fast current-driven synthesis followed by pyrolysis is proposed. Compared with previously reported fabrication procedures of zeolite imidazolate frameworks (ZIF)-based CLs, this method directly deposits the ZIF precursor onto the conductive substrate in a very short time (≤15min). The self-supporting CL, converted from ZIF membrane by simple single-step pyrolysis, is assembled with the gas diffusion layer to obtain cathode. Electrochemical tests exhibit a small potential gap (0.83V) between the oxygen reduction and evolution reactions, as well as high performance and excellent stability for Zn-air battery (241mW cm-2 at 390mA cm-2 ), due to the unique design of a bi-continuous framework (interconnected pores and long carbon nanotubes) and Co-based active sites. This work may provide new directions for the fast fabrication of non-platinum group metal CLs for metal-air batteries or fuel cell applications.

Simple Joule-heating pyrolysis in air boosts capacitive performance of commercial carbon fiber cloth

Simple Joule-heating pyrolysis in air boosts capacitive performance of commercial carbon fiber cloth

Enhanced oxygen evolution reaction kinetics through biochar-based nickel-iron phosphides nanocages in water electrolysis for hydrogen production

Highly-efficient and stable non-noble metal electrocatalysts for overcoming the sluggish kinetics of oxygen evolution reaction (OER) is urgent for water electrolysis. Biomass-derived biochar has been considered as promising carbon material because of its advantages such as low-cost, renewable, simple preparation, rich structure, and easy to obtain heteroatom by in-situ doping. Herein, Ni2P–Fe2P bimetallic phosphide spherical nanocages encapsulated in N/P-doped pine needles biochar is prepared via a simple two-step pyrolysis method. Benefiting from the maximum synergistic effects of bimetallic phosphide and biochar, high conductivity of biochar encapsulation, highly exposed active sites of Ni2P–Fe2P spherical nanocages, rapid mass transfer in porous channels with large specific surface area, and the promotion in adsorption of reaction intermediates by high-level heteroatom doping, the (Ni0.75Fe0.25)2P@NP/C demonstrates excellent OER activity with an overpotential of 250 mV and a Tafel slope of 48 mV/dec at 10 mA/cm2 in 1 M KOH. Also it exhibits a long-term durability in 10 h electrolysis and its activity even improves during the electrocatalytic process. The present work provides a favorable strategy for the inexpensive synthesis of biochar-based transition metal electrocatalysts toward OER, and improves the water electrolysis for hydrogen production.

Super broadband absorbing hierarchical CoFe alloy/porous carbon@carbon nanotubes nanocomposites derived from metal-organic frameworks

The exploitation of electromagnetic wave absorption (EMA) materials has attracted ever-increasing attention, not only because electromagnetic wave (EMW) originated from overuse of electronic products has threatened human’ health seriously, but also because EMA materials can effectively protect radar stealth from being detected. However, it is still a challenge to obtain broadband and efficient EMA materials to satisfy practical applications. In this work, we developed a series of hierarchical CoFe alloy/porous [email protected] nanotubes (CoFe/[email protected]) nanocomposites through revising the proportion of Fe2+ in the metal-organic frameworks (MOFs) (CoFe-ZIF) precursor and one-step simple pyrolysis process. The cross deposition between CoFe alloy, carbon nanotubes (CNTs), and porous carbon (PC) formed a double conductive network, favoring for achieving excellent EMA property. Surprisingly, when the filler mass ratio is only 10 wt%, the optimized CoFe/[email protected] nanocomposites display the best EMA capability, whose minimum reflection loss (RLmin) value is –68.94 dB at 13.69 GHz and the effective absorption band (EAB, < –10 dB) reaches up 9.14 GHz with a matching thickness of 2.63 mm. In addition, the largest EAB can achieve up to 11 GHz (3.35–14.35 GHz) during all matching thicknesses. The splendid EMA performance benefits the favorable dielectric loss provided by the double conductive network, the good magnetic loss benefited from the evenly distributed CoFe alloy, the excellent impedance matching, rich transmission paths, and multiple polarization. Therefore, such EMA materials with super broadband absorbing provide desirable candidates for lightweight and high-efficient microwave absorbers.

Solvent-free conversion of cucumber peels to N-doped microporous carbons for efficient CO2 capture performance

For the first time, cucumber peel (CP) biomass was used to produce a novel three-dimensional (3D) carbon precursor using simple pyrolysis. The carbon precursor was then converted into a series of N-doped microporous carbons using a facile solvent-free process involving a chemical agent and melamine. A solvent-free process is an effective approach because it does not require hazardous solvents, several complex steps, and high costs. The optimized sample (CP–K-900) has a high CO2 adsorption capacity (7.3 mmol g−1 at 273 K and 1 bar) because it has (i) excellent textural features (a high specific surface area (SSA) of 2682 m2 g−1, large micropore volume of 1.01 cm3 g−1, and high concentration (65.1%) of narrow micropores (<0.7 nm)), high degree of graphitization, and (ii) a feasible concentration of self-doped N and O contents. According to our experimental results, porous textural features is more imperative for high CO2 uptakes than high N-doping contents. A micropore size of less than 1 nm produced the best-fit linear relationship with CO2 capture at 273 K. Furthermore, the optimized material has an intermediate isosteric heat of adsorption (46.4 kJ mol−1), indicating the physisorption nature of the adsorption process. The excellent regeneration ability of microporous carbons over six consecutive adsorption-desorption cycles under flue gas conditions (15%CO2/85%N2) revealed the potential of as-designed cost-effective and feasible microporous carbonaceous materials for efficient practical environmental remediation applications.

Hierarchical macro-mesoporous electrocatalysts with dual-active sites of Ru single atoms and monodispersed Ru–Mo nanoclusters for efficient hydrogen evolution

Rationally designing high-performance electrocatalysts with high density and multiactive sites is an effective strategy to accelerate the alkaline hydrogen evolution reaction (HER) kinetics, yet it remains challenging. Herein, a catalyst comprising numerous Ru–Mo-based single atoms and subnanoclusters incorporated into a hierarchical macro-mesoporous carbon framework with a P-doped skeleton (Ru–Mo/PC) was successfully developed via a simple template-assisted pyrolysis method. Spherical aberration correction electron microscopy and X-ray absorption fine structure measurements revealed that the dual-active sites consisted of Ru–C5 single atoms and ultrasmall Ru–Mo nanoclusters (mean diameter of 0.94 nm). In particular, the as-constructed RuMo1.5/PC catalyst exhibited a high activity towards the HER, requiring an overpotential of only 17.9 mV at 10 mA/cm2, which outperformed a commercial Pt/C catalyst in alkaline media. Electrochemical performance results also indicated that introducing moderate Mo species played a crucial role in further boosting the HER activity compared to Ru/PC. The present work provides a step forward in designing efficient and stable catalysts with high-density, atomically dispersed active sites for hydrogen production.

A robust peroxymonosulfate activator for tetracycline degradation: Mitigating deactivation via stitching N-doped carbon nanotubes with encapsulated Co nanoparticles in bubble-like architectures

Peroxymonosulfate (PMS)-based advanced oxidation techniques provide feasible solutions to mitigate antibiotic contaminants, whereas conventional Co-based materials suffer from deactivation because of structural instability, serious metal leaching and inorganic/organic species poisoning. Herein, we propose a concept by constructing bubble-like architectures stitched by N-doped carbon nanotubes with encapsulated small Co nanoparticles (Co@NCNTs) to boost the deactivation resistance for tetracycline hydrochloride (TCH) degradation via PMS activation. This concept is performed through a NCNTs encapsulating and self-assembly strategy via a simple one-step pyrolysis using cobalt nitrate as metal source and imidazole as carbon/nitrogen sources and foaming agent. The optimal Co@NCNTs-600 exhibits a good catalytic activity with a removal efficiency of 93.1 % and a rate constant of 0.123 min−1 at 25 °C for TCH degradation via PMS activation. The catalyst can be easily isolated by an external magnet and reused for five times without obvious activity loss, indicating its excellent recycling stability. Radical quenching and electron paramagnetic resonance tests unveil the dominant non-radical pathway for TCH degradation with the Co@NCNTs-600/PMS system. The possible degradation pathways for TCH with the system are proposed. This study offers a feasible way to fabricate PMS activator for TCH removal with exceptional stability.

Lithiophilic onion-like carbon spheres as lithium metal uniform deposition host

Lithium metal is considered as a promising anode material for next-generation secondary batteries, owing to its high theoretical specific capacity (3860 mA h g−1). Nevertheless, the practical application of Li in lithium metal batteries (LMBs) is hampered by inhomogeneous Li deposition and irreversible “dead Li”, which lead to low coulombic efficiency (CE) and safe hazards. Designing unique lithiophilic structure is an efficient strategy to control Li uniformly plating /stripping. Here, we report the silver (Ag) nanoparticles coated with nitrogen-doped onion-like carbon microspheres (Ag@NCS) as a host to reduce the nucleation overpotential of Li for dendrite-free LBMs. The Ag@NCS were prepared by a simple one-step injection pyrolysis. The lithiophilic Ag is demonstrated to be priority selective deposition of Li in the carbon cage. Meanwhile, the onion-like structure benefits to uniform lithium nucleation and dendrite-free lithium during cycling. Impressively, we successfully captured lithium metal on different hosts at atomic scale, further proving that Ag@NCS can effectively and uniformly deposit Li. Besides, Ag@NCS show a superiorly electrochemical performance with a low nucleation overpotential (∼1 mV), high CE and stable cycling performance (over 400 cycles at 0.5 mA cm−2) compared to the Ag-free onion-like carbon in LMBs. Even under harsh conditions (1 mA cm−2, 4 mA h cm−2), Ag@NCS still present superior cycling stability for more than 150 cycles. Furthermore, a full cell composed of LiFePO4 cathode exhibits significantly improved voltage hysteresis with low voltage polarization. This work provides a new choice and route for the design and preparation of lithiophilic host materials.

Enhancing Potassium Storage Performance in VO2/V2O3@C Nanosheets by Synergistic Effect of Oxygen Vacancy and C‐O‐V Bond

AbstractThe potassium‐ion battery (PIB) is regarded as a promising energy storage system to replace lithium‐ion battery, while the sluggish kinetics and large K+ size result in inferior rate performance and poor cycle stability, impeding its extensive development. Here, a carbon coated VO2/V2O3 nanoparticles (VO2/V2O3@C) was prepared by simple reflux and pyrolysis process with polyaniline as the carbon source. The C−O−V bond and the oxygen vacancy within VO2/V2O3@C can not only accelerate the charge transfer between carbon and VO2/V2O3 nanoparticles, but also increase the active sites. Therefore, VO2/V2O3@C as an anode for PIB exhibits an excellent rate (78 mAh g−1 at 0.5 A g−1) and long‐cycling performance (147.9 mAh g−1 at 50 mA g−1 after 1000 cycles), and the full cell PIB shows high power density and energy density as well. This work provides a pathway to design other high‐performance anodes for PIBs.

Biowaste assisted preparation of self-nitrogen-doped nanoflakes carbon framework for highly efficient solid-state supercapacitor application

Porous carbon materials synthesized from renewable and biowaste resources are receiving a lot of interest due to their various applications, economic benefit, and proper waste management. Recently, a variety of biological precursors have been utilized to create self-heteroatom-doped carbon materials. Mangifera indica is known as one of the world's most significant tropical fresh fruits in total global production. Peels are a by-product and account for around 20 % of the total fruit weight whose removal has become a major issue. In this study, the self-heteroatom-doped porous carbon (H-PC) skeleton has been synthesized using simple KOH activation and pyrolysis process. Different characterizations are applied to evaluate the effects of temperatures and stoichiometric amounts of KOH on the morphology, pore structure, and content of heteroatom in carbon skeleton. Moreover, it shows a maximum specific capacitance (Csp) of 402 F g−1 with 1 A g−1 in acidic electrolytes and also it works in neutral electrolytes. The fabricated solid-state symmetric supercapacitor (SS-SC) device demonstrates excellent durability up to 10,000 cycles with the highest energy density (47 Wh kg−1) and a power density (14.3 kW kg−1) even in acidic electrolytes. This study shows new relationships between environmental improvement by waste management, biowaste conversion, and proper use of renewable energy.

Large‐Scale Synthesis of FeNi Nanoalloys‐Layered Porous N‐Doped Carbon Nanosheets for Efficient Electrocatalytic Water Splitting

AbstractDeveloping non‐noble metal catalysts with high efficiency and stability is critical for the industrial application of electrocatalytic water splitting. Herein, FeNi nanoalloys‐layered porous N‐doped carbon nanosheets (FeNi‐NCS) were large‐scale synthesized by simple formamide pyrolysis method. The framework of FeNi‐NCS was a micro‐flowerlike structure composed of mesoporous N‐doped carbon nanosheets as petals, on which FeNi nanoalloy particles were uniformly dispersed. Benefiting from the unique N doping electronic modification, hierarchically porous structure, and the synergetic effect between Fe and Ni, the FeNi‐NCS exhibited high intrinsic activity and robust structure which can improve catalytic performance significantly. By tuning the pyrolysis temperature and the molar ratio of Fe and Ni, the Fe1Ni1‐NCS‐900 displayed optimal activity and stability for electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) and required 261 and 310 mV overpotential to achieve 10 mA cm−2 respectively. This work presented a simple and effective way to fabricate high‐performance and stable non‐noble metal electrocatalysts for water splitting.

Mixed Metal Phthalocyanine-Modified Carbon Nanotubes for Bifunctional Oxygen Reduction and Evolution Reaction

In this ever-expanding world, researchers are focused on changing how we consume energy. Progress has been made over time, but the devices such as low-temperature polymer electrolyte fuel cells and metal-air batteries that can replace the conventional fossil fuel engines still use noble metal catalysts,1 which hinders the mass production and long-term usage of the devices. Transition metal macrocyclic (MN4-type) catalysts are good alternatives for the noble metal catalysts due to their low-price and promising electrocatalytic activity.2 Thus, the aim of this study was to develop the bifunctional ORR/OER electrocatalysts using mixed transition metal phthalocyanine-modified multi-walled carbon nanotubes (MWCNT) by simple pyrolysis method.3 Among the prepared bifunctional catalysts, FeCoN-MWCNT showed the superior electrocatalytic ORR activity in alkaline media with half-wave potential of 0.86 V vs RHE and FeNiN-MWCNT catalyst exhibited the exceptional OER activity with E j=10 mA cm–2 of 1.58 V (see Fig. 1a, b). Physical characterization of the prepared catalysts was investigated with (scanning) electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. Further, catalysts were tested in anion-exchange membrane fuel cells (AEMFCs) as cathode material and very good peak power density of 692 mW cm–2 was obtained for FeCoN-MWCNT (see Fig. 1c). FeNiN-MWCNT was tested in anion-exchange membrane electrolyzer (AEMEL) and showed comparable results with state-of-the-art RuO2 catalysts (Fig. 1d). Altogether, this study unveils the insight into potential ways of preparing the bifunctional ORR/OER electrocatalysts with transition metal macrocyclic-based compounds. References S. Hussain, H. Erikson, N. Kongi, A. Sarapuu, J. Solla-Gullón, G. Maia, A. M. Kannan, N. Alonso-Vante, K. Tammeveski, Int. J. Hydrogen Energy, 45, 31775-31797 (2020).A. Sarapuu, E. Kibena-Põldsepp, M. Borghei, K. Tammeveski, J. Mater. Chem. A, 6, 776–804 (2018).Y. Kumar, E. Kibena-Põldsepp, J. Kozlova, M. Rähn, A. Treshchalov A. Kikas, V. Kisand, J. Aruväli, A. Tamm, J. C. Douglin, S. J. Folkman, I. Gelmetti, F. A. Garcés-Pineda, J. R. Galán-Mascarós, D. R. Dekel, K. Tammeveski, ACS Appl. Mater. Interfaces, 13, 41507–41516 (2021). Figure 1

A novel hybridized needle-like Co3O4/N-CNO composite for superior energy storage asymmetric supercapacitors

The controlled growth of needle-like Co3O4 and composite formation with highly graphitic carbons such as N-CNOs is critically essential for obtaining high-performance energy storage supercapacitors. In this study, the needle-like Co3O4 and graphitic N-CNOs are synthesized by the simple solvothermal and pyrolysis methods, respectively. The Co3O4/N-CNO composite enhances the fast charge transfer by reducing ion diffusion. The Co3O4/N-CNO composite demonstrated an improved specific capacitance (3066 F g−1) than the needle-like structure of Co3O4 (2068 F g−1). The Co3O4/N-CNO composite exhibited very good rate capability and high capacitance retention of 82% at a high current density of 8 A g−1 meanwhile the Co3O4/N-CNO//AC ASC device shows high power and energy densities with capacitance retention of 78% and Coulombic efficiency of 100% over 2000 cycles. This attractive electrochemical performance of Co3O4/N-CNO composite makes it a favorable device for practical applications of supercapacitors.