Characterization of hydrogen storage behavior of the as-synthesized p-type NiO/n-type CeO2 nanocomposites by carbohydrates as a capping agent: The influence of morphology

This study proposes a p-type/n-type heterojunction system for electrochemically hydrogen storage. The electrochemical investigation was done as a simple method to evaluate storage capacity. The p-type NiO/n-type CeO₂ mesoporous nanocomposites were prepared via a facile thermal decomposition way that is better than the carbohydrates as a green capping agent. For the first time, the electrochemical hydrogen storage behavior of this nanocomposite was evaluated by chronopotentiometry technique in a potassium hydroxide aqueous solution (6 M KOH) under 1 mA current. The electrochemical measurements display that the hydrogen storage capacity is largely dependent on the design of the nanostructures. Sample No. 2 with the plate-like architecture has higher hydrogen storage capacity than sample No. 1 having particle architecture. The plate-like architecture increases the storage capacity by reducing the diffusion pathway, increasing the surface area, and buffering the volume change during cycling. The hydrogen storage capacity for sample No. 1 and 2 was obtained ≈5500 and 6850 mAh/g, respectively.     

Thermal decomposition synthesis,characterization and electrochemical hydrogen storage characteristics of Co3O4–CeO2 porous nanocomposite

Particle-like Co₃O₄–CeO₂ nanocomposite was synthesized via a facile thermal decomposition process in the presence of fructose as a green capping agent and ammonium cerium(IV) nitrate as Ce source. The effect of various parameters such as different cobalt sources, calcination temperature and time were investigated on the size and morphology of products. The transmission electron microscopy observations indicated that the synthesized products have a particle-like shape with an average diameter of 18–35 nm. For the first time, the electrochemical hydrogen storage performance of Co₃O₄–CeO₂ porous nanocomposite was investigated via chronopotentiometry method in aqueous KOH solution in this paper. The electrochemical measurements showed that this product has a good hydrogen storage capacity at room temperature. Its maximum discharge capacity was 5200 mAh/g after 20 cycles. Therefore, Co₃O₄–CeO₂ porous nanocomposite showed that it is a good candidate for electrochemical hydrogen storage.     

Synthesis,characterization and investigation of the electrochemical hydrogen storage properties of CuO–CeO2 nanocomposites synthesized by green method

Pure CuO–CeO₂ nanocomposites were synthesized by simple thermal decomposition method in presence of various Cu salts as a copper source and fructose as a green capping agent. In this study, the effect of various parameters such as the type of copper sources, temperature and time of reaction on the morphology and the particles size were studied. The products were characterized via X-ray diffraction (XRD) pattern, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), N2 adsorption (BET), vibrating sample magnetometer (VSM), and infrared spectrum (FT-IR). The optical property of the nanocomposite was examined via UV–vis (DRS) spectroscopy and the band gap was calculated to 3 eV. Also, the hydrogen storage capacity of CuO–CeO₂ nanocomposites and CeO₂ nanoparticles were investigated via chronopotentiometry method for the first time. The discharge capacity of CeO₂ nanoparticles and CuO–CeO₂ nanocomposites in 1 mA current and 20 cycles obtained 2150 and 2450 mAh/g, respectively.     

Facile precipitation synthesis and electrochemical evaluation of Zn2SnO4 nanostructure as a hydrogen storage material

A facile precipitation method with the subsequent thermal treatment has been developed for the synthesis of Zn₂SnO₄ nanostructures in presence of tetraethylenepentamine (TEPA) with long chain as a capping and basic agent. The effects of different parameters such as precursor of Zn, solvent, reaction time and temperature were studied to reach optimum size and morphology conditions. More importantly, through controlling the experimental conditions, three different morphologies of nanoparticle, nanorod and nanoplate Zn₂SnO₄ mesoporous through one reaction were successfully obtained. In this paper, hydrogen storage capacity of Zn₂SnO₄ nanoparticle reported for the first time. Furthermore, the mesoporous of Zn₂SnO₄ nanoparticle showed high electrochemical hydrogen storage capacities at room temperature. After 13 cycles, the discharging capacities of the electrode still remain above 4650 mAh/g. These results indicate that the mesoporous Zn₂SnO₄ nanoparticle may be potentially applied for electrochemical hydrogen storage.     

Green solid-state fabrication of new nanocomposites based on La–Fe–O nanostructures for electrochemical hydrogen storage application

Nano-sized La–Fe–O (LFO) structures were fabricated via novel free-solvent and green solid-state route using La (acac)₃. H₂O and Fe (acac)₃ complex precursors. Acetylacetonate (acac) in organometallic complex precursors control nucleation and growth of formed crystals with creation spatial barrier around the cations, and prevent nano-product agglomeration. The mechanism of role of acac has been explained in nanostructure formation. Changing of parameters in synthesis reaction consisting La:Fe molar ratio, calcination time and temperature in turn offer a virtuous control over the nanocomposites size and shape which various compositions of La₂O₃/LaFeO₃, LaFeO₃/La₂O₃ and LaFeO₃/Fe₂O₃ obtained. The as-prepared La–Fe–O nano-products were characterized thorough Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV–Vis, BET and energy dispersive X-ray (EDX) analysis in terms of crystallinity structure, composition, porosity and morphology. Different formed La–Fe–O nanostructures were evaluated for electrochemical hydrogen storage capacity through chronopotentiometry technique in stable current (1 mA). The achieved La–Fe–O nanoparticles could be applied as a favorable candidate active material for electrochemical hydrogen storage. Optical, magnetic and reducible characteristics of La–Fe–O nanostructures have positive effect on electrochemical hydrogen storage capacity. It was found out that the LaFeO₃/Fe₂O₃ nanocomposites have the best electrochemical hydrogen storage performance due to oxidation-reduction process of Fe²⁺/Fe³⁺ components which can help to charge-discharge process of hydrogen to increase the storage capability to 790 mAhg^?1 after 20 cycles. Also, the mixed metal oxides illustrate advanced discharge capacity than other binary oxides.     

Effect of copper phthalocyanine (CuPc) on electrochemical hydrogen storage capacity of BaAl2O4/BaCO3 nanoparticles

A green synthesis method, solution combustion, were performed to synthesize BaAl₂O₄/BaCO₃ nanoparticles by using stoichiometric amount of cations, Ba²⁺ and Al³⁺, in rational fraction of a fuel (maltose). Single fuel led to the formation of combustion reaction required further annealing at 700 °C in order to achieve pure crystals. The average crystallite sizes of the BaAl₂O₄/BaCO₃ nanopowders were obtained about 36 nm using modified Scherrer equation. In order to improve the electrochemical hydrogen storage capacity of BaAl₂O₄/BaCO₃ nanoparticles, a novel admixture was designed by introducing copper phthalocyanine (CuPc) into an inorganic phase. The reaction profiles of BaAl₂O₄/BaCO₃-CuPc nanocomposites were confirmed by FTIR analysis. The structural and elemental analysis were confirmed the formation of nanocomposites. Morphological analysis confirmed the nanoscale formation of the host material. In addition, TEM results clearly confirmed the morphology of BaAl₂O₄/BaCO₃ sample and its nanocomposites. The Band gap energy was calculated for host, CuPc and its respective nanocomposites using Tauc method obtained at 4.95, 2.10 and 2.54/4.89 eV, respectively. Electrochemical performances of the materials were confirmed a large I_pa for BaAl₂O₄/BaCO₃-CuPc nanocomposites as compare to the host materials. This was directly reflected in hydrogen storage capacities of the materials (900 mA h/g discharge capacity for BaAl₂O₄/BaCO₃ (～3.17%) and >1500 mA h/g for BaAl₂O₄/BaCO₃-CuPc nanocomposites (～5.3%)).     

Insight into effects of graphene and zinc oxide in Li4Ti5O12 as anode materials for Li-ion full-cell battery

Programmable design of nanocomposites of Li₄Ti₅O₁₂ (LTO) conducted through hydrothermal route in the presence of ethylenediamine as basic and capping agent. In this work, effect of ZnO and Graphene on the Li₄Ti₅O₁₂ based nanocomposites as anode materials investigated for Li-Ion battery performances. The full cells battery assembled with LTO based nanocomposites on Cu foil as the anode electrode and commercial LMO (LiMn₂O₄) on aluminum foil as cathode electrode. X-Ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FT-IR), along with Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission electron microscopy (TEM) images was applied for study the composition and structure of as-prepared samples. The electrochemical lithium storage capacity of prepared nanocomposites was compared with pristine LTO via chronopotentiometry charge-discharge techniques at 1.5–4.0 V and current rate of 100 mA/g. As a result, the electrode which is provided by LTO/TiO₂/ZnO and LTO/TiO₂/graphene nanocomposites provided 765 and 670 mAh/g discharge capacity compared with pristine LTO/TiO₂ (550 mAh/g) after 15 cycles. Based on the obtained results, fabricated nanocomposites can be promising compounds to improve the electrochemical performance of lithium storage.     

Study of hydrogen storage performance of ZnO–CeO2 ceramic nanocomposite and the effect of various parameters to reach the optimum product

ZnOCeO₂ nanocomposites have been successfully prepared by a simple sol-gel approach via employing fructose as a green capping agent. The effect of various parameters including the different precursors of zinc, calcination time and temperature on the morphology and size of as-synthesized products were investigated to reach the optimum conditions. Different analysis to study the synthesized products was utilized. We used X-ray diffraction (XRD) patterns to investigate the crystal structure of the products. The chemical composition of the nanocomposite was characterized by energy-dispersive X-ray analysis (EDX) and Fourier transform infrared (FT-IR) analyses. To study the size and morphology of nanocomposites were employed scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. The structural properties (porosity and specific surface area) of nanocomposite were evaluated by BET analysis. The performance of metal oxides as a host for hydrogen storage has not been widely studied. Albeit the technology of hydrogen energy enhanced gradually, the performance of metal oxides as a host for hydrogen adsorption has not been widely studied. According to our knowledge, the electrochemical hydrogen storage of prepared ZnOCeO₂ nanocomposite was investigated via chronopotentiometry method in KOH (6 M) electrolyte, for the first time. The maximum discharge capacity of the optimized product (S6) was observed at 2400 mAh/g after 20 cycles. The results showed the synthesized ZnOCeO₂ nanocomposites can be used as a suitable candidate for storage of energy in future.     

Effect of g-C3N4 amount on green synthesized GdFeO3/g-C3N4 nanocomposites as promising compounds for solid-state hydrogen storage

Hydrogen energy is a key role in novel renewable energy production/consumption technologies. Traditional hydrogen energy systems are suffered from low density, high production cost, low efficiency, and storage complications. With the start of solid-state hydrogen storage technology, many of above deficiencies are fulfilled, however, there are several unknown points, particularly in metal oxides, which need more attention. Hydrogen sorption on the layered materials or inside porous materials is a hopeful key to drawbacks for high-performance hydrogen sorption. Hereupon, layered solids with the merit of hydrogen sorption are introduced, for the first time, including “nanostructured bi-metal oxide (BMO)” and “graphitic carbon nitride (CN)”. Perovskites are ceramic and they are hard materials so they could be a favorable candidate for solid-state hydrogen storage. g-C₃N₄ has attractive features including high surface area, chemical stability, small band gap, and low-cost synthesis methods but also has great potential as an electrode material for energy storage capacitors. The main motivation for this study comes from the potential applications for perovskite materials and graphitic carbon nitride for the solid-state hydrogen storage method. The Perovskite type GdFeO₃ nanostructures (as BMO) synthesized through sol-gel approach in front of natural source of Grape juice as both complexing agent and fuel. The experimental scrutinization ascertains an original fabrication of GdFeO₃ (GF) nanostructures in Grape juice at 800 °C, with an approximately uniform nanosized structure of 70 nm on average. The obtained pure GF nanostructures are then utilized for nanocomposite formation based on g-C₃N₄ (CN) with different amounts. The resulting nanocomposites with the ratio of 1:2 from GF:CN perform a preferable hydrogen sorption capacity, in terms of “maximum discharge capacity of 577 mAhg^?1” in 2 M KOH electrolyte. It should be declared that however, the discharge capacity of the nanostructured GF is 188 mAhg^?1. It can be emphasized that these GF/CN nanocomposites can be utilized as hopeful hosts in an electrochemical hydrogen storage setup due to the synergic effect of g-C₃N₄ with essential characteristics in cooperation with BMO nanostructures as acceptable electrocatalysts.     

Dy3Fe5O12 and DyFeO3 nanostructures: Green and facial auto-combustion synthesis,characterization and comparative study on electrochemical hydrogen storage

Although the technology of hydrogen energy heightened gradually, the application of binary metal oxides as a host for hydrogen sorption has not been widely established. Here we show, with a facial combustion method, the formation of Dy₃Fe₅O₁₂ and DyFeO₃ nanostructures with maximum average particle sizes ranging from 25 to 30 and 16–18 nm, respectively. The physical properties of the samples were served which further reflect in hydrogen storage properties. The discharge capacities of Dy₃Fe₅O₁₂ and DyFeO₃ nanoparticles were obtained at 2000 and 2100 mA h/g, respectively. The hydrogen storage properties were confirmed in their respective current-voltage cycles, prior to chronopotentiometry.     

Novel synthesis of Zn2GeO4/graphene nanocomposite for enhanced electrochemical hydrogen storage performance

For the first time, a novel technique of preparing Zn₂GeO₄ nanostructures has been developed by using chemical precipitation method of GeCl₄ as a Ge precursor and acacen as a capping agent. Uniform and fine Zn₂GeO₄ nanoparticle was synthesized. The optimized Zn₂GeO₄ nanostructures anchored onto graphene sheets and Zn₂GeO₄/graphene nanocomposite synthesized through pre-graphenization, successfully. Hydrogen storage capacities of Zn₂GeO₄ nanoparticle and Zn₂GeO₄/graphene nanocomposite were compared, for the first time. Obtained results represent that Zn₂GeO₄/graphene nanocomposites have higher electrochemical hydrogen storage capacity than Zn₂GeO₄ nanoparticles. It was found that the synergistic effect between Zn₂GeO₄ nanoparticles and graphene sheets can improve the electrochemical performance of this hybrid composite electrode. After 29 cycles, the discharging capacities of the electrode reached to 2695 mAh/g. These results indicate that the Zn₂GeO₄/graphene nanocomposite can be potentially applied for electrochemical hydrogen storage.     

Hydrothermal synthesis of DyMn2O5/Ba3Mn2O8 nanocomposite as a potential hydrogen storage material

In this study, DyMn₂O₅/Ba₃Mn₂O₈ nanocomposites were prepared by hydrothermal route as potential hydrogen storage materials, for the first time. The effect of hydrothermal reaction time and calcination temperature was considered to achieve the optimum size and morphology. Although the knowledge of hydrogen energy propagated present days, the application of mixed metal oxide nanocomposites as a hydrogen sorbent has not been studied. The prepared nanocomposites with various sizes and morphologies were examined by scanning and transmission electron microscopies (SEM and TEM). X-ray diffraction (XRD), energy dispersive X-ray (EDX) and Fourier transform infrared (FT-IR) were carried out to consider purity and chemical compositions of nanocomposites. Amongst the hydrogen storage routes, electrochemical method is the best because of in situ hydrogen generation and storage at room pressure and temperature conditions. The electrochemical hydrogen storage performance of optimized nanocomposite was investigated in different currents of 0.5 and 1 mA. After 15 cycles, the discharging capacities of nanocomposite in currents of 0.5 and 1 mA were reported 760 and 1600 mAh.g⁻¹, respectively.     

Transformation of sluggish higher valent molybdenum into electrocatalytically active amorphous carbon doped MoO2/MoO3-x nanostructures using phyllanthus reticulatus fruit extract as natural reducing agent in supercritical fluid processing

Electrochemical hydrogen evolution by molybdenum dioxide and molybdenum sub-oxides has gathered much attention owing to their excellent stability and high catalytic activity. However, the reduction of higher valent molybdenum oxides to lower valent molybdenum oxides using conventional chemical process is a challenging issue. Here, supercritical fluid (SCF) and hydrothermal assisted direct synthesis of carbon doped lower valent molybdenum oxides i.e., MoO₂/MoO_3-x using ammonium heptamolybdate tetrahydrate and phyllanthus reticulatus fruit extract is demonstrated. The phyllanthus reticulatus fruit extract was used as natural reducing agent and it facilitated the reduction, nucleation and surface capping of lower valent molybdenum oxides. XRD and XPS analysis confirmed the phase pure monoclinic MoO₂ nanostructures formation with mildly oxidized molybdenum suboxides (MoO_3-x) thin layer on the surface. The partial conversion of phyllanthus reticulatus fruit extract to carbon nanostructures that were doped in MoO₂/MoO_3-x nanostructures was further confirmed using Raman spectroscopic analysis. The carbon doped MoO₂/MoO_3-x nanostructures prepared by SCF and hydrothermal method exhibited superior electrochemical hydrogen evolution reaction with the low overpotential of 160 and 207 mV at a current density of 10 mA cm⁻², respectively.     

Barium cobaltite nanoparticles: Sol-gel synthesis and characterization and their electrochemical hydrogen storage properties

The study of the effect of different chelating agents in the Pechini method on the morphology has been a promising strategy that can be used for practical tuning of the nanoparticle's morphology and hence the electrochemical hydrogen storage capacity. In the current study, the conventional Pechini sol-gel approach was used to prepare the Ba₂Co₉O₁₄ nanoparticles as a novel hydrogen storage material. The X-ray diffraction investigation approved the formation of Ba₂Co₉O₁₄ with a Hexagonal crystal structure for all of the synthesized samples. The scanning electron microscopy (SEM) revealed when citric acid was used as a chelating agent, nanoparticles with finer and more uniform morphology were obtained rather than other chelating sources. The transmission electron microscopy (TEM) showed in the presence of citric acid; the size of the synthesized nanoparticles was between 14 and 24 nm. According to the Diffuse Reflectance Spectroscopy (DRS) analysis, the calculated bandgap of synthesized nanoparticles was approximately 3.2 eV, which indicates that synthesized nanoparticles were semiconductors in essence. The electrochemical hydrogen adsorption/desorption results showed that the sample synthesized by the citric acid has an enhancement in electrochemical hydrogen storage of approximately 800 mAh/g after 15 cycles.     

Synthesis of potential nanostructures based on strontium hexaferrite for electrochemical hydrogen storage

Today, the reduction of fossil fuel resources and the increase of their destructive environmental effects are important challenges. One strategy to this problem is application of new sources of energy supply. Hydrogen can play an important role in future energy supplies due to its unique properties such as clean combustion and high energy content relative to mass. In addition, hydrogen is considered as a green energy because it can be produced from renewable sources and is not polluting. The most important issue in hydrogen as a fuel is its storage. Hydrogen must be stored reversibly in a completely safe manner as well as with high storage efficiencies. One of the best ways to store hydrogen is using of new nanostructured adsorbents. In this study, first strontium hexaferrite (SrFe₁₂O₁₉) nanostructures are synthesized by sol-gel auto-combustion method. Then, the samples structure is studied using various techniques. Furthermore, the nanostructures are used as hydrogen storage materials. Using electrochemical techniques, the hydrogen storage properties of the materials are investigated in alkaline media. The obtained electrochemical results show that the maximum hydrogen storage capacity of SrFe₁₂O₁₉ nanostructures is about 3100 mAh/g.     

Green synthesis of DyBa2Fe3O7.988/DyFeO3 nanocomposites using almond extract with dual eco-friendly applications: Photocatalytic and antibacterial activities

For the first time, photocatalytical and antibacterial activities of DyBa₂Fe₃O_7.988/DyFeO₃ (Dy-Ba-Fe-O) nanocomposites as eco-friendly applications of this compound was studied in the same time. Since the applications of this compound are eco-friendly, ultrasound technique was chosen as the synthesis method. Achieving the pure product with good crystallinity with the lowest energy consumption can be considered as one of the advantages of this work. Using the almond core extract as a natural reagent was another reason for consideration this method as a green process. Band gap of this nanocomposite was estimated about 2.6 eV that showed this product can be used as a visible-active photocatalyst. Rhodamin-B dye as an organic pollutant model using the as-prepared nanocomposite was degraded about 72% that was a considerable result under visible irradiation. Elimination of microorganisms was studied by disc diffusion to recognize the sensitivity of bacterial (Staphylococcus aureus, Bacillus subtilis, E. coli, K. pneumonia and P. aeruginosa) strains the manufactured. The results confirmed that DyBa₂Fe₃O_7.988/DyFeO₃ (DBFeO) nanocomposites can be used as an antibacterial agent because of the manifested strong antibacterial ability upon Gram-negative pathogens such as K. pneumonia and E. coli. The properties of this product were characterized by different analyses including SEM, XRD, EDS, FT-IR, DRS and TEM.     

Green synthesis,characterization and investigation of the electrochemical hydrogen storage properties of Dy2Ce2O7 nanostructures with fig extract

Nanostructured Dy₂Ce₂O₇ with good electrochemical hydrogen storage properties has been produced utilizing a novel and green method in the presence of fig extract, for the first time. Fig extract has been employed as novel kind of fuel in the production of pure Dy₂Ce₂O₇. By varying the notable factor, temperature for production, Dy₂Ce₂O₇ structures can be created that are different in morphological features and Coulombic efficiency as well as electrochemical hydrogen storage properties. Diverse techniques have been adopted to examine and characterize the formed Dy₂Ce₂O₇ with the aid of fig extract. Electrochemical hydrogen storage features of the diverse Dy₂Ce₂O₇ samples (formed with the aid of fig extract) have been compared with chronopotentiometry technique at potash solution. Our findings reveal that the nanostructured Dy₂Ce₂O₇ fabricated with the aid of fig extract at 400 ^°C can possess the best efficiency for store hydrogen. Usage of fig extract, the new and eco-friendly fuel, for synthesis of the nanostructured Dy₂Ce₂O₇ that is efficiently capable to store hydrogen (renewable type of energy carrier), can be helpful to decline and stop the environmental pollution.     

Gd3Fe5O12/MgAl-LDH nanocomposites: Sonochemical synthesis,optimization and electrochemical hydrogen storage studies

The development of an eco-friendly and pollution-free hydrogen storage cell power system has received considerable research attention in recent years. Several prominent developments in energy storage mechanisms have been made during the last decade, influencing innovation, exploration, and the probable path for improving energy storage knowledge. We propose a hydrogen energy storage system based on novel electrode materials and electrochemical methods. A series of nanocomposites based on MgAl-LDH and Gd₃Fe₅O₁₂ garnet were designed as active materials. Ultrasonic radiation was used for the synthesis of Gd₃Fe₅O₁₂/MgAl-LDH nanocomposites. Structures of Gd₃Fe₅O₁₂ without any impurities were achieved by sonication power of 90 W/cm² while the synthetic sample without sonication power led to the synthesis of Gd₃Fe₅O₁₂ in the presence of GdFeO₃ phase. The hydrogen storage capacity for pristine MgAl-LDH and Gd₃Fe₅O₁₂ was measured at 213 and 388 mAhg⁻¹ after 15 cycles, respectively. Then, capacity for Gd₃Fe₅O₁₂/MgAl-LDH nanocomposites increased to 316 mAhg⁻¹ at current of 1 mA in 15th cycles. Newly developed electrode materials such as Gd₃Fe₅O₁₂/MgAl-LDH with mechanisms such as spillover, redox and physical adsorption are excellent candidates for energy storage power systems.     

Synthesis of strontium chromate-nitrogen and sulfur co-doped graphene and its potential for electrochemical hydrogen storage

In the present study, monazite-type strontium chromate (SrCrO₄) as a ternary metal oxide was prepared by the sol-gel method. Nitrogen and sulfur co-doped graphene decorated with SrCrO₄ nanocrystals was synthesized successfully, and the electrochemical hydrogen storage performance of the SrCrO₄ and its relative nanocomposites also were investigated by chronopotentiometry (CHP) technique. The effect of doped graphene as a substrate of the SrCrO₄ sample on the improvement of the electrochemical hydrogen storage performance was considered as well. The SrCrO₄-nitrogen and sulfur co-doped graphene (SrCrO₄/NSG) displayed the highest discharge capacity in comparison to SrCrO₄-reduced graphene oxide (SrCrO₄/rGO), SrCrO₄ calcined at 1000 °C (SrCrO₄ (1000)) and SrCrO₄ calcined at 800 °C (SrCrO₄ (800)). Also, increasing the hydrogen storage capacity of the samples by repeating the cycles indicated the excellent cycle stability of the nanoparticles. In monazite-type structures, oxygen vacancies can be created by thermal treatment. Creating oxygen vacancies can improve redox reactions, which increase the conductivity of the samples and hydrogen storage capacity.     

Ultrasonic assisted synthesis of a nano-sized Co2SnO4/graphene: A potential material for electrochemical hydrogen storage application

A facile and rapid sonochemical method has been developed for the synthesis of Co₂SnO₄ nanostructures in presence of glucose as a green capping agent, for the first time. The effect of different parameters such as ultrasonic irradiation, time irradiation, basic agent and solvent were studied to reach optimum size and morphology conditions. The optimized Co₂SnO₄ nanostructures anchored onto graphene sheets and Co₂SnO₄/Graphene nanocomposite synthesized through pre-graphenization, successfully. In this paper, hydrogen storage capacity of optimized Co₂SnO₄ nanostructures and Co₂SnO₄/Graphene nanocomposite compared for the first time. Co₂SnO₄/Graphene nanocomposite show more excellent electrochemical performance than pure Co₂SnO₄ nanoparticles. It was found that the synergistic effect between Co₂SnO₄ nanoparticles and graphene sheets can improve the electrochemical performance of this hybrid composites electrode. After 25 cycles, the discharging capacities of the Co₂SnO₄ nanostructure and Co₂SnO₄/Graphene nanocomposite electrode reach 1190 and 2700 mAh/g, respectively.