Glycine Combustion Research Articles

Heavily vanadium-doped LiFePO4 olivine as electrode material for Li-ion aqueous rechargeable batteries

Since LiFePO4 batteries play a major role in the transition to safe, more affordable and sustainable energy production, numerous strategies have been applied to modify LFP cathode, with the aim of improving its electrochemistry. In this contribution, a highly vanadium-doped LiFe0.9V0.1PO4/C composite (LFP/C-10V) is synthesized using the glycine combustion method and characterized by x-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Thermogravimetry Differential Thermal Analysis (TGDTA) and Cyclic Voltammetry (CV). It is shown that 10wt.% of vanadium can substitute Fe positions, thus decreasing unit cell volume, which is followed by generation of Li3V2PO4 traces, as detected by CV. High vanadium doping does not change the carbon content in the composite (≈13 wt%) but improves its electronic conductivity and electrochemical performance in both aqueous and organic electrolytes. The reversibility and current response are increasing following the trend: LFP/C, LFP/C -3mol%V, LFP/C - 5 mol % and LFP/C-10 mol %. The best specific capacity is obtained for the most highly doped olivine, which exhibits a reversible process at 1 mV s−1 in an aqueous electrolyte, thus showing a peak-to-peak distance of 56 mV. The high capacity of LFPC-10V is measured in both LiNO3 and NaNO3 electrolytes amounting to around 100 mAh g−1 at 20 mV s−1. Still, the material is only stable in LiNO3 electrolyte, making it more suitable for Li than Na-ion aqueous rechargeable batteries.

Fabrication of porous and highly defective CeO2-based catalysts for soot combustion with the strategy of soft-template addition and matrix doping by multiple rare earth elements

In this study, aiming to optimize the reactivity of CeO2 for soot combustion, rare earth elements (La, Pr, Sm and Y) co-doped CeO2 catalysts were synthesized via polyvinylpyrrolidone (PVP) and glycine (GNC) combustion methods. The PVP-CeO2-Re catalyst maintains a high specific surface area (82.9 m2 g−1) and abundant porous structure, thus being able to enhance the soot contact efficiency. The co-doping of multiple rare earth ions improves also the redox properties of the catalyst and increases the surface defects/vacancies, which is crucial to form the active surface O2- and O22- species to participate in soot combustion. The oxygen exchange rate over the catalyst with gaseous O2 can be accelerated by raising the temperature, and the exchange mechanism changes from a mixture of the R1 and R2 mechanisms to a domination by the R2 mechanism. Notably, PVP-CeO2-Re catalyst shows not only excellent activity (T50=373 °C) but also good stability. Our work could provide some reference for the design of promising catalysts applied in diesel particulate filters.

La/Mn molar ratio tuning the activity of La–Mn perovskites for CO and propane oxidation

A series of non-stoichiometric LaxMnO3 with La/Mn molar ratio x in the range of 0.80–1.2 have been prepared by a glycine combustion method and calcinated at 700 °C. The Mn-rich (x < 1) and La-rich (x > 1) catalysts presented higher and lower activity for CO and propane oxidation than the stoichiometric LaMnO3, respectively. The LaxMnO3 presented pure perovskite phase without La- or Mn-related phases detected even calcinated at 1000 °C. Notably, the 50% conversion temperature for CO and propane oxidation on the best La0·84MnO3 were around 70 and 35 °C lower than those on the stoichiometric LaMnO3, whereas which on the worst La1·15MnO3 were around 60 and 50 °C higher. The La0·84MnO3 possessing higher activity for CO and propane oxidation was predominately attributed to more Mn4+ cations, thus achieving abundant surface Mn4+–O bridge site as redox sites and surface Mn4+ sites as Lewis acidic sites, while the La1·15MnO3 owning lower activity for the reactions was primarily ascribed to less Mn4+ cations, and the lower reducibility of Mn4+ cations and surface adsorbed oxygens.

Controllably Modulating Oxygen Vacancies on Nonstoichiometric Nd−Ce−O Binary Oxides for Low‐temperature Oxidative Coupling of Methane

AbstractHerein, we synthesised a series of nonstoichiometric Nd−Ce−O composite oxides with a fluorite or rare‐earth C‐type phase structure using the glycine combustion method for the oxidative coupling of methane (OCM) reaction. As the amount of Nd3+ increases, the oxygen vacancies in this series of composite oxides gradually increase, leading to an amount increasing in the C2‐selective oxygen species O2− generated by the oxygen vacancies. In addition, with the increase in Nd3+, the number of moderate basic sites on the catalyst surface also improves, another significant factor affecting the OCM reaction performance of the composite oxides. Nd0.9Ce0.1O1.55 possesses optimal low‐temperature OCM reaction performance, achieving 8.0 % C2 yield at 450 °C and 14.1 % C2 yield at 700 °C. This can be attributed to the nonstoichiometric rare‐earth C‐type crystalline phase structure of Nd0.9Ce0.1O1.55, which exhibits the highest abundance of oxygen vacancies, selective oxygen species O2−, and moderate basic sites.

Magnetically separable Cu-Fe nanophotocatalyst with enhanced photocatalytic performance under visible-light irradiation: Optimizing the fuel type and heating approach in the synthesis process

This study aimed to examine the influence of fuel type and heating technique on the solution one-step solution combustion synthesis of CuFe2O4 spinel-type photocatalysts. The primary goal was to establish the best configuration of nanophotocatalysts with desirable characteristics, leading to improved photodegradation of dye pollutants when exposed to simulated solar radiation. Cu-spinel nanophotocatalysts were generated using a one-step combustion method involving three distinct fuels (urea, glycine, and citric acid) and two heating strategies (microwave and muffle furnace). The synthesized nanophotocatalysts were characterized through a range of tests, including XRD, FESEM, EDX, BET-BJH, FTIR, VSM, PL, DRS, and pHpzc analyses. During the simulated irradiation of sunlight, the efficacy of the Cu-spinel photocatalyst was evaluated using high-concentration Congo red, a widely used textile dye. Test results indicate that the Cu-spinel nanophotocatalyst formed utilizing glycine and microwave combustion displayed a desirable photocatalytic activity by degradation of 97 % of Congo red in 100 min. In addition, the photocatalytic efficiency of Congo red degradation was significantly enhanced compared to the other fuels and the conventional heating approach. Furthermore, CuFe(G-MW) demonstrated high stability throughout four cycles. Finally, a proposed mechanism for the degradation of Congo red using a CuFe(G-MW) nanophotocatalyst was presented.

Bismuth ferrite based acetone gas sensor: evaluation of graphene oxide loading.

We report a BiFeO3/graphene oxide (BFO/GO) perovskite, synthesized using a CTAB-functionalized glycine combustion route, as a potential material for acetone gas sensing applications. The physicochemical properties of the developed perovskite were analysed using XRD, FE-SEM, TEM, HRTEM, EDAX and XPS. The gas sensing performance was analysed for various test gases, including ethanol, acetone, propanol, ammonia, nitric acid, hydrogen sulphide and trimethylamine at a concentration of 500 ppm. Among the test gases, the developed BFO showed the best selectivity towards acetone, with a response of 61% at an operating temperature of 250 °C. All the GO-loaded BFO samples showed an improved gas sensing performance compared with pristine BFO in terms of sensitivity, the response/recovery times, the transient response curves and the stability. The 1 wt% GO-loaded BiFeO3 sensor showed the highest sensitivity of 89% towards acetone (500 ppm) at an operating temperature of 250 °C. These results show that the developed perovskites have significant potential for use in acetone gas sensing applications.

The structures, morphologies and intermediate-temperature electrochemical properties of CuO aided sintering Gd3+ and Ho3+ co-doped ceria electrolytes

In this study, a CuO-assisted sintering Ho3+ and Gd3+ co-doped CeO2 (Gd0.1Ho0.1Ce0.8O2-α-CuO, GHDC-CuO) electrolyte has been successfully synthesized using a citric acid and glycine combustion technique. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to observe and characterize the morphologies and structures of the produced samples. The XRD results showed that the doped samples' primary diffraction peaks were consistent with those of conventional cerium dioxide. The SEM findings demonstrated that adding the right quantity of CuO aided in the densification of the electrolytes. The total resistance was significantly impacted by the addition of CuO in the following order: R (1400-GHDC) > R (1450-GHDC) > R (1450-GHDC-CuO) > R (1400-GHDC-CuO). After being assembled into a thin film fuel cell, the maximum output power densities of 1400-GHDC-CuO (18 µm) using Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) as the cathode were 396 mW·cm-2 and 490 mW·cm-2 at 700 °C and 750 °C, respectively.

A-site cations tailoring the activity of LnMnO3 perovskites for CO and propane oxidation

To understand the role of A-site cations of perovskites on the reactivity, the LnMnO3 perovskites (Ln = La, Nd, Sm) with varied A-site cations were prepared by a facile glycine combustion method and evaluated for CO and propane oxidation. The activity for both reactions followed the trend: NdMnO3 > SmMnO3 > LaMnO3, demonstrating that lanthanide cations at A sites significantly affect the catalytic performance. Combined with Fourier transmission infrared spectra, temperature programmed reduction and desorption techniques, it was revealed that both the strength of Mn–O bonds and the adsorption of reactants played crucial roles on the activity for CO oxidation and C3H8 combustion on the LnMnO3. The adsorption of the reactants was responsible for the higher activity on the NdMnO3 than on the SmMnO3, while the strength of Mn–O bonds for the higher activity on the SmMnO3 than on the LaMnO3. The NdMnO3 possessed both weak Mn–O bonds and favorable adsorption of the reactants achieved the highest activity for CO oxidation and C3H8 combustion. The best NdMnO3 catalyst achieved CO and propane complete conversion at 160 and 360 °C, 90 and 60 °C lower than the LaMnO3, respectively.

Mesoporous LaNi1-xMnxO3 perovskite with enhanced catalytic performance and coke resistance synthesized via glycine-assisted spray pyrolysis for methane dry reforming

LaNiO3 perovskite is of great interest as a catalyst for methane dry reforming. Partial substitution of Ni with Mn can improve structural stability and lower carbon deposition. In this study LaNi1-xMnxO3 perovskite (x = 0, 0.4, and 1) was synthesized using glycine-assisted ultrasonic spray pyrolysis to modify the morphology of the product, which improved the overall performance of the catalyst in the methane dry reforming. Glycine combustion in the pyrolysis process significantly increased the catalyst specific surface area and it also changed the morphology from sub-micron solid spherical particles to hollow or shell-like particles. Mn significantly stabilized the perovskite structure and in the LaNi0.6Mn0.4O3, exsolved Ni nanoparticles decorated a perovskite substrate. Mn also increased the basic sites and helped to remove the carbon deposition. The lattice oxygen in the perovskite substrate can react with the deposited carbon and as a result, virtually no carbon was observed in the time-on-stream experiments at 700 °C and 20 h. The combined effect of Mn addition and the morphological features of the glycine-assisted perovskite resulted in significant improvement of the CH4 and CO2 conversion and stability of the catalyst.

Ruthenium Doped Lscf Based Cathode for Enhanced Performance of Solid Oxide Fuel Cells

Recently, a tremendous upsurge in the research of Solid oxide fuel cells (SOFCs) has been documented due to cheap electricity production and without harming the environment. The development of efficient SOFCs requires more robust cathode for oxygen reduction. Until yet a copious amount of research has been done on varieties of materials including LSCF. In this work, Ruthenium is doped on the LSCF forming nanostructured Ru-LSCF with various Ru stoichiometric quantities. The Ru-LSCF catalyst is prepared via simplistic technique “Glycine combustion process”, producing evenly embedded Ru in LSCF perovskite materials leading to increased oxygen reduction reaction (ORR). The nanostructured Ru-LSCF cathode showed polarization resistance of approximately 0.031 Ωm2 at 750 0C. The peak powers of approximately 1760.5, 1480.1, 893.3 mW/cm2 were recorded at 750, 700, and 650 0C, respectively. Ru LSCF was quantitatively optimized for enhanced power production with high precision calculation. The results show that the Ru-LSCF optimum fabricated nanostructured cathode is promising catalyst for the reduction of oxygen at the cathode side for highly durable SOFCs.

Activation of persulfate by LaFe1-xCoxO3 perovskite catalysts for the degradation of phenolics: Effect of synthetic method and metal substitution

The presence of resistant organic pollutants in environmental substrates requires the development and finding of novel decontamination methods. Advanced oxidation processes are among the most effective methods used for degradation of these pollutants through their oxidation and degradation into non-toxic and harmless, for the environment, final products. Ιn this research, a series of perovskites of ABO3-type, with La and Fe and/or Co in A and B positions respectively, LaFe1-xCoxO3 (x = 0, 0.25, 0.5, 0.75, 1), were synthesized with two different methods, a soft template method using anionic surfactant and by glycine combustion method and studied for their catalytic activity towards the degradation of phenolic compounds, a major class of environmental pollutants, through persulfate activation. The catalytic activity depended both by the B metal ion of perovskites and their ratio as well as by the synthesis method. LaCoO3 prepared with the anionic surfactant method, showed the highest catalytic activity with a rate constant of 0.024 min−1. Furthermore, the synthesis method also influenced the stability of perovskites as metal leaching studies showed that perovskites synthesized with the anionic surfactant showed greater stability. Quenching experiments were also used in order to shed light on the catalytic activation mechanism of persulfate for the degradation of phenolics. Overall, the results showed that the synthesis method can significantly affect the catalytic activity of the materials and their stability since the same materials synthesized with different methods show significantly different catalytic properties.

Enhanced antibacterial effect of CuFeO2 ceramic powders by glycine combustion process and visible light irradiation

Delafossite CuFeO2 ceramic powders with distinct sizes and morphologies of 1–6 μm/irregular shapes, 5–10 μm/faceted surfaces, and <100 nm/porous structures were prepared using solid-state reaction (SSR), NaOH hydrothermal (HT) synthesis, and glycine combustion (CB), respectively. X-ray diffractometric results indicated that the atmosphere of SSR dominated the phase transformations, revealing purified CuFeO2 only in Ar. The pH in HT could alternate the phase formations, and 2.28–3.35 M NaOH was the suitable solvent to obtain CuFeO2. For CB, the fuel of glycine (G) in metal nitrates (N) effectively determined the purity degree of CuFeO2, and a G/N ratio of 1.7 was appropriate to form CuFeO2. Antibacterial tests indicated that only 6000 and 6750 ppm CuFeO2 nanocrystallites by CB can effectively inhibit the growth and kill most Escherichia coli, respectively. Moreover, the killing rate of CuFeO2 nanocrystallites can be improved from 4 h to 2 h when irradiated by white light (1800 lux). Photocatalytic tests and optical measurements revealed that the bactericidal efficiency of CB CuFeO2 nanocrystallites can be enhanced by the reduction of minor Cu ions from +2 to +1 under white light irradiation.

NiMn mixed oxides with enhanced low-temperature deNOx performance: Insight into the coordinated decoration of MnOx by NiO phase via glycine combustion method

Herein, a facile glycine combustion method was utilized to prepare a series of Ni and Mn based single/double metal oxides, which were evaluated as catalysts for low temperature selective catalytic reduction of NO with NH3. The NiMn-T samples presented superior catalytic performance especially for NiMn-400, with ∼100 % NOx conversion, >85 % N2 selectivity within 90-300 °C, and better SO2 resistance. The superior catalytic activity might be related to the coordination of Ni and Mn, which afforded higher Mn4+/Mnn+ ratio, larger SBET, more suitable acid site amounts and redox capacity. The improved SO2 resistance of NiMn-400 catalyst can be ascribed to the less ammonium (bi)sulfate deposition and metal sulfation. In-situ DRIFTS revealed that the Ni doping could deliver more reactive species (NH2, monodentate nitrite, bidentate nitrate), and the surface acidity is less affected by SO2, which can account for the enhanced low temperature activity and SO2 resistance of the NiMn-400 catalyst.

Effect of Cl doping on the electrochemical performance of Sr2Fe1.5Mo0.5O6−δ cathode material for solid oxide fuel cells

In this paper, a novel Cl− anion doping strategy is proposed to modify the electrochemical performance of Sr2Fe1.5Mo0.5O6−δ (SFM) cathode for solid oxide fuel cells. A series of Cl-doped Sr2Fe1.5Mo0.5O6−x−δClx (SFMClx, x = 0, 0.1, 0.2, 0.3, 0.4) materials is synthesized by the citric acid–glycine combustion method, and the effect of Cl doping on the crystal structure and electrochemical performance is systemically investigated. The doping of Cl into the SFM leads to the lattice expansion, and the electrochemical performance of Cl-doped SFMClx cathodes is effectively improved as a result of the enhanced mobility of lattice oxygen introduced by Cl doping. The optimal composition with x = 0.2 (sample Sr2Fe1.5Mo0.5O5.8−δCl0.2, noted as SFMCl0.2) exhibits a minimum polarization resistance Rp value of 1.987 Ωcm2 at 600 °C, reduced by 38.04% compared with the SFM cathode. These results suggest that Cl doping is an effective strategy to improve the electrochemical properties of cathode for solid oxide fuel cells.

Research on the Properties of Solid Oxide Fuel Cells Based on Composite Cathode of YBaCo1.4Cu0.6-O5+δ-xSDC.

The new type of cathode material YBaCo1.4Cu0.6-O5+δ-xSDC (x = 20, 30, 40, 50 wt.%) was synthesized by sol-gel method, electrolyte material of Ce0.8Sm0.2O1.9 (SDC) and La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) were synthesized by glycine combustion, composite cathode materials were prepared by mixing the two materials evenly. The performance was analyzed using the ac impedance spectrum and SEM, the best performance was obtained with the ratio of x = 30%. After 2 hour sintering at 950 °C, YBCC-30%SDC cathode polarization resistance are 0.027 Ω · cm2, 0.043 Ω · cm2 and 0.074 Ω · cm2 at 850 °C, 800 °C, 750 °C, respectively. The performance of single battery YBCC-30SDC/LSGM/SDC/NiO-SDC was tested and the power density reached its maximum of 662 mW/cm2 at 850 °C.

Catalytic Wet Peroxide Oxidation (CWPO) of 2-Hydroxybenzoic acid and contaminated industrial effluent using LnMO3(Ln= La or Pr and M= Fe or Fe-Co)

The present study involves investigation of CWPO (Catalytic Wet Peroxide Oxidation) process for the removal of 2-Hydroxybenzoic acid (2-HBA or Salicylic acid), a moderate pollutant in industrial effluent. The best experimental conditions concerning selected varied parameters viz. pH, temperature were determined using hydrogen peroxide as oxidant in process. Different B-site substituted La and Pr based perovskite catalyst were synthesised via glycine combustion method. The structural analysis of the perovskite powders was monitored by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) was performed to analyse the morphology of solids. The images of SEM show distinct pores with particle size ranging between 50-280 nm. The results demonstrated CWPO of 2-HBA was largely influenced by B- site bimetallic catalyst (M = Fe-Co) at pH = 3.5, Cat[Conc.] = 20% and T = 100 °C, degrading 85-90% of the contaminant in 120 min, meanwhile for the B-site monometallic catalyst (M = Fe), the degradation was 80-88% under same reaction conditions. The catalytic performance of LnMO3(Ln = La or Pr and M = Fe or Fe-Co) was also performed for an industrial effluent. Presence of aromatic carboxylic acid derivatives in industrial effluent were confirmed by GC-MS analysis and were successfully degraded in the range of 80-85%.

Effect of Dy substitution on the Structural and Gas sensing Properties of BiFeO3

Facile synthesis of Dy substituted BiFeO3 were employed using Glycine combustion method. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) were employed to characterize the structure and morphology of the material. The effect of Dy doping on the crystalline structure, morphologies and gas sensing properties of the final products have been investigated. The gas sensing properties of Bi1−xDyx FeO3 (x = 0.00, 0.05) materials for semiconductor gas sensors are presented. For composition with x=0.05, sensor exhibited highest response (87%) towards acetone vapor at an operating temperature 250°C. The response and recovery time of the sensor for x = 0.05 were quite low (5sec and 40sec) respectively.

Enhanced and Facet-specific Electrocatalytic Properties of Ag/Bi2Fe4O9 Composite Nanoparticles.

Ag/Bi2Fe4O9 nanoparticles (BFO NPs) have been synthesized using a two-step approach involving glycine combustion and visible light irradiation. Their structures were characterized in detail using X-ray diffraction, transmission electron microscope, scanning electron microscopy, and scanning transmission electron microscopy techniques. Their electrocatalytic properties were studied through enzymatic glucose detection with an amperometric biosensor. The Ag deposited on selective crystal facets of BFO NPs significantly enhanced their electrocatalytic activity. To gain insights into the origin of the enhanced electrocatalytic activities, we have carried out studies of Ag+ reduction and Mn2+ oxidation reaction at the {200} and {001} facets, respectively. The results suggest effective charge separation on the BFO NP surfaces, which is likely responsible for the enhanced electrocatalytic properties. Furthermore, enhanced ferromagnetism was observed after the Ag deposition on BFO NPs, which may be related to the improved electrocatalytic properties through spin-dependent charge transport. The facet-specific electrocatalytic properties are highly interesting and desired for chemical reactions. This study demonstrates that Ag/BFO NPs are potentially useful for electrocatalytic applications including biosensing and chemical synthesis with high product selectivity.

Insights into the Redox Performance of Non–stoichiometric Lanthanum Manganite Perovskites for Solar Thermochemical CO2 Splitting

AbstractPerovskite structured mixed metal oxides are one category of redox materials that recently demonstrated high potential for solar fuel production from thermochemical H2O/CO2 splitting. Substituted lanthanum manganite perovskite was previously found to be one of the most suitable candidates among the perovskite family, owing to its unique redox properties. However, the effect of synthesis method and cationic substitutions in A and B‐sites of ABO3 perovskite need to be elucidated. Herein, a systematic study was performed by implementing various synthetic strategies such as solid‐state, pechini process, glycine combustion or glucose‐assisted methods, to obtain LaxSr1‐xMnO3 (LSM) as a single phase and to determine the effect of synthesis method on the redox efficiency and performance stability for CO2 splitting. The results indicated that the materials synthesized by the pechini method were the most reactive among the series, with a stable CO production of ∼260 μmol.g−1 for x=0.5. Also, various pure phase A and B‐site substituted perovskites were synthesized by the pechini method to study the effect of such substitutions on the fuel yield of these materials. Y/Ca/Ba A‐site and Al/Fe B‐site substitutions in (La,Sr)MnO3 did not enhance the redox cycling capability when compared with LSM. It was observed that Sr was the best A‐site substituent and the presence of single Mn cation alone in B‐site was the most suitable option for promoting CO2‐splitting activity. Further, the effect of the addition of promotional agents was explored and enhancement of CO evolution was observed when compared to pure LSM.

Photoluminescence, size and morphology of red-emitting Gd2O3:Eu3+ nanophosphor synthesized by various methods

Gd2O3:Eu3+ nanoparticles with doping concentration of 5% were prepared by urea-assisted combustion synthesis (UCS), carbohydrazide combustion synthesis (CCS), sucrose-aided combustion synthesis (SCS), glycine combustion synthesis (GCS) and by sol–gel (SG) synthesis. The nanopowders were postannealed at 1000°C for 3h to obtain nanocrystalline phosphor, which was confirmed by X-ray diffraction (XRD). Surface chemical groups were detected by Fourier transform infrared spectroscopy (FTIR). Particle size distribution and morphology images of the synthesized nanoparticles were obtained using transmission electron microscopy (TEM). Average particle size decreased exponentially with an increase in the amount of gases evolved during the synthesis method. Nanoparticles obtained by UCS showed the highest photoluminescence (PL) intensity, and absolute quantum yield (QY). A comparison of the factors affecting optical properties showed that PL intensity, QY and fluorescence lifetime were dependent on crystallite size.