One-step Solution Combustion Synthesis Research Articles

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.

KCl-assisted rapid and low-cost synthesis of antiperovskite (Fe1-xCux)4N anchored on Cu2O nanosheets for highly efficient electrochemical overall water splitting

Developing bifunctional electrocatalysts with abundant reserves and efficient performance is significant for alkaline water electrolysis. Herein, the antiperovskite nitride (FexCu1-x)4N particles anchored on the surface of Cu2O nanosheets have been synthesized by one-step solution combustion synthesis with the assistance of KCl. The (FexCu1-x)4N interacts with Cu2O in the form of p-n junction. Such an assembly effectively promotes the charge transfer under the interval built-in field, which can regulate the electronic densities to greatly increase the reaction kinetics and available active sites. Moreover, the electrocatalysts experience the different structural evolution during HER and OER process. The in-situ reconstructed species possess a proper free energy of adsorbed intermediates for highly efficient bifunctional electrocatalysis via DFT calculation. The optimal (Fe1-xCux)4N-Cu2O heterostructure couples show a superior bifunctional performance for water electrolysis, with a low cell voltage of 1.57 V at 10 mA cm−2 and nearly 100 % Faraday efficiency, surpassing the benchmark precious metal couples.

Hollow macroporous CeO2/β-Bi2O3 heterostructure sphere via one-step spray solution combustion synthesis for efficient photocatalysis

The spherical CeO2/β-Bi2O3 heterostructure with the hollow macroporous structure was synthesized by a simple one-step spray solution combustion synthesis (SSCS). The microstructure, phase composition and optical characteristics of the synthesized samples were investigated by HRTEM, FESEM, BET, XPS, DRS and other characterization methods. The results demonstrate that the prepared samples had a particle diameter of about 1–5 µm and the grain size of around 5.4 nm. The photocatalytic activity of the spherical CeO2/β-Bi2O3 was investigated by visible light degradation of RhB (97.22% in 120 min). Additionally, the heterojunction had a broader visible light absorption in the 400–700 nm range, a substantial red-shift in the absorption edge, and a smaller band gap of 2.54 eV compared to pure CeO2 or β-Bi2O3 materials made using the traditional SCS approach. The spherical shape and large specific surface area (54.625 m2·g−1) of the synthesized heterojunction allow for better coupling of CeO2 with β-Bi2O3, which further reduces the luminescence intensity, enhances light collection and charge transfer, and exposes more surface defects to achieve improved photocatalytic performance. Calculations using density functional theory (DFT) demonstrate that the heterojunction can speed up interfacial charge transfer and reduce the recombination of photogenerated charges, causing the reactants to undergo deep oxidation.

One-step solution combustion synthesis of Bi/BiOCl nanosheets: Reaction mechanism and photocatalytic RhB degradation

In this study, Bi/BiOCl nanosheets were prepared by a rapid, cost-efficient and one-step solution combustion synthesis method using a mixed fuel (glycine and tartaric acid). Through thermometry and thermogravimetric analysis/differential scanning calorimetry (TGA-DSC), the combustion mode and reaction mechanism are analyzed. The reducing gas produced by the mixed fuel is a necessary condition for obtaining metal Bi decorated BiOCl, and the content of Bi in the composite can be regulated by adjusting the molar ratio of Bi/Cl in reactants. In addition, under visible light irradiation, due to the SPR effect of metal Bi, Bi/BiOCl composite photocatalyst shows better photocatalytic performance, in which the highest degradation efficiency of Rhodamine B (RhB) within 120 min is 2.6 times higher than that of BiOCl. Thus, the present study provides an economic and convenient method for the tunable synthesis of a high-efficiency catalyst for the degradation of pollutants.

Rational competent electrocatalytic oxygen evolution reaction on stable tailored ternary MoO 3 ‐NiO‐activated carbon hybrid catalyst

Rational designing of advanced electrocatalysts for oxygen evolution reaction (OER) for energy sustainability is challenging. In this perspective, the fabrication of an efficient ternary hybrid composite electrocatalyst consisting of carbon-based materials and earth-abundant metal oxides can be thought as a better choice for large-scale applications. Hybrid of MoO3 and NiO with carbon material would possibly improve stability and conductivity which can assist in improving OER performance. In this regard, we report the development of MoO3/NiO/activated carbon (MoNiAC) ternary hybrid catalyst by a facile, one-step solution combustion synthesis (SCS) method. The physiochemical properties of the synthesized catalyst were evaluated by advanced analytical and spectroscopic techniques. The MoNiAC ternary hybrid catalyst exhibited a lower over-potential (279 mV) (without iR compensation) to attain the current density of 10 mA/cm2, and small Tafel slope of 89 mV/dec was accompanied. The superior activity could be ascribed to the synergism between MoO3, NiO, and AC. Furthermore, the stability graph of the hybrid demonstrated appreciable durability of catalyst for upto 8.33 h. The characterization of after stability catalyst suggested no major disturbance in the morphology as well as element distribution signifying the high durability of the hybrid catalyst in terms of activity as well as morphology. The remarkable features such as appreciable OER activity, promising kinetics, and robustness ameliorated the performance of MoNiAC hybrid as an electrocatalyst for OER.

One-step solution combustion synthesis of micro-nano-scale porous Cu/CeO2 with enhanced photocatalytic properties

The Cu/CeO2 nanoporous composite material was prepared via a one-step and energy-saving method of solution combustion synthesis (SCS). The phase composition, surface morphology and optical characteristics of Cu/CeO2 were studied. The results show that the SCS products are composed of cubic fluorite CeO2 and Cu. Due to the generation and escape of gas during the synthetic reaction, the SCS CeO2 shows porous structure, in which the mesopores (diameter 10–17 nm) nest in the wall of large pores (diameter 80–300 nm). X-ray photoelectron spectroscopy (XPS) outcomes indicate that the oxygen vacancy concentration of CeO2 increases (18.97%–30.93%) with the increase of Cu concentration. The decoration of Cu greatly enhances the catalytic activity of CeO2 nanomaterials. 30 wt% Cu/CeO2 composite material shows the best photocatalytic activities for the degradation of methyl orange (MO) (95.99%), which is about 4.3 times that of CeO2 at the same time (120 min). UV-vis diffuse reflectance spectroscopy (DRS) results show that the semiconductor band gap is reduced with the addition of metallic Cu, which leads to the enhancement of photocatalytic activity. The free radical trapping experiments demonstrate that ·O2– and h+ are the main active species in the photocatalytic degradation of MO. Based on the above results, a hypothesized mechanism for enhanced photocatalysis of Cu/CeO2 nanomaterials was proposed: the porous structure provides more reactive sites and channels for mass transfer, and the presence of metallic Cu improves the oxygen vacancy concentration of CeO2 and then promotes charge-carrier separation, which helps enhance the photocatalytic performance of Cu/CeO2.

One-Step Solution Combustion Synthesis of Bi/Biocl Nanosheets: Reaction Mechanism and Photocatalytic Properties

One-Step Solution Combustion Synthesis of Bi/Biocl Nanosheets: Reaction Mechanism and Photocatalytic Properties

Accelerated crystallization of CuAlO2 delafossite phase by controlling thermal regime during solution combustion synthesis

In the present study, for the first time, CuAlO2 delafossite phase was successfully obtained through a one-step solution combustion synthesis (SCS) process. Moreover, in order to accelerate CuAlO2 crystallization, two-step process, i.e. SCS followed by heat-treatment (different thermal regimes: continuous and discontinuous) without controlling the atmospheric oxygen, was applied. In the two-step process, heating time duration needed for the crystallization of CuAlO2 was lowered to 30 min at 1100 °C by exerting SCS on the mixture of starting materials. It was found that different thermal regimes can highly affect the formation of CuAlO2 phase. Furthermore, according to the SEM and TEM studies, it was revealed that the resultant powders have a flaky-shape morphology with lamellar structure.

One-Step Solution-Combustion Synthesis of Ni/NiO Nanocomposites Using 6-Aminohexanoic Acid as a Fuel: Effect of Oxidizer-to-Fuel Ratio

One-Step Solution-Combustion Synthesis of Ni/NiO Nanocomposites Using 6-Aminohexanoic Acid as a Fuel: Effect of Oxidizer-to-Fuel Ratio

Single-Step Solution-Combustion Synthesis of Magnetically Soft NiFe2O4 Nanopowders with Controllable Parameters

One-step solution-combustion synthesis with glycine as a fuel was used to obtain ferromagnetic nickel ferrite (NiFe2O4) spinel. According to EDX data, the elemental composition of all synthesized samples corresponded to NiFe2O4, while the XRD results showed the formation of phase-pure nickel ferrite spinel. NiFe2O4 nanopowders had a branched porous microstructure as established by SEM analysis. Variation in the Red/Ox ratio (glycine to nitrate ratio G/N = 0.4, 0.6, 0.8, 1.0, 1.2) was found to affect the average size of nickel ferrite crystallites (D) within the range 23–37 nm. The results of vibration magnetometry showed the ferromagnetic ordering in magnetic moments of NiFe2O4 nanopowders. The magnetic parameters of synthesized nickel ferrite—saturation magnetization Ms = 31–59 emu/g, remanent magnetization Mr = 3–13 emu/g, and coercive force Hc = 10–95 Oe—were found to depend on crystallite size D. The fact that the values of Ms, Mr, and Hc grow with increasing D opens up a way to synthesis of NiFe2O4 nanopowders with controllable magnetic parameters by simply varying the G/N ratio of starting solution.

One-step solution combustion synthesis and characterization of ZnFe2O4 and ZnFe1.6O4 nanoparticles

One-step solution combustion of ZnFe2O4 and ZnFe1.6O4 nanoparticles was represented. To obtain a better dispersion of nanoparticles with high specific surface area values, salt-assisted solution reaction was applied using KCl as a key criterion. Structure, chemical composition, microstructure, photoluminescence emissions, magnetic properties, and band gap of the samples were also studied. Results showed that ZnFe2O4 and ZnFe1.6O4 crystalline phases were synthesized in a one-step combustion reaction without any post-heating process requirement. The cation distributions amongst tetrahedral and octahedral sites in samples were estimated by modified Bertaut method using XRD data. Both stoichiometric and non-stoichiometric zinc ferrites had a partial reverse spinel structure with high degree of inversion. FTIR spectra demonstrated some bands associated with Fe–O and Zn–O bonds. Moreover, no unwanted impurity such as nitrate was detected in synthesized powders. Microstructure and nitrogen adsorption/desorption studies showed that the synthesized powders were mesoporous with high specific surface area, together with agglomerated nanoparticles. Magnetization curves showed that both ZnFe2O4 and ZnFe1.6O4 samples were superparamagnetic materials.

Spray solution combustion synthesis of hollow porous MoO3 photocatalyst

Abstract The hollow spherical MoO 3 photocatalyst was successfully prepared by a facile one-step spray solution combustion synthesis method (SSCS). Ammonium molybdate (AHM) and urea were used as the oxidant and fuel, respectively. The MoO 3 with crystallized orthorhombic phase was detected by the X-ray diffractions. And there were many pores on MoO 3 spherical shells shown in SEM results, created by the infiltration of NO 2 and CO 2 during the reactions. Furthermore, an illustration of the MoO 3 stepwise reaction process was proposed. The MoO 3 photocatalysts showed excellent photocatalytic degradation efficiencies over rhodamine B (RhB) under visible-light irradiation, and M4 sample synthesized at 600 °C with the urea/AHM ratio of 4 showed the highest photocatalytic degradation efficiency (82% within 60 min).

Noble-metal-free NiCu/CeO2 catalysts for H2 generation from hydrous hydrazine

The development of cost effective catalysts with high activity and 100% selectivity for hydrogen generation from the decomposition of hydrous hydrazine, a promising liquid-phase hydrogen carrier, is a critical challenge for the practical application of hydrous hydrazine to fuel cell vehicles. In this study, noble-metal-free NiCu/CeO2 bimetallic catalysts were readily synthesized using one-step solution combustion synthesis (SCS). The addition of Cu to Ni/CeO2 exhibited a synergistic effect to enhance the catalytic activity for the reaction. Catalyst characterization revealed that the improvement of catalytic performance is attributed to a combination of NiCu alloying, particle size of the active component, and formation of oxygen vacancy in the CeO2 lattice. The tailored 13 wt% Ni0.5Cu0.5/CeO2 catalyst exhibited 100% H2 selectivity in the temperature range 30–70 °C and 3.2-fold higher turnover frequency (TOF) of 1450.0 h−1 at 50 °C as compared to of the Ni/CeO2. This reactivity is also superior to that of most reported non-noble metal catalysts and is even comparable to noble metal-based catalysts.

One-step solution combustion synthesis of K0.5Na0.5NbO3 powders at a large-scale

In this work, fine powders of K0.5Na0.5NbO3 (KNN) are produced by a single step of solution combustion synthesis (SCS) using glycine as the reductant fuel and potassium & sodium nitrates as the oxidizers, which are mixed with niobium oxide. Single phase of KNN products can be successfully prepared in a one-step SCS by adjusting the glycine-nitrate ratio. It is concluded that the stoichiometric or slightly fuel-excess condition is good for the single step production of KNN. The one-step SCS of KNN also shows good scaling-up productivity, which can be ignited by both electric heating and microwave heating. This work may provide a feasible large-scale production of various functional oxides by a one-step SCS process.

One-step salt-assisted solution combustion synthesis of Ni-based composites for use as supercapacitor electrodes

Low cost mass production of Ni-based composites on an industrial scale with high electrochemical performance is of practical interest for supercapacitors. In this report, various Ni-based composites containing Ni2(CO3)(OH)2, Ni3(NO3)2(OH)4, NiC2O4 or NiO have been successfully synthesized via a one-step salt-assisted solution combustion synthesis at a temperature of 215 °C. The morphology and chemical composition of the as-obtained products can be controlled by monitoring the reaction parameters inclusive of the initial concentration of salt solution, and salt species. NC-1.0 composite obtained by salt-assisted solution combustion synthesis delivers higher specific capacitance (1420 F g−1 at 1 A g−1), and better cycling performance (60.0% after 2000 cycles) than those of NC-0.0 (1260 F g−1 at 1 A g−1, 53.6% after 2000 cycles) achieved by conventional solution combustion synthesis. Hybrid supercapacitor with NC-1.0 composite as positive electrode and active carbon as negative electrode delivers high energy density (32.5 Wh kg−1 at a power density of 310.2 W kg−1). The performance of the obtained Ni-based composites as supercapacitor electrodes demonstrates their potential for upcoming electronic devices.

Rapid preparation of α, β-Bi2O3 and α/β-Bi2O3 heterojunction with enhanced photocatalytic properties

α-Bi2O3 and β-Bi2O3 nanoparticles were selectively synthesized via one-step solution combustion synthesis (SCS) using bismuth nitrate (Bi(NO3)3·5H2O) as the oxidant and tartaric acid (C4H6O6) as the fuel, and α/β-Bi2O3 heterojunction was rapidly prepared by treating SCS β-Bi2O3 powders with NaOH solution. The physical and chemical properties of as-prepared samples were characterized by XRD, SEM, TEM, PL, and UV-vis techniques. The formation of α/β-Bi2O3 heterojunction can be proven by TEM, UV-vis diffuse reflectance spectra, and PL spectra results. The band gap energies of α-Bi2O3, β-Bi2O3, and α/β-Bi2O3 measured by UV-vis diffuse reflectance spectra were estimated to be about 2.9, 2.48, and 2.7 eV, respectively. The PL spectra of α/β-Bi2O3 heterojunction showed higher efficiency of charge separation and transfer across the α–β phase junction than those of α-Bi2O3 and β-Bi2O3, leading to the enhancement of photocatalytic activity. The synthesized α/β-Bi2O3 heterojunction can degrade 86% of rhodamin B (RhB) after 180 min under visible-light irradiation, better than those of pure α-Bi2O3 (24%, 180 min) and pure β-Bi2O3 (60%, 180 min). Consequently, α/β-Bi2O3 heterojunction is a promising photocatalyst, which can be easily prepared by SCS and post-treatment of NaOH solution.

Direct synthesis of vanadium oxide nanopowders by the combustion approach

In the paper, VO2 and V2O3 nanopowders were prepared via one-step solution combustion synthesis method. The properties of products can be tunable by adjusting the combustion parameters, such as fuel type, fuel-to-oxidizer ratio and atmosphere. Detailed combustion reaction mechanisms have been discussed. When glycine as fuel, the average particle size of VO2 product is 40 nm. When citric acid and glycine as the mixture fuels, the VO2 product with the average particle size of 20 nm show typical temperature-driven semiconductor to metal transition. The V2O3 product with the average size of 70 nm could be synthesized in an inert atmosphere.

Active and Stable Methane Oxidation Nano-Catalyst with Highly-Ionized Palladium Species Prepared by Solution Combustion Synthesis

We report on the synthesis and testing of active and stable nano-catalysts for methane oxidation. The nano-catalyst was palladium/ceria supported on alumina prepared via a one-step solution-combustion synthesis (SCS) method. As confirmed by X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HTEM), SCS preparative methodology resulted in segregating both Pd and Ce on the surface of the Al2O3 support. Furthermore, HTEM showed that bigger Pd particles (5 nm and more) were surrounded by CeO2, resembling a core shell structure, while smaller Pd particles (1 nm and less) were not associated with CeO2. The intimate Pd-CeO2 attachment resulted in insertion of Pd ions into the ceria lattice, and associated with the reduction of Ce4+ into Ce3+ ions; consequently, the formation of oxygen vacancies. XPS showed also that Pd had three oxidation states corresponding to Pd0, Pd2+ due to PdO, and highly ionized Pd ions (Pd(2+x)+) which might originate from the insertion of Pd ions into the ceria lattice. The formation of intrinsic Ce3+ ions, highly ionized (Pd2+ species inserted into the lattice of CeO2) Pd ions (Pd(2+x)+) and oxygen vacancies is suggested to play a major role in the unique catalytic activity. The results indicated that the Pd-SCS nano-catalysts were exceptionally more active and stable than conventional catalysts. Under similar reaction conditions, the methane combustion rate over the SCS catalyst was ~18 times greater than that of conventional catalysts. Full methane conversions over the SCS catalysts occurred at around 400 °C but were not shown at all with conventional catalysts. In addition, contrary to the conventional catalysts, the SCS catalysts exhibited superior activity with no sign of deactivation in the temperature range between ~400 and 800 °C.

One-Step Solution Combustion Synthesis of Cobalt Nanopowder in Air Atmosphere: The Fuel Effect.

In this paper, we report a new modified solution combustion synthesis technique for one-step production of metallic Co nanoparticles. The main unique feature of our approach is the use of microwave-assisted foam preparation. Also, the effect of different types of fuels (urea, citric acid, glycine, and hexamethylenetetramine) on the combustion process and characteristics of resultant solid products were investigated. It was shown that the combination of microwave-assisted foam and hexamethylenetetramine as a fuel allows us to produce metallic Co nanoparticles with the broad size distribution (∼5-40 nm), high coercivity (370 Oe), and high value of saturation magnetization (137 emu/g) by the one-step solution combustion synthesis under normal air atmosphere without any post reduction.

Bi5O7NO3 and Ag/Bi5O7NO3 composites: one-step solution combustion synthesis, characterization and photocatalytic properties

In the present study, Bi5O7NO3 and Ag/Bi5O7NO3 composites, as novel efficient photocatalysts, were synthesized via a one-step solution combustion synthesis (SCS) using bismuth nitrate (Bi(NO3)3·5H2O) as an oxidant, tartaric acid (C4H6O6) as a fuel, and silver nitrate (AgNO3) as an Ag source.