Low-cost Precursor Research Articles

Activated carbons prepared via reflux-microwave-assisted activation approach with high adsorption capability for methylene blue

The paper reported a facile method to prepare activated carbons (ACs) with high methylene blue (MB) adsorption capabilities via reflux-microwave-assisted activation approach. The low-cost agricultural waste corncob precursor was first refluxed in the aqueous solution of activating agents (i.e., ZnCl2 or KOH) for pretreatment, followed by microwave-assisted activation. The reflux process significantly shortens the pretreatment time to 4 h, compared to usually 24 h soaking in the traditional practice; and meanwhile greatly facilitates the diffusion of the activating agents into the precursor; whereas the microwave-assisted activation endows the ACs with hierarchical pore structures and a high specific area (e.g, 1405 m2/g for KOH pretreated AC). The ACs are also featured with rich oxygen-containing functional groups such as hydroxyl groups on the surface, and exhibit high adsorption capacity using MB as a model adsorbate because of the electrostatic interactions. Under the optimum condition (the impregnation ratio of KOH to the corncob of 2:1 (wt. %), microwave power of 600 W, and microwave time of 7 min), the prepared KAC demonstrates an adsorption capacity of as high as 636.94 mg/g. Moreover, the ACs can be readily regenerated by alkaline solution and still show satisfying adsorption performance after three times of regeneration. These findings indicate the feasibility of preparing high adsorption performance ACs by reflux-microwave-assisted activation approach.

In Situ Doping-Enabled Metal and Nonmetal Codoping in Graphene Quantum Dots: Synthesis and Application for Contaminant Sensing

Fluorescent graphene quantum dots (GQDs) prepared from low-cost and sustainable precursors are highly desirable for various applications, including luminescence-based sensing, optoelectronics, and ...

Enhanced stem cell retention and antioxidative protection with injectable, ROS-degradable PEG hydrogels

Poly(ethylene glycol) (PEG) hydrogels crosslinked with enzyme-cleavable peptides are promising biodegradable vehicles for therapeutic cell delivery. However, peptide synthesis at the level required for bulk biomaterial manufacturing is costly, and fabrication of hydrogels from scalable, low-cost synthetic precursors while supporting cell-specific degradation remains a challenge. Reactive oxygen species (ROS) are cell-generated signaling molecules that can also be used as a trigger to mediate specific in vivo degradation of biomaterials. Here, PEG-based hydrogels crosslinked with ROS-degradable poly(thioketal) (PTK) polymers were successfully synthesized via thiol-maleimide chemistry and employed as a cell-degradable, antioxidative stem cell delivery platform. PTK hydrogels were mechanically robust and underwent ROS-mediated, dose-dependent degradation in vitro, while promoting robust cellular infiltration, tissue regeneration, and bioresorption in vivo. Moreover, these ROS-sensitive materials successfully encapsulated mesenchymal stem cells (MSCs) and maintained over 40% more viable cells than gold-standard hydrogels crosslinked with enzymatically-degradable peptides. The higher cellular survival in PTK-based gels was associated with the antioxidative function of the ROS-sensitive crosslinker, which scavenged free radicals and protected encapsulated MSCs from cytotoxic doses of ROS. Improved MSC viability was also observed in vivo as MSCs delivered within injectable PTK hydrogels maintained significantly more viability over 11 days compared against cells delivered within gels crosslinked with either a PEG-only control polymer or a gold-standard enzymatically-degradable peptide. Together, this study establishes a new paradigm for scalable creation and application of cell-degradable hydrogels, particularly for cell delivery applications.

Enhancing removal of Cu(II) from aqueous solution by walnut shell-based activated carbon with pyrolusite modification

ABSTRACT Pyrolusite modified carbon was prepared from walnut shell for enhancing removal of Cu(II) from aqueous solution. 1% pyrolusite addition was proved to be efficient and economic on adsorption capacity improvement of the produced carbon. Cu(II) removal rate on the modified walnut shell-based carbon was ca. 20% higher than the unmodified one, while the adsorption capacity for the modified carbon was high up to 34.4 mg/g. Within weakly acidic pH range (pH = 5 ~ 6), it was suitable for Cu(II) adsorption with larger than 97% removal rate on the produced carbon. SEM and BET analysis showed that pyrolusite played an important role on pore formation of the produced carbon. The specific surface area, mesopore and micropore volume of the modified carbon were 27.2%, 39.5%, 17.5%, respectively, higher than those of the unmodified one. After modification, oxygen-containing functional groups, especially phenol and carbonyl groups, were remarkably increased on the produced carbon, which were helpful for Cu(II)’s adsorption. FTIR showed that a large amount of organic carbon was decomposed into inorganic carbon skeleton during the carbonisation process, thus forming a large number of pores, and was conducive to adsorbing copper ions. This work is expected to be helpful for an effective agricultural residue management and innovative modification of walnut shell-based adsorbent as low-cost precursors for heavy metal treatment.

Eco-friendly and scalable synthesis of micro-/mesoporous carbon sub-microspheres as competitive electrodes for supercapacitors and sodium-ion batteries

Cost-efficiency utilization of carbon sub-microspheres is greatly significant for their versatile energy-related applications. However, eco-friendly synthesis and moderate activation protocols for enhancing their electrochemical performances are still challenging. Herein, we explore a facile two-step methodology, i.e., hydrothermal carbonization and subsequent mild activation, for bottom-up fabrication of KHCO3 activated micro-/mesoporous carbon microspheres (MCMS-K) as competitive electrodes towards electrochemical capacitors (ECs) and sodium-ion batteries (SIBs) by using the soluble starch as a low-cost precursor. Benefitting from its high specific surface area (~1972.8 m2 g−1), abundant micropores (~88.8%), and high graphitization degree, the MCMS-K electrode obtains a specific capacitance of ~369.8 F g−1 (~266.3 F cm−3) at 1 A g−1 in 1 M H2SO4, higher than that in 6 M KOH, thanks to the surface oxygen functional groups involved pseudocapacitance. More remarkably, the MCMS-K based organic symmetrical ECs deliver a high-rate energy density of 34.4 Wh kg−1 at 12.5 kW kg−1, and ultra-long cycling stability. Besides, the MCMS-K anode renders a high-rate capacity of ~78.6 F g−1 at 5.0 A g−1via Na+ surface adsorption and intercalation accompanying with excellent cycling behaviors for SIBs. It strongly highlights the promising applications of our MCMS-K product in ECs and SIBs.

Oil-miscible, halogen-free, and surface-active lauryl sulphate-derived ionic liquids for enhancement of tribological properties

Halogen-free ionic liquids, comprising low-cost surface-active precursors, having good miscibility with synthetic and mineral lube base oils, and enhance the lubrication properties by reducing the friction and wear, are gaining increasing attention for tribological applications. The present work addresses lauryl sulphate-derived tetraalkylammonium/phosphonium ionic liquids. Total four ionic liquids comprising tetrabutyl- and tetraoctyl-based quaternary structure are synthesized and then demonstrated them as additives to mineral and synthetic lube base oil for enhancement of lubrication properties. The tetraalkylphosphonium cation-based ionic liquids exhibited higher thermal stability, whereas the tetraalkylammonium cations-based analogue showed superior viscosity. These ionic liquids as an additive to PEG 200 and SN 150 lube base oils increased the viscosity index. The 1.5 w/v% of lauryl sulphate anion-based ionic liquids as an optimized dose to PEG 200 oil significantly improved the tribological properties by decreasing the friction (28%) and wear volume (91%). The enhancement of tribological properties by these ionic liquids is attributed to the formation of tribochemical thin film on the contact interfaces as deduced from their spectroscopic measurements. Furthermore, the tribo results revealed that the alkyl chains in cationic moieties and the viscosity of ionic liquids govern the frictional characteristics.

In-situ growth of graphene on carbon nanofiber from lignin

Design and synthesis of heterostructured carbon nanofibers is significant for applications in the field of optoelectronics, conductors and catalytic devices. Although lignin has been widely used as building blocks for fabricating nanofibers, it is still very challenging to synthesize conducting heterostructured carbon nanofibers without using additional catalysts. Herein, we first in-situ grew graphene grafted carbon nanofibers (G/CNFs) using calcium lignin sulfonate as starting materials without addition of catalysts. Through the electrospinning, pyrolysis and washing procedure, the as-spun nanofibers are converted into the flexible G/CNFs films. The in-situ formed CaS nanoparticles serve as catalysts for the growth of graphene on the surface of the CNFs, when the carbonization temperature is over 1100 °C. The as-prepared G/CNFs films exhibit superior electronic conductivity of 2377.9 S m−1, which is comparable to the values reported in the literature. As a proof-of-concept, the as-fabricated lithium-sulfur battery exhibits a high discharge of 808.7 mAh·g−1 after 600 cycles at 0.2 C by using the G/CNFs membrane as stand-alone and flexible sulfur cathode scaffolds. This work represents a promising new approach for designing heterostructured graphene/CNFs using low-cost lignin precursors, and provides significant insights for the sustainable development of CNFs in numerous applications.

Lignin derived hierarchical porous carbon with extremely suppressed polyselenide shuttling for high-capacity and long-cycle-life lithium–selenium batteries

A low-cost scalable strategy is developed to fabricate lignin derived hierarchical porous carbon as a high-loading Se host. When combined with carbonate-based electrolyte, the high-capacity and long-term cycling Li–Se batteries were obtained. Lithium–selenium (Li–Se) batteries have attracted considerable attentions for next-generation energy storage systems owing to high volumetric capacity of 3265 mAh cm −3 and excellent electronic conductivity (~10 −5 S cm −1 ) of selenium. However, the shuttling effect and capacity fading prevent their wide applications. Herein we report a low-cost strategy for scalable fabrication of lignin derived hierarchical porous carbon (LHPC) as a new high-loading Se host for high-capacity and long-term cycling Li–Se batteries in carbonate electrolyte. The resulting LHPC exhibits three-dimensional (3D) hierarchically porous structure, high specific surface area of 1696 m 2 g −1 , and hetero-atom doping (O, S), which can effectively confine the Se particles into the micropores, and meanwhile, offer effective chemical binding sites for selenides from hetero-atoms (O, S). As a result, our Li–Se batteries based on Se@LHPC demonstrate high capacity of 450 mAh g −1 at 0.5 C after 500 cycles, with a low capacity fading rate of only 0.027%. The theoretical simulation confirmed the strong affinity of selenides on the O and S sites of LHPC effectively mitigating the Se losing. Therefore, our strategy of using lignin as the low-cost precursor of hierarchically porous carbon for high-loading Se host offers new opportunities for high-capacity and long-life Li–Se batteries.

A Na-rich fluorinated sulfate anti-perovskite with dual doping as solid electrolyte for Na metal solid state batteries

High-conductivity solid electrolytes are crucial components for the development of Na-based solid state batteries. However the electrolyte structure prototype and corresponding synthesis method are still lacking. The conventional oxide and sulfide electrolytes are precursor-expensive (e.g. Na2S) or energy-intensive in sintering synthesis (e.g. at 1000 ​°C). Here, we propose a novel anti-perovskite solid electrolyte of Na-rich fluorinated sulfate (Na3SO4F) benefiting from Mg and Cl co-doping by solid state reaction from low-cost precursors at moderate temperature (500 ​°C). The tailored dual doping enables an improvement of ionic conductivity by three orders of magnitude close to 10−4 ​S ​cm−1 at 60 ​°C. The creation of Na vacancies (by aliovalent Mg doping) and lattice expansion (by substituting F sites with larger-sized Cl ions) are responsible for the conductivity upgrade. A Na–Sn/Fe [Fe(CN)6]3 solid state battery based on Na2.98Mg0.01SO4F0.95Cl0.05 electrolyte can reversibly run with a first discharge capacity as high as 91.0 mAh g−1 and a reversible capacity preserved at 77.0 mAh g−1. This result paves a way to novel anti-perovskite family of fluorinated sulfates as potential alkali metal ion solid electrolytes beyond already reported A3OX (A ​= ​Li or Na, X ​= ​heavy halogen or hydrogenide anions) anti-perovskites.

Synthesis, Characterization and Mechanism Study of Green Aragonite Crystals from Waste Biomaterials as Calcium Supplement

In present work, environmentally benign green aragonite crystals were synthesized from waste chicken eggshells and bivalve seashells through a simple and low-cost wet carbonation method. This method involves a constant stirring of calcium oxide slurry and magnesium chloride suspension in aqueous solution with constraint carbon dioxide injection at 80 °C. The physicochemical properties of the synthesized aragonite were further compared with the aragonite synthesized from commercial calcium oxide. The morphological analysis, such as acicular shape and optimum aspect ratio (~21), were confirmed by scanning electron microscopy. The average crystal size (10–30 µm) and specific surface area (2–18 m2 g−1) were determined by particle size and Brunauer–Emmett–Teller analysis, respectively. Moreover, a schematic crystal growth mechanism was proposed to demonstrate the genesis and progression of aragonite crystal. Green aragonite can bridge the void for numerous applications and holds the potential for the commercial-scale synthesis with eggshells and bivalve seashells as low-cost precursors.

Binder less-integrated freestanding carbon film derived from pitch as light weight and high-power anode for sodium-ion battery

To realize the large scale application of sodium-ion batteries (SIBs), a stable, cost-effective anode is desired. Pitch is a potential low-cost precursor to synthesize soft carbon anode for SIBs. However, it exhibits poor Na-ion storage. Herein, we report the facile synthesis of pitch derived-binder less-metal free-freestanding anode for storing Na-ions by one-step pyrolysis process between the temperature range 700–1000 °C under nitrogen atmosphere. We replace conventional Cu-current collectors with non-graphitic carbon fiber (CFs) mats. The electrode architecture not only eliminates the metallic current collector, conductive diluents, and inactive organic binder but also provides an ideal porous network for sodium-ion and electrolyte diffusion into the bulk of the electrode. The freestanding electrode delivers a reversible capacity of 310 mAh g−1 in comparison to 180 mAh g−1 for the conventional electrode at the current density of 50 mA g−1. Good C rate performance and cycling stability over 500 cycles (at 1 A g−1) of this freestanding electrode indicate as a promising anode for SIBs. The evolution of plateau region capacity (<0.1 V) in free-standing electrodes leads to higher capacity value in comparison to a conventional electrode. To understand further, the cyclic voltammetry curves at various sweep rates are used and it is observed that the Na-ion storage behavior within the conventional electrode is mostly capacitive, whereas the behavior is diffusion dominant in case of the freestanding electrode. Finally, the freestanding electrodes are implemented as anodes and fluorophosphate based material as the cathode to realize its practical realization in sodium-ion full cell.

Scalable Synthesis and Kinetic Studies of Carbon Coated Sodium Titanate: A Promising Ultra-low Voltage Anode for Sodium Ion Battery

The ultra-low voltage anode, Na2Ti3O7 (NTO) of high specific capacity (177 mAh/g) suffers from low intrinsic electronic conductivity, leading to poor electrochemical performance. Herein, we report the synthesis of carbon-coated Na2Ti3O7 (NTO/C) from indigenously prepared TiO2; where a low-cost organic precursor, resorcinol is used as a carbon source for the first time. Resorcinol derived carbon is beneficial in two ways: (1) increase in electronic conductivity; and (2) promote sodium ion intercalation being electrochemically active. The structural and morphological characterizations are conducted by X-ray diffraction, Fourier transform infra-red spectroscopy, scanning electron microscopy and transmission electron microscopy techniques, which confirm the formation of phase pure NTO/C with cuboid-shaped morphology. The carbon coating along with cuboid type morphology together show improved electrochemical performance due to the increase in electronic conductivity and sodium ion diffusivity. The NTO/C shows higher reversible charge capacity of 213 (± 5) mAh/g with 48% capacity retention against 178 (± 5) mAh/g with 24% capacity retention for pristine NTO after 40 cycles. Excellent rate capability is seen for NTO/C; where it shows a stable capacity of 70 (± 5) mAh/g at 2.0 C-rate. The novelty of this present work involves large scale synthesis of carbon-coated Na2Ti3O7 from indigenously prepared TiO2 and low-cost resorcinol as a source of carbon with improved electrochemical performance, which can be used as promising intercalation based anode material for sodium-ion batteries.

Kinetics of CO methanation using a Fe-bearing catalyst from a blast furnace sludge

Hydrogenation of CO for methane production was studied using blast furnace sludge (BFS), a Fe-rich residue, as a catalyst. Previously, the raw BFS was subjected to successive leaching stages to reduce some inhibitor compounds. The catalytic runs were carried out in a laboratory scale differential reactor, at 300–350 °C, 1 atm, and variable partial pressures of H2 (10–50 kPa) and CO (0.25–3.0 kPa). Before the reaction, the catalyst was reduced in H2 at 500 °C for 2 h. Product gases were analyzed by gas chromatography. The BFS, reduced (BFS-R), leached (BFS-L) and leached and reduced (BFS-L-R) catalysts were characterized by atomic absorption spectroscopy (AAS), in situ X-ray diffraction (XRD), N2-physisorption at 77 K and thermogravimetric-mass spectrometry analysis (TG-MS). Some selected samples were also analyzed by X-ray photoelectron spectroscopy (XPS). Iron content in the leached sample was 51.7 wt%, present mostly as hematite (Fe2O3) and magnetite (Fe3O4). Carbon was also detected in the BFS-L-R, although its influence on CH4 formation was found to be negligible. When BFS-L-R was used as a catalyst, at 320 °C and H2/CO = 20:1, rate of methane production and selectivity achieved 2.63 μmolCH4/gcat/min and 49.5%, respectively. Experimental results demonstrated that, under the studied conditions, CO hydrogenation towards CH4 proceeds through an H-assisted reaction path. Langmuir-Hinshelwood rate laws for both CH4 and the undesired CO2 production were derived, and parameters were adjusted from the obtained data. The activation energy for methane formation was 93.2 kJ/mol.To evaluate the catalyst resistance to poisoning, a BFS-L sample was treated with SO2 prior to the reaction tests. A first-order deactivation model was consistent with the data. The results of this work demonstrate the feasibility of BFS as a low-cost precursor of a methanation catalyst. Although this is a realistic alternative, further research, both experimental and modeling are still required to optimize operating conditions and to explore different reactor configurations.

3D-interconnected framework binary composite based on polypyrrole/textile polyacrylonitrile-derived activated carbon fiber felt as supercapacitor electrode

Supercapacitors have been studied due to their promising as powerful storage devices. The development of highly efficient electrodes is one way to manufacture supercapacitors with high energy and power efficiencies. Binary composites based on activated carbon fiber felt (ACFF) and polypyrrole (PPy) have been investigated to increase capacitance performance. ACF, when applied as a bulk electrode has limited electric characteristics while the PPy suffers from limited stability during cycling that reduces the initial performance. Based on the synergism effect, this work proposes the production of a binary composite based on ACFF produced from a low-cost precursor textile polyacrylonitrile (textile PAN) and the facile synthesis of PPy from the chemical route of polymerization. The binary composite formed by a 3D network with the interconnection of a more conductive form of PPy coated on ACFF was obtained. The resulting architecture was determinant to significantly increase the energy storage capacities when compared to the bulk ACFF electrode. From the galvanostatic charge and discharge curves, cyclic voltammetry and electrochemical impedance, the obtained composite had a specific capacitance about 302 F g−1 associated with low resistance and to a good density of energy and power.

Non-Pt Nanofibrous Catalysts for an ORR PEM Fuel Cell Cathode

Electrospun nanofibrous catalysts made of non-Platinum group metal (non-PGM), low cost precursors are studied for the ORR to be applied in a PEM fuel cell cathode. Optimizing the structure of proton exchange membrane (PEM) fuel cell cathodes is essential to reduce the high cathode loadings (1 to 6 mg of catalyst per cm2), used for non-PGM catalysts to compensate for the lower activity against standard Pt catalysts. Electrospinning is used to shape the catalytic precursors in a network of nanofibers to study the effect of the electrospun architecture with respect to fuel cell performance.

Electrospun Li1.3Al0.3Ti1.7(PO4)3 Nanofibers to Develop Solid-State Electrolytes for Lithium Metal Batteries

During the last decades lithium-ion battery (LIB) has progressively become the benchmark for developing novel energy storage systems for portable and automotive applications. Although the energy density of commercial LIBs has increased significantly over time, it is now reaching a physicochemical limit (~800 Wh L-1), which arises from current materials technology [1]. Hence, a new paradigm is needed to develop next-generation high-energy batteries. A promising candidate is the all-solid-state lithium battery, which features a solid ion-conductive material acting as both separator and electrolyte and usually referred to as solid-state electrolyte (SSE). When compared to flammable organic-based liquid electrolytes, widely used in commercial LIBs, SSEs are characterized by better electrochemical and thermal stabilities as well as by a higher mechanical strength, all of which are beneficial for the safety of the final device. They also enable the use of lithium metal as anode, which potentially increases the volumetric energy density of the cell by up to 70% [1]. SSEs are usually made of polymeric, ceramic or composite materials and, regardless of the composition, they are characterized by some key issues that undermine the performance of the final device. Specifically, the low ionic conductivity at room temperature and the poor interfacial compatibility with the electrodes are the main challenges the scientific community is addressing. Recently, the use of 1-dimensional structures as nanofiller has been reported as an effective strategy to improve ionic conductivity and mechanical properties of composite polymer electrolytes (CPEs) [2–4]. Inorganic nanowires and nanofibers resulted to be also advantageous for increasing the density and therefore the ionic conductivity of ceramic electrolytes [5,6].Herein, we propose the use of ceramic NASICON-like Li1.3Al0.3Ti1.7(PO4)3 (LATP) nanofibers to develop SSEs for lithium batteries. LATP is one of the most promising ceramic material for designing an SSE because it has the highest ionic conductivity in the Li-NASICON family (7 · 10-4 S cm-1 at 25 °C), it is chemically and thermally stable in atmosphere conditions, and it can be synthesized by using low cost and easily-processable precursors [7]. The synthesis of LATP nanofibers was performed by incorporating an electrospinning step into a conventional sol-gel process [8]. Specifically, a solution containing the precursor materials and a polymer carrier was electrospun to produce a nanofibrous precursor membrane. The achieved membrane was then calcined to synthesize ceramic LATP nanofibers. Purity and morphology of the synthesized material have been investigated by X-ray diffraction and electron microscopy techniques. Finally, LATP nanofibers have been used as ceramic filler to produce a poly(ethylene oxide)-based CPE. Its electrochemical performance are here discussed and compared to those of the equivalent nanoparticle-filled CPE and the plain polymer electrolyte. Preliminary data on a dense ceramic electrolyte achieved by pressing and then calcining the precursor membrane are here reported too.[1] J. Janek, W.G. Zeier, Nat. Energy 1 (2016) 16141 [2] T. Yang, J. Zheng, Q. Cheng, Y.-Y. Hu, C.K. Chan, ACS Appl. Mater. Interfaces 9 (2017) 21773–21780. [3] W. Liu, S.W. Lee, D. Lin, F. Shi, S. Wang, A.D. Sendek, Y. Cui, Nat. Energy 2 (2017) 17035. [4] Z. Wan, D. Lei, W. Yang, C. Liu, K. Shi, X. Hao, L. Shen, W. Lv, B. Li, Q.-H. Yang, F. Kang, Y.-B. He, Adv. Funct. Mater. 29 (2019) 1805301. [5] T. Yang, Z.D. Gordon, Y. Li, C.K. Chan, J. Phys. Chem. C 119 (2015) 14947–14953. [6] T. Yang, Y. Li, C.K. Chan, J. Power Sources 287 (2015) 164–169. [7] H. Aono, E. Sugimoto, Y. Sadaoka, N. Imanaka G. Adachi, J. Electrochem. Soc. 137 (1990) 1023–1027. [8] A. La Monaca, A. Paolella, A. Guerfi, F. Rosei, K. Zaghib, Electrochem. Commun. 104 (2019) 106483.

Pitch Derived Carbon As Light Weight and High-Power Sodium-Ion Battery Anode

Li-ion batteries (LIBs) are fulfilling the current need of humankind, the high abundance, and accessibility of sodium, making Na-ion batteries (NIBs) a promising LIBs supplement in the large-scale energy storage application.1, 2 However, the commercial success of NIBs demands an appropriate cathode and anode material. From the cathode material viewpoint, the literature reports suggest that O3/P2 type layered oxide can deliver a reasonable capacity with good cycling stability2. Graphite, the state-of-art anode material in LIBs is electrochemically inactive to intercalate Na-ions. Na-ion intercalation into graphite lattice is a thermodynamic driven process, where most Na-rich graphite intercalation compounds (GIC) prepared to date is NaC64 with a1 capacity of only 35 mAh g-1.3 However, Li-ion and K-ion form the stage one Li-GIC and K-GIC having the formula LiC6 and KC8, which makes them electronically active in Li- and K-ion battery, respectively. 4,5 To realize the large scale application of sodium-ion batteries, a stable, cost-effective anode is desired. Carbon-based anode materials are always attractive because of ease of fabrication, cost, and feasibility towards practical application. The pioneering work of Dahn and Stevens on hard carbon anode, reports the sodiation capacity of 300 mAh g-1 at room temperature.6 Later on, the hard carbon derived from different precursors such as a polymer, biomass, resin, etc., and applied as anode for Na-ion battery.7 However, hard carbon materials mostly suffer from poor carbon synthesis yield and high cost.8 Therefore, exploring cost-effective precursors and process is very crucial to realize the large scale application of NIB.Pitch is a potential low-cost precursor to synthesize soft carbon anode for NIBs. However, it does not exhibit decent Na-ion storage. Herein, we report the facile synthesis of pitch derived-binder less-metal free-freestanding anode for storing Na-ions by one-step pyrolysis process between the temperature range 700-1000 oC under nitrogen atmosphere. We replace conventional Cu-current collectors with carbon fiber (CFs). The electrode architecture not only eliminates the metallic current collector, conductive diluents and inactive organic binder but also provides an ideal porous network for sodium-ion and electrolyte diffusion into the bulk of the electrode. The freestanding electrode delivers a reversible capacity of 310 mAh g-1 in compare to 180 mAh g-1 for conventional electrode at the current density of 50 mA g-1. The cycling stability over 500 cycles (at 1 A g-1) and C-rate performance of freestanding anode dictate it as a promising anode for NIBs. The overall charge storage properties of conventional and freestanding-film are quantified into pseudocapacitive and diffusion-control Na+ intercalation. Further, the freestanding film is implemented as anode in order to realize its practical application in sodium-ion full cell. It is believed that the study may open up a new approach to modify the pitch based soft-carbon precursors as anode for low-cost, high-energy NIBs. Acknowledgments SG acknowledges MHRD, VKK acknowledges UGC-NET, Govt. of India, and SKM acknowledges Research Center Imarat (DRDO), Hyderabad under grant no. RCI/CAAT/8151/CARS-358 for financial support.

Graphitic Carbon Nitride: An Excellent Base for Composite Electrodes in Electrochemical Energy Conversion and Storage

Growing environmental concerns linked with global energy demands have increased the need for sustainable, reliable and portable energy supply that can be delivered from energy conversion to energy storage. Although some emerging electrocatalysts can potentially compete with commercial electrocatalysts in terms of cost per unit kWh when using low-cost precursors to create them, research efforts are still mainly focusing on performance rather than cost. It is expected that flexible energy storage devices with multifunctionalities would spearhead the power management of future energy devices, which requires engineering solutions of volume and weight reduction. Nanocomposites that offer simultaneous energy conversion and storage capabilities with mechanical load bearing are promising candidates to provide these desired functionalities in electrochemical devices. Utilizing hierarchical porous polymers with combined properties of light weight, flexibility and absorption capacity offers numerous possibilities for the development and utilization of nanocomposites in applications ranging from electronics, aerospace, military to transportation where rapid or stored burst of energy is required for peak power, backup power and load levelling to achieve improved efficiency and reliability.In this work, iron oxide nanoparticles encapsulated in graphitic carbon nitride shells (Fex-NC) were grown on interconnected, macroscopic carbon scaffold after dip coating followed by carbonization to attain multifunctional nanocomposites. The resulting composites based on the graphitic carbon nitride base possess combined properties of superb structural flexibility, high strength to weight ratio and mechanical stability. The Fex-NC nanocomposites were tested for energy conversion and storage, to take advantage of their porous graphitic carbon nitride features which would be beneficial for optimal ion transport to iron oxide nanoparticles. We have found that the resulting graphitic carbon nitride shells prevented direct contact between iron oxide nanoparticles and acidic electrolyte (H2SO4), so that improved efficiency, stability and corrosion resistance were achieved. They also exhibit excellent electrochemical performances with overpotentials of 191 mV to reach current density of 10 mA/cm2 for hydrogen evolution reaction. In addition to demonstrating excellent specific capacitance, these nanocomposites also possess good stability after 8 hours of testing. The results demonstrate that the physicochemical properties of multifunctional 3D foams developed from simultaneous carbonization and dip coating of polymeric templates can be used as an excellent base to host a variety of nanoparticles to create composite electrocatalysts and be further exploited for future energy and environmental technologies.

Low-cost synthesis of AuNPs through ultrasonic spray pyrolysis

The present research informs about the synthesis of gold nanoparticles (AuNPs) through Ultrasonic Spray Pyrolysis (USP), which were collected in ethanol with 0.1% Polyvinylpyrrolidone (PVP). Initially, the research focused on two precursors, where the first represented a homemade H-HAuCl4, completed in our own laboratory through the chlorine gas method by using HCl and KMnO4, and the second was the commercial C-HAuCl4, prepared by using Gold (III) chloride tetrahydrate powder and deionised water. The goal was to find any potential precursor differences and their influences on the later use for AuNPs synthesis through USP using almost the same parameters. In the first step of research it was determined that the H-HAuCl4 precursor was similar to C-HAuCl4 in chemical composition, surface tension and pH value. This finding represented the starting point for being able to use H-HAuCl4 in the USP for AuNPs‘ synthesis. In the second step, AuNPs were synthesised from both types of precursors. Afterwards, characterisation of some functional properties by FTIR and UV–vis techniques was done directly for H- and C-AuNPs in the collecting media. For SEM/EDX and TEM microscopy both types of H- and C-AuNPs were dried, and observation revealed that the morphology, shape and size distribution of dried AuNPs were very similar. Based on the performed laboratory research, it could be concluded that prepared H-AuNPs could represent a new and low-cost effective solution for future USP transfer onto the industrial level, not only in in the process itself, but also in the field of Low-cost Precursor Preparation.

A Sustainable Route to Synthesize Graphene Oxide/Ordered Mesoporous Carbon as Effect Nanocomposite Adsorbent.

Rice husk is an agricultural waste that provides an alternative renewable source of bioenergy. Burning rice husk can produce rice husk ash. The rice husk ash is a potential resource of low-cost precursor for synthesizing high value-added materials. This paper reports the synthesis of SBA-15 mesoporous silica from recycled rice husk ash waste. Next, graphene oxide/ordered mesoporous carbon (GO/CMK-3) nanocomposite was synthesized using the SBA-15 template. The composite was investigated by X-ray diffractometer, field-emission scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectrometer, Raman spectrometer and surface area analyzer. Experimental results confirmed that GO/CMK-3 composite possessed high surface area (936 m²/g), large pore volume (1.077 cm³/g), and uniform pore size (4.35 nm). The mesopore structure was not destroyed by the introduction of GO. Methylene blue was employed as an adsorbate to evaluate the adsorption capacity of GO/CMK-3 composite. The GO/CMK-3 revealed much higher adsorption capacity levels than did pure CMK-3 and SBA-15. The adsorption capacity decreased with increasing solution temperature, and increasing initial concentration of dye. The thermodynamic observation indicated that the total adsorption process was spontaneous and exothermic. The conversion of rice husk ash waste into GO/CMK-3 composites can be regarded as an economically beneficial by-product for reducing environmental pollution.