One-pot Spray Pyrolysis Research Articles

One-pot spray pyrolysis method for nanostructured cobalt sulfide–C composite microspheres using recovered cobalt sulfuric acid solution and their excellent properties as anode materials for potassium-ion batteries

A pioneering synthesis approach for nanostructured cobalt sulfide-C composites from waste materials is proposed. By combining recycling processes with one-pot spray pyrolysis, a cost-effective and efficient synthesis method is achieved.

분무열분해 단일공정을 통한 리튬이온전지 음극소재용 MoO3 나노분말

MoO₃ nanopowders having an average size of 150 nm as anode materials for lithium ion batteries were synthesized by one-pot spray pyrolysis process. During the spray pyrolysis process, concentration difference in a droplet occurred due to the high flow rate of the carrier gas, which induced hollow intermediate powders. The intermediate hollow powders are composed of MoO_x and C, and subsequently they are decomposed into MoO₃ nanopowders without C under oxidation atmosphere. When MoO₃ nanopowders were used as anode materials, the cell showed reversible discharge capacity of 390 mA h g-¹ at a current density of 1.0 A g^-1 even after 1,000 cycles. The overwhelming cycle stability of the cell is attributed to the MoO₃ nanopowders with 150 nm that act as an effective anode material by shortening the diffusion length of Li ions to the electrode and increasing the contact surface with the electrolyte during cycles.

One-pot spray pyrolysis for core–shell structured Sn@SiOC anode nanocomposites that yield stable cycling in lithium-ion batteries

A novel strategy is reported for the synthesis of high-capacity anode materials with good cycling stability for use in lithium-ion batteries. A facile one-pot spray pyrolysis process is conducted using an ethanol solution of Sn acetate and diphenylsilanediol (DPSD). Phase separation between Sn and DPSD leads to the formation of core@shell-structured Sn@DPSD nanoparticles, and subsequent heat-treatment in an inert atmosphere carbonizes the DPSD to form Sn@SiOC nanoparticles (∼50 nm). When applied as an anode material in lithium-ion batteries (LIBs), the Sn core retains its high energy density, while the SiOC shell limits volume expansion of the core and protects it from pulverization and agglomeration. The Sn@SiOC nanoparticles exhibit a reversible capacity of 917 mA h g −1 at 0.1C and stable cycling performance for 200 cycles at 1C. The nanoparticle formation mechanism is investigated by optimizing the Sn acetate/DPSD ratio in the precursor solution, and the origin of the enhanced properties is investigated by comparing the results of Sn@SiOC nanoparticles with those of SiOC nanoparticles and Sn microspheres. SiOC shows considerable promise as a coating material for Sn nanoparticles, which may serve as a milestone in the synthesis of nanosized electrode materials with coatings that can prolong the cycle lives of rechargeable batteries.

Highly porous structured Sr-doped La2NiO4/NiO composite cathode with interconnected pores for lithium-oxygen batteries

• Highly porous OP-SLNO was prepared by one-pot spray pyrolysis. • OP-SLNO showed improved catalytic abilities for both OER and ORR. • OP-SLNO with interconnected pores was suitably applied to Li-O 2 batteries. • Interconnected pores provided space to accommodate abundant discharge products. One-pot spray pyrolysis process is a promising continuous process for mass production of nanostructured powder. The highly porous microspheres containing pores interconnected from the inner to the outer side of particle are prepared by one-pot spray pyrolysis process. In this study, Sr-doped layered perovskite oxide is selected as the first target material. A colloid comprising mono-sized spherical templates were used as a precursor to synthesize the porous Sr-doped La 2 NiO 4 /NiO composite powder. The fine and spherical templates construct a highly open and porous structure throughout the resulting particle’s inner bulk and surfaces. The fabricated powder shows improved catalytic abilities for both OER and ORR, based on the results of the RDE measurements. Owing to the open-pore structure, the overpotentials for both discharge and charge processes are lowered attributing to extremely improved cycle life of over 180 cycles when applied to Li-O 2 cell, while the filled-structured powder gives less than 50 cycles. Furthermore, the Li-O 2 cell reveals definitely improved discharge capacity of 13,130 mA h g −1 under 200 mA g −1 owing to the interconnected pore structure, when compared to discharge capacities of closed-pores-containing powder (9,547 mA h g −1 ) and filled-structured powder (7,541 mA h g −1 ).

Oxygen defective bimodal porous Ni-CeO2−x-MgO-Al2O3 catalyst with multi-void spherical structure for CO2 reforming of CH4

Ni-CeO2-MgO-Al2O3 catalysts with bimodal meso-macropores have been synthesized by one-pot spray pyrolysis using dextrin as a structuring agent for dry reforming of methane. The formation of macropores originating from phase segregation and the decomposition of dextrin positively affects both the physical and chemical features of the catalysts, and therefore, the bimodal porous catalysts outperform the dense catalysts in catalytic activity and stability. The volume and size of macropores in a bimodal porous catalyst are dependent on the concentration of dextrin. Based on diverse characterization results, this morphological change has been revealed to induce the distortion of the CeO2 lattice and embedding of Ni nanoparticles, resulting in the strong interaction between the metal and support/promoter and high oxygen storage capacity. The catalyst with balanced bimodal pore structures and optimized physicochemical parameters showed the best performance, considering both catalytic activity and stability with high sintering/coking resistance in the dry reforming of methane.

A facile strategy towards high capacity and stable Sn anodes for Li-ion battery: Dual-confinement via Sn@SnO2 core-shell nanoparticles embedded in 3D graphitized porous carbon network

A scalable and facile one-pot spray pyrolysis method combined with reduction process during hydrogen atmosphere at a low temperature of 400 °C is developed for the formation of Sn@SnO2-3DGHPC materials, in which Sn@SnO2 core-shell nanoparticles are uniformly anchored on a 3D graphitized hierarchical porous carbon network. In this constructed architecture, the SnO2 shell composed of single crystals could effectively not only facilitate the Li+/electrons transport but also alleviate mechanical stress caused by the large volume variation of internal Sn nanoparticles, while the 3D graphitized hierarchical porous carbon network with high electrical conductivity and mechanical stability can tightly capture the Sn@SnO2 nanoparticles and avoid direct contaction between them, thus leading to the internal integrity and structural stability of overall electrode materials. Consequently, this novel Sn@SnO2-3DGHPC anode exhibits high reversible capacity, outstanding cycling stability and rate capability.

Se-decorated SnO2/rGO composite spheres and their sodium storage performances

SnO2 is considered a promising anode material for sodium-ion batteries due to its high theoretical capacity and low cost. However, the poor electrical conductivity and dramatic volume variation during charge/discharge cycling is a major limitation in its practical applicability. Here we propose a simple one-pot spray pyrolysis process to construct unique pomegranate-like SnO2/rGO/Se spheres. The ideal structural configuration of these architectures was effective in alleviating the large volume variation of SnO2, besides facilitating rapid electron transfer, allowing the devised anode to exhibit superior sodium storage performances in terms of capacity (506.7 mAh/g at 30 mA/g), cycle performance (397 mAh/g after 100 cycles at 50 mA/g) and rate capability (188.9 mAh/g at an ultrahigh current density of 10 A/g). The experimental evidence confirms the practical workability of p-SnO2/rGO/Se spheres in SIBs.

Hierarchical yolk-shell CNT-(NiCo)O/C microspheres prepared by one-pot spray pyrolysis as anodes in lithium-ion batteries

This paper presents a hierarchical yolk–shell-structured microsphere comprising a hierarchical carbon nanotube (CNT)-(NiCo)O/C yolk and an embossed hollow thin shell (hereafter denoted as CNT-(NiCo)O/C microsphere) prepared by a one-pot spray pyrolysis process for potential use as an anode in lithium-ion batteries. During spray pyrolysis, the hierarchical CNT-(NiCo)O/C yolk, whose frame is linked with CNTs, is formed by mutual binding of the CNTs and size-controlled polystyrene (PS) nanobeads and subsequent selective decomposition of these nanobeads. Further, phase separation of melted poly(vinylpyrrolidone) facilitates the formation of the hollow shell. The discharge capacity of the CNT-(NiCo)O/C microspheres after 1000 cycles at an extremely high current density of 5.0 A g−1 is 598 mA h g−1. The CNT-(NiCo)O/C microspheres show reversible discharge capacities of 886, 709, 509, and 294 mA h g−1 at current densities of 0.5, 5, 20, and 50 A g−1, respectively. The unique nanostructure of the CNT-(NiCo)O/C microspheres with high electrical conductivity promotes the transfer kinetics of electrons and Li+ ions, which consequently leads to their improved electrochemical performances.

Strategy for synthesizing mesoporous NiO polyhedra with empty nanovoids via oxidation of NiSe polyhedra by nanoscale Kirkendall diffusion and their superior lithium-ion storage performance

A novel strategy for the synthesis of mesoporous metal oxide polyhedra with empty nanovoids by introducing nanoscale Kirkendall diffusion into a spray pyrolysis process is suggested. In this study, NiSe polyhedra with high index facets synthesized by one-pot spray pyrolysis were transformed into mesoporous NiO polyhedra with empty nanovoids by a facile oxidation process at 500 °C through nanoscale Kirkendall diffusion. Details of the formation mechanism of these uniquely structured NiO polyhedra were also studied. In the initial oxidation step, a thin NiO layer was formed on the surface of the NiSe polyhedra. The fast diffusion of Ni cations out through the NiO layer and the melting of the remaining metalloid Se formed a porous Se layer. The formation of a mesoporous NiO layer then enabled the penetration of oxygen gas by gas phase diffusion. The diffusion of metalloid Se into the mesopores of NiO and its reaction with oxygen gas formed SeO2 nanocrystals which then evaporated into the gas phase. The step-by-step oxidation of the NiSe crystals therefore resulted in mesoporous NiO polyhedra with empty nanovoids. When used as an anode material in a lithium ion battery, mesoporous NiO polyhedra with empty nanovoids showed superior cycling and rate performance compared to anodes fabricated from dense-structured NiSe polyhedra and commercial NiO nanopowders. The mesoporous NiO polyhedra showed a high discharge capacity of 1072 mA h g−1 after 200 cycles at a current density of 1.0 A g−1 and they showed a high reversible capacity of 453 mA h g−1, even at a high current density of 15.0 A g−1.

α-Fe2O3 anchored on porous N doped carbon derived from green microalgae via spray pyrolysis as anode materials for lithium ion batteries

The α-Fe2O3@nitrogen doped carbon (as donated α-Fe2O3@NC) composites derived from green microalgae was synthesized using one-pot spray pyrolysis, which showed a high discharge capacity of 1281.5mAhg−1 at 100mAg−1 as anode materials for lithium ion storage. They also provided good rate performance in a range of 200mAg−1–1000mAg−1, and maintained a capacity of 92% after 100 cycles at 200mAg−1. It demonstrated not only improved electrical conductivity but also effective prevention of the volume expansion of iron oxide during battery charge/discharge by uniformly forming iron oxide nanoparticles on microalgae via spray pyrolysis.

Synthesis of Cobalt Manganese Oxide-Carbon Nanotubes Composite Microspheres As a Bifunctional Cathode Catalyst for Li-O2 Batteries

Although lithium-ion batteries (LIBs) have been widely used in electronic devices, intercalation limits their energy densities, rendering them incapable of meeting the increasing demand for high energy density. Lithium-oxide (Li-O2) batteries are appealing energy storage and conversion devices owing to their remarkably high energy densities (~3500 Wh kg-1), ~8 times higher than those of current LIBs. However, despite great promise, Li-O2 batteries still suffer from low round-trip efficiency, poor cycle life, and voltage decay. It has been revealed that this limited electrochemical performance is mainly attributed to the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the oxygen electrode. The electrochemical performance of Li-O2 batteries is highly dependent on both the materials and architecture of the oxygen electrode. Transition metal oxide nanomaterials have attracted enormous interest as low-cost alternative catalysts to noble-metal catalysts capable of catalyzing both the ORR and OER. In particular, materials with mixed metal compounds play an important role in electrocatalytic reactions, since mixed valence species enhance electrocatalytic activity. However, the poor electronic conductivity limits the catalytic activity of the mixed-valant transition metal oxide. Therefore, nanostructured materials comprising efficient catalyst nanocrystals and carbon materials with high electrical conductivity, high electrocatalytic activities for the ORR and OER, and a well-designed porous structure to accommodate the reaction products have to be developed. A commercial air electrode should be formed by a simple printing process from slurry containing the cathode powders, organic binder, and solvent. Macroporous cathode powders with uniform composition, several microns in size, spherical morphology, and narrow size distribution should be used to form the uniform air electrode in the commercial process. However, studies on cathode microspheres with optimum morphological characteristics and high electrocatalytic activities for ORRs and OERs for Li–O2 batteries are rare. In this study, Mn-Co-O catalyst was studied as electrocatalyst showing high efficiencies for the ORR and OER for Li-O2 batteries. In addition, the optimum structure of carbon nanotube (CNT) microspheres was designed as efficient support material for catalysts with high electrical conductivity and high accommodation ability for Li2O2 products. Consequently, novel and uniquely structured CNT microspheres decorated with Mn-Co-O nanocrystals with a high electrocatalytic activity were designed and synthesized as cathode material for high performance Li–O2 batteries. Macroporous Mn-Co-O-CNT composite microspheres designed as efficient cathode material for Li-O2 batteries were prepared by one-pot spray pyrolysis. The macroporous structure of CNTs facilitated the wetting of the electrolyte and diffusion of oxygen within the electrode and provided plenty of space to accommodate Li2O2 species formed during the discharge process. The Li-O2 batteries with macroporous Mn-CO-O-CNT composite microspheres showed superior properties as cathode material. The new concept studied in this project can be efficiently applied to the development of highly efficient cathode materials for advanced Li-O2 batteries. Figure 1

Metal-Organic-Framework-Derived N-Doped Hierarchically Porous Carbon Polyhedrons Anchored on Crumpled Graphene Balls as Efficient Selenium Hosts for High-Performance Lithium-Selenium Batteries.

Developing carbon scaffolds showing rational pore structures as cathode hosts is essential for achieving superior electrochemical performances of lithium-selenium (Li-Se) batteries. Hierarchically porous N-doped carbon polyhedrons anchored on crumpled graphene balls (NPC/CGBs) are synthesized by carbonizing a zeolitic imidazolate framework-8 (ZIF-8)/CGB composite precursor, producing an unprecedented effective host matrix for high-performance Li-Se batteries. Mesoporous CGBs obtained by one-pot spray pyrolysis are used as a highly conductive matrix for uniform polyhedral ZIF-8 growth. During carbonization, ZIF-8 polyhedrons on mesoporous CGBs are converted into N-doped carbon polyhedrons showing abundant micropores, forming a high-surface-area, high-pore-volume hierarchically porous NPC/CGB composite whose small unique pores effectively confine Se during melt diffusion, thereby providing conductive electron pathways. Thus, the integrated NPC/CGB-Se composite ensures high Se utilization originating from complete electrochemical reactions between Se and Li ions. The NPC/CGB-Se composite cathode exhibits high discharge capacities (998 and 462 mA h g-1 at the 1st and 1000th cycles, respectively, at a 0.5 C current density), good capacity retention (68%, calculated from the 3rd cycle), and excellent rate capability. A discharge capacity of 409 mA h g-1 is achieved even at an extremely high (15.0 C) current density.

Design and synthesis of macroporous (Mn1/3Co2/3)O-carbon nanotubes composite microspheres as efficient catalysts for rechargeable Li-O2 batteries

Unique-structured (Mn1/3Co2/3)O-carbon nanotubes (MnCoO-CNT) composite microspheres synthesized by one-pot spray pyrolysis were studied as air electrode for lithium–oxygen (Li-O2) batteries. The (Mn1/3Co2/3)O nanocrystals were first introduced as efficient electrocatalysts for oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs). In addition, the optimum structure of CNT microspheres was designed as efficient support material for (Mn1/3Co2/3)O nanocatalysts with high electrical conductivity and high accommodation ability for Li2O2 products. The macroporous MnCoO-CNT composite microspheres exhibited excellent bifunctional oxygen catalytic activities in terms of a positive half-wave potential (0.67 V) for ORRs and high limiting diffusion current (35 mA cm−2 at 1.0 V) for OERs. When applied as a cathode material for Li–O2 batteries, the MnCoO–CNT microspheres delivered a high discharge capacity (37142 mA h g−1 at 200 mA g−1), excellent rate capability (4458 mA h g−1 at 2000 mA g−1), and long-term cycle stability (245 cycles at a capacity of 500 mA h g−1 at 200 mA g−1). The synergetic effect of macroporous CNT microspheres with high electrical conductivity and high electrocatalytic activities of the (Mn1/3Co2/3)O nanocatalyst were responsible for the superior performance of MnCoO–CNT composite microspheres as cathode material for Li–O2 batteries.

Excellent Li-ion storage performances of hierarchical SnO-SnO2 composite powders and SnO nanoplates prepared by one-pot spray pyrolysis

Hierarchical-structured SnO-SnO2 composite powders and SnO nanoplates with some SnO2 nanorods are prepared by one-pot spray pyrolysis. Dicyandiamide dissolved in the spray solution plays a key role in the preparation of the hierarchical-structured SnO-SnO2 composite powder and SnO nanoplates. The hierarchical-structured SnO-SnO2 composite powders, in which the SnO nanoplates are trapped in the porous SnO2 nanosphere, are prepared by spray pyrolysis at 800 °C. Sufficient conversion of the porous SnO2 nanospheres to SnO at 900 °C results in aggregation-free SnO2 nanoplates. SnO2 nanorods with a spherical nanodroplet at the tip are formed by Ostwald ripening. The hierarchical-structured SnO-SnO2 composite powder having high structural stability during repeated lithium alloying and dealloying reactions, shows superior discharge capacities and rate performances for lithium-ion storage compared to those of the dense-structured SnO2 powders. The discharge capacities of the hierarchical-structured SnO-SnO2 composite powders, SnO nanoplates with SnO2 nanorods, and dense-structured SnO2 powders at a current density of 1 A g−1 for the 300th cycle are 561, 504, and 416 mA h g−1, respectively. The SnO nanoplates with SnO2 nanorods and hierarchical-structured SnO-SnO2 powders deliver high reversible discharge capacities of 433 and 379 mA h g−1 at an extremely high current density of 10 A g−1, respectively.

Yolk–shell-structured (Fe0.5Ni0.5)9S8 solid-solution powders: Synthesis and application as anode materials for Na-ion batteries

Multicomponent metal sulfide materials with a yolk–shell structure and a single phase were studied for the first time as anode materials for sodium-ion batteries. Yolk–shell-structured Fe–Ni–O powders with a molar ratio of iron and nickel components of 1/1 were prepared via one-pot spray pyrolysis. The prepared Fe–Ni–O powders were transformed into yolk–shell-structured (Fe0.5Ni0.5)9S8 solid-solution powders via a sulfidation process. The initial discharge and charge capacities of the (Fe0.5Ni0.5)9S8 powders at a current density of 1 A·g−1 were 601 and 504 mA·h·g−1, respectively. The discharge capacities of the (Fe0.5Ni0.5)9S8 powders for the 2nd and 100th cycle were 530 and 527 mA·h·g−1, respectively, and their corresponding capacity retention measured from the 2nd cycle was 99%. The (Fe0.5Ni0.5)9S8 powders had high initial discharge and charge capacities at a low current density of 0.1 A·g−1, and the reversible discharge capacity decreased slightly from 568 to 465 mA·h·g−1 as the current density increased from 0.1 to 5.0 A·g−1. The synergetic effect of the novel yolk–shell structure and the multicomponent sulfide composition of the (Fe0.5Ni0.5)9S8 powders resulted in excellent sodium-ion storage performance.

Electrochemical properties of amorphous GeOx-C composite microspheres prepared by a one-pot spray pyrolysis process

Amorphous GeO2-GeO-C (GeOx-C) composite powders, containing a small amount of the GeC phase, are prepared by a one-pot spray pyrolysis process. The GeOx-C composite powders have a completely spherical shape and are non-aggregated. The Ge 3d components in the XPS spectrum of the composite occupy 53.3%, 40.1%, and 6.6% of the total for GeO2, GeO, and GeC, respectively. The amount of amorphous carbon in the GeOx-C composite powder is estimated at 18.3%, based on the TG and XPS analysis. The initial discharge and charge capacities of the GeOx-C composite powders at a current density of 1Ag−1 are 1873 and 908mAhg−1, respectively. The discharge capacities of the GeOx-C composite and commercial GeO2 powders for the 1200th cycle are 723 and 169mAhg−1, respectively, and their corresponding capacity retentions from the 2nd cycle are 70.1% and 19.0%, respectively. The high structural stability of the composite during repeated lithium insertion and desertion processes results in excellent long-term cycling performance.

Eco-Friendly Composite of Fe3O4-Reduced Graphene Oxide Particles for Efficient Enzyme Immobilization

A novel type of spherical and porous composites were synthesized to dually benefit from reduced graphene oxide (rGO) and magnetic materials as supports for enzyme immobilization. Three magnetic composite particles of Fe3O4 and rGO containing 71% (rGO-Fe3O4-M1), 36% (rGO-Fe3O4-M2), and 18% (rGO-Fe3O4-M3) Fe were prepared using a one-pot spray pyrolysis method and were used for the immobilization of the model enzymes, laccase and horseradish peroxidase (HRP). The rGO-Fe3O4 composite particles prepared by spray pyrolysis process had a regular shape, finite size, and uniform composition. The immobilization of laccase and HRP on rGO-Fe3O4-M1 resulted in 112 and 89.8% immobilization efficiency higher than that of synthesized pure Fe3O4 and rGO particles, respectively. The stability of laccase was improved by approximately 15-fold at 25 °C. Furthermore, rGO-Fe3O4-M1-immobilized laccase exhibited 92.6% of residual activity after 10 cycles of reuse and was 192% more efficient in oxidizing different phenolic compounds than the free enzyme. Therefore, these unique composite particles containing rGO and Fe3O4 may be promising supports for the efficient immobilization of industrially important enzymes with lower acute toxicity toward Vibrio fischeri than commercial pure Fe3O4 particles.

Hierarchical porous carbon spheres constructed from coal as electrode materials for high performance supercapacitors

Hierarchical porous carbon spheres (PCS) were prepared by a simple one-pot spray pyrolysis of coal oxide solution for use as supercapacitor electrode materials.

Electrochemical properties of P2-type Na2/3Ni1/3Mn2/3O2 plates synthesized by spray pyrolysis process for sodium-ion batteries

P2-type Na2/3Ni1/3Mn2/3O2 plates with homogeneous composition and regular morphology are prepared by spray pyrolysis. The rhombohedral P3-Na2/3Ni1/3Mn2/3O2 microspheres formed by one-pot spray pyrolysis transform into hexagonal P2-Na2/3Ni1/3Mn2/3O2 plates after post-treatment at temperatures between 800 and 1000°C. The mean size and thickness of P2-Na2/3Ni1/3Mn2/3O2 plates obtained after post-treatment at 900°C are 2.2μm and 550nm, respectively. The initial discharge capacities of P2-Na2/3Ni1/3Mn2/3O2 plates formed at 800, 900, and 1000°C at a current rate of 0.1C are 69, 86, and 80mA h g−1, respectively, while the discharge capacities after 200 cycles are 68, 80, and 76mAhg−1, respectively. However, the discharge capacities of P3-Na2/3Ni1/3Mn2/3O2 powders decrease from 62 to 50mAhg−1 after 200 cycles. P2-Na2/3Ni1/3Mn2/3O2 plates show low charge-transfer resistance and also exhibit better rate performance than P3-Na2/3Ni1/3Mn2/3O2 powders.

Selenium-impregnated hollow carbon microspheres as efficient cathode materials for lithium-selenium batteries

Se-impregnated hollow carbon (C-Se) microspheres were studied as cathode materials for Li-Se batteries. Hollow carbon microspheres containing micro- and mesopores were prepared by SnO2 leaching in the core-shell-structured SnO2@C composite microspheres prepared by one-pot spray pyrolysis. The mean size of the empty cores and the mean shell thickness of the hollow carbon microspheres were 490 and 90 nm, respectively. Metallic Se was impregnated into the hollow carbon microspheres by vapor inclusion. The Se content in the C-Se microspheres was measured by thermogravimetric analysis (TGA) to be 59.5 wt%. The discharge capacities of the C-Se microspheres in the 2nd and 1,000th cycles at a constant current density of 0.5 A g−1 were 603 and 525 mA h g−1, respectively, and the capacity retention measured from the 2nd cycle was 87%. The capacity retention of the C-Se microspheres measured from the 10th cycle was almost 100%. The structural stability of the C-Se composite microspheres during repeated Li-insertion and desertion process resulted in excellent Li-ion storage performance.