Microwave-Assisted Synthesis of Perovskite SrSnO3 Nanocrystals in Ionic Liquids for Photocatalytic Applications

Eco-Friendly Mechanochemical Synthesis of Bifunctional Metal Oxide Electrocatalysts for Zn-Air Batteries

The development of green and environmentally friendly synthesis methods of electrocatalysts is a crucial aspect in decarbonizing energy generation. In this study, eco-friendly mechanochemical synthesis of perovskite metal oxide-carbon black composites is proposed using different conditions and additives such as KOH. Furthermore, the optimization of ball milling conditions, including time and rotational speed, is studied. The mechanochemical synthesis in solid-state conditions without additives produces electrocatalysts that exhibit the highest bifunctional electrochemical activity towards both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Moreover, this synthesis demonstrates a lower Environmental Impact Factor (E-factor), indicating its greener nature, and due to its simplicity, it has a great potential for scalability. The obtained bifunctional electrocatalysts have been tested in a rechargeable zinc-air battery (ZAB) for 22 h with similar performance compared to the commercial catalyst (Pt/C) at significantly lower cost. These promising findings are attributed to the enhanced interaction between the perovskite metal oxide and carbon material and the improved dispersion of the perovskite metal oxide on the carbon materials.

Enhancing Optical and Thermal Stability of Blue-Emitting Perovskite Nanocrystals through Surface Passivation with Sulfonate or Sulfonic Acid Ligands

This study aims to enhance the optical and thermal properties of cesium-based perovskite nanocrystals (NCs) through surface passivation with organic sulfonate (or sulfonic acid) ligands. Four different phenylated ligands, including sodium β-styrenesulfonate (SbSS), sodium benzenesulfonate (SBS), sodium p-toluenesulfonate (SPTS), and 4-dodecylbenzenesulfonic acid (DBSA), were employed to modify blue-emitting CsPbBr1.5Cl1.5 perovskite NCs, resulting in improved size uniformity and surface functionalization. Transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the successful anchoring of sulfonate or sulfonic acid ligands on the surface of perovskite NCs. Moreover, the photoluminescence quantum yield increased from 32% of the original perovskite NCs to 63% of the SPTS-modified ones due to effective surface passivation. Time-resolved photoluminescence decay measurements revealed extended PL lifetimes for ligand-modified NCs, indicative of reduced nonradiative recombination. Thermal stability studies demonstrated that the SPTS-modified NCs retained nearly 80% of the initial PL intensity when heated at 60 °C for 10 min, surpassing the performance of the original NCs. These findings emphasize the optical and thermal stability enhancement of cesium-based perovskite NCs through surface passivation with suitable sulfonate ligands.

Evolution of the structure of MSnO3 (M = Ba, Sr) perovskites during hydrothermal synthesis and their photocatalytic activity

The synthesis of barium and strontium stannates in the process of decomposition of hydrothermally obtained precursors has been investigated. It was found that endothermic weight loss during the synthesis of barium stannate occurs in two stages, whereas during the synthesis of strontium stannate it occurs in one stage. From the summary of the results of thermogravimetric analysis, X-ray diffraction, and Mössbauer spectroscopy, the composition and local structure of X-ray amorphous phases are proposed. It is shown that the improvement of the crystal structure of the perovskite phases of MSnO3 (M = Ba, Sr) and the symmetry of the local environment of 119Sn continues up to high temperatures (1250-1500 °C) and is associated with the elimination of defects in the anion sublattice. The photocatalytic activity of hydrothermal phases MSn(OH)6 and their thermolysis products has been studied and was found not to be directly related to the specific surface area of the photocatalysts. The degradation of rhodamine B (RhB) occurs during the "dark" stages of catalysis due to the interaction of the dye with reactive oxygen species (mainly singlet oxygen). At the first stage, the decomposition of the RhB photochromic system is observed, whereas at the final stage of bleaching the dye is deethylated.

Modified BET theory for actual surfaces: implementation of surface curvature

The Brauner-Emmett-Teller (BET) theory was originally based on adsorbing surfaces of zero curvature. The theory is elaborated to include a curvature parameter. The theory has been developed for mono-size dense particles (spherical or rod-like) and porous materials with a sharp pore size distribution (spherical or cylindrical pores). Validation was performed considering 62 relevant published results. It is shown that for porous materials with cylindrical pores (15 cases), while the average error in the calculation of the specific surface area using the original BET theory is ca. 46%, that from the modified theory is ca. 11%. For porous materials with spherical pores (20 cases), an average error of 58% (BET theory) is reduced to 15%. To apply the new theory to dense materials, in addition to the probe-gas adsorption isotherm, skeletal density is needed. For meso-porous materials, the curvature parameter is calculated using the BJH theory.

Ag nanoparticle-decorated chitosan/SrSnO3 nanocomposite for ultrafast elimination of antibiotic linezolid and methylene blue

Effective design of ultrafast new-generation photocatalysts is a challenging task that requires highly dedicated efforts. This research focused on the development and design of ultrafast smart ternary photocatalysts containing SrSnO₃ nanostructures in conjugation with chitosan (CTSN) and silver (Ag) nanoparticles by a very simple and straightforward methodology. Modern analytical tools such as FESEM, TEM, XRD, XPS, FTIR, and UV-Vis spectroscopy were employed to characterize the synthesized nanostructures. XRD and XPS analysis confirmed the successful creation of ternary organization among the Ag, CTSN, and SrSnO₃. The TEM images clearly confirmed that CTSN possessed overlapping micron-sized sheets with a layered morphology, whereas the undoped SrSnO₃ particles exhibited spherical and elongated shapes and particle sizes ranging from 20 to 80 nm. These particles were produced in high density with homogeneously distributed Ag nanoparticles (4-15 nm). The bandgap energy (E_g) for bare SrSnO₃, CTSN/SrSnO₃, and Ag@CTSN/SrSnO₃ nanocomposites was found to be 4.0, 3.94, and 3.7 eV, respectively. The photocatalytic efficiencies of all newly created photocatalysts were evaluated by considering an antibiotic linezolid drug and methylene blue (MB) dye molecule as target analytes. Among all investigated samples, the Ag@CTSN/SrSnO₃ photocatalyst was found to be highly superior, with ultrafast removal of the linezolid drug at 96.02% within 25 min and almost total removal of the MB dye in just 12 min under UV light irradiation. The Ag@CTSN/SrSnO₃ photocatalyst exhibited removal rate that was 3.36 times faster than that of bare SrSnO₃. The present report delivers a highly promising, extremely efficient, and very simple, straightforward treatment methodology for the effective destruction of lethal and notorious pollutants, enabling the appropriate management of current environmental concerns.

Potential Application of Perovskite Structure for Water Treatment: Effects of Band Gap, Band Edges, and Lifetime of Charge Carrier for Photocatalysis

Perovskite structures have attracted scientific interest as a promising alternative for water treatment due to their unique structural, high oxidation activity, electronic stability, and optical properties. In addition, the photocatalytic activity of perovskite structures is higher than that of many transition metal compounds. A critical property that determines the high-performance photocatalytic and optical properties is the band gap, lifetime of carrier charge, and band edges relative to the redox potential. Thus, the synthesis/processing and study of the effect on the band gap, lifetime of carrier charge, and band edges relative to the redox potential in the development of high-performance photocatalysts for water treatment are critical. This review presents the basic physical principles of optical band gaps, their band gap tunability, potentials, and limitations in the applications for the water treatment. Furthermore, it reports recent advances in the synthesis process and comparatively examines the band gap effect in the photocatalytic response. In addition to the synthesis, the physical mechanisms associated with the change in the band gap have been discussed. Finally, the conclusions of this review, along with the current challenges of perovskites for photocatalysis, are presented.

Tuning of Structural and Magnetic Properties of SrSnO3 Nanorods in Fabrication of Blocking Layers for Enhanced Performance of Dye-Sensitized Solar Cells

Perovskite-based SrSnO₃ nanostructures doped with indium are prepared via a facile chemical precipitation method. Prepared nanostructures are used to assemble the dye-sensitized solar cells (DSSCs), and their photovoltaic response and electrochemical impedance spectra are measured. The synthesized samples are subjected to structural, morphological, optical, and magnetic properties. The X-ray diffraction pattern confirms the single-phase orthorhombic (Pbnm) perovskite structure. Local structural and phonon mode variations are examined by Raman spectra. Electron micrographs disclose the nanorods. The elements (Sr, Sn, O, and In) and the existence of oxygen vacancies are identified by X-ray photoelectron spectroscopy analysis. Surface area analysis demonstrates the higher surface area (11.8 m²/g) for SrSnO₃ nanostructures. Optical absorption spectra confirm the good optical behavior in the ultraviolet region. The multicolor emission affirms the presence of defects/vacancies present in the synthesized samples. The appearance of interesting ferromagnetic behavior in the prepared samples is due to the presence of F-center exchange interactions. Under the irradiation (1000 W/m²) of simulated sunlight, the DSSC fabricated by 3% In-doped SrSnO₃ exhibits the highest η of 5.68%. Hence, the blocking layers prepared with pure and indium-doped samples could be the potential candidates for DSSC applications.

Ionic Liquids and Deep Eutectics as a Transformative Platform for the Synthesis of Nanomaterials

Ionic liquids (ILs) are becoming a revolutionary synthesis medium for inorganic nanomaterials, permitting more efficient, safer and environmentally benign preparation of high quality products. A smart combination of ILs and...

Developing sustainable, high-performance perovskites in photocatalysis: design strategies and applications

Solar energy is attractive because it is free, renewable, abundant and sustainable. Photocatalysis is one of the feasible routes to utilize solar energy for the degradation of pollutants and the production of fuel. Perovskites and their derivatives have received substantial attention in both photocatalytic wastewater treatment and energy production because of their highly tailorable structural and physicochemical properties. This review illustrates the basic principles of photocatalytic reactions and the application of these principles to the design of robust and sustainable perovskite photocatalysts. It details the structures of the perovskites and the physics and chemistry behind photocatalytic reactions and describes the advantages and limitations of popular strategies for the design of photoactive perovskites. This is followed by examples of how these strategies are applied to enhance the photocatalytic efficiency of oxide, halide and oxyhalide perovskites, with a focus on materials with potential for practical application, that is, not containing scarce or toxic elements. It is expected that this overview of the development of photocatalysts and deeper understanding of photocatalytic principles will accelerate the exploitation of efficient perovskite photocatalysts and bring about effective solutions to the energy and environmental crisis.

SrSnO3-Assembled MWCNT Heterojunctions for Superior Hydrogen Production under Visible Light

A one-step sol-gel method for SrSnO3 nanoparticle synthesis and the incorporation of multi-walled carbon nanotubes (MWCNTs) to produce a SrSnO3@MWCNT photocatalyst is presented. The incorporation of MWCNTs results in enhancement of structural, optical, and optoelectrical properties of SrSnO3. The optimized 3.0% addition of MWCNTs results in light absorption enhancement and a reduction of the band gap from 3.68 to 2.85 eV. Upon application of the photocatalyst in the photocatalytic hydrogen production reaction, SrSnO3@MWCNT-3.0% yields 4200 μmol g-1 of H2 in just 9 h with the use of 1.6 g L-1 of the photocatalyst. SrSnO3@MWCNT exhibits remarkable chemical and photocatalytic stability upon regeneration. Enhanced photocatalytic ability is attributed to improved surface properties and charge-carrier recombination suppression induced by the MWCNT addition. This study highlights the remarkable improvements in chemical and physical properties of semiconductors with MWCNT incorporation.

Facile Way of Making Hydrothermally Synthesized Crystalline SrSnO3 Perovskite Nanorods Suitable for Blue LEDs and Spintronic Applications

Mn doping in SrSnO₃ perovskite material via hydrothermal process under subcritical conditions is reported for the very first time. The present article aims to carry this perovskite suitable for blue light-emitting diodes (LEDs) and spintronic applications. The influence of various Mn doping percentages on structural, morphological, compositional, optical, photoluminescent, and magnetic properties of SrSnO₃ is demonstrated. The perovskite material is grown in an orthorhombic crystal structure having a space symmetry of Pnma along with point group of mmm as determined from the Rietveld refinement. Doping is an excellent way to modify the properties of wide-band-gap perovskite nanostructures. Incorporation of Mn is the result of exact substitution. Morphological studies indicate formation of rodlike structures with thickness in nanoscale dimensions (180-280 nm), and the thickness is a function of doping concentration. The higher doping concentration resulted in enhanced growth of the nanorods. Selected area electron diffraction (SAED) results showed the single-crystal nature of the nanorods. Thermogravimetric analysis (TGA) confirmed the high stability of the material at elevated temperatures. Also, the doped perovskite material is transparent in the visible light, active in the ultraviolet region having a band gap of ∼2.78 eV, and is tuned up to 2.25 eV as the Mn doping concentration reaches 10%. The transfer of excitonic energy from the host material to the dopant Mn²⁺ ion leads to the formation of spin-forbidden [⁴T₁-⁶A₁] emission. Later on, photoluminescence study indicates an enhancement in luminescence behavior of Mn doped perovskite nanostructures. The Commission Internationale de l'éclairage (CIE) diagram drawn to find the color coordinates of the nanorods determines their suitability for blue LEDs. In addition, Mn doping results the conversion of diamagnetic SrSnO₃ into a ferromagnetic material, making the nanorods suitable for spintronic applications.

Novel fluorescent nano-sensor based on amino-functionalization of Eu3+:SrSnO3 for copper ion detection in food and real drink water samples

Lanthanide-doped nanoparticles exhibit unique optical properties and have been widely utilized for different sensing applications. Herein, the Eu3+:SrSnO3@APTS nanosensor was synthesized and its optical properties were analyzed using UV-Vis and photoluminescence spectroscopy. The TEM images of the synthesized nanophosphor Eu3+:SrSnO3@APTS exhibited peanut-like morphology, composed of two or more spherical nanoparticles with an average diameter ∼33 nm. Effects of environmental pH values and doping concentrations as well as amino functionalization on the structure of Eu3+:SrSnO3 were investigated. The as-synthesized optical nanosensor was used for determination of copper ions based on a fluorescence quenching approach. Red emission with a long lifetime was obtained in the case of the 0.06 mol Eu3+:SrSnO3@APTS sample. Under the optimal experimental conditions, a Stern-Volmer plot exhibited a good linearity for copper ions over the concentration (0.00-10.8) × 10-11 mol L-1 with a correlation efficient of 0.996 and a limit of detection 3.4 × 10-12 mol L-1. The fluorescent sensor was dynamically quenched via a coulombic interaction mechanism between the Eu3+ (5L6) and Cu2+. The Eu3+:SrSnO3@APTS nanosensor with the optimal Eu3+ dopant concentration of 0.06 mol was applied for copper determination in food and real drink water samples with high recovery values. We believe that the developed nanosensor probe can also be used for the detection of other toxic compounds, with high selectivity and sensitivity.

A soft chemistry approach to the synthesis of single crystalline and highly pure (NH4)CoF3 for optical and magnetic investigations

A new ionothermal synthesis utilizing 1-alkyl-pyridinium hexafluorophosphates [C_xPy][PF₆] (x = 2, 4, 6) led to the formation of highly crystalline single-phase ammonium cobalt trifluoride, (NH₄)CoF₃. Although ammonium transition-metal fluorides have been extensively studied with respect to their structural and magnetic properties, multiple aspects remain unclear. For that reason, the obtained (NH₄)CoF₃ has been investigated over a broad temperature range by means of single-crystal and powder x-ray diffraction as well as magnetization and specific heat measurements. In addition, energy-dispersive x-ray and vibrational spectroscopy as well as thermal analysis measurements were undertaken. (NH₄)CoF₃ crystallizes in the cubic perovskite structure and undergoes a structural distortion to a tetragonal phase at 127.7 K, which also is observable in the magnetic susceptibility measurements, which has not been observed before. A second magnetic phase transition occurring at 116.9 K is of second-order character. The bifurcation of the susceptibility curves indicates a canted antiferromagnetic ordering. At 2.5 K, susceptibility measurements point to a third phase change for (NH₄)CoF₃.

Synthesis and Dissolution of Metal Oxides in Ionic liquids and Deep Eutectic Solvents

Ionic liquids (ILs) and deep eutectic solvents (DESs) have proven to be suitable solvents and reactants for low-temperature reactions. To date, several attempts were made to apply this promising class of materials to metal oxide chemistry, which, conventionally, is performed at high temperatures. This review gives an overview about the scientific approaches of the synthesis as well as the dissolution of metal oxides in ILs and DESs. A wide range of metal oxides along with numerous ILs and DESs are covered by this research. With ILs and DESs being involved, many metal oxide phases as well as different particle morphologies were obtained by means of relatively simple reactions paths. By the development of acidic task-specific ILs and DESs, even difficultly soluble metal oxides were dissolved and, hence, made accessible for downstream chemistry. Especially the role of ILs in these reactions is in the focus of discussion.

Perovskite synthesis, properties and their related biochemical and industrial application

The perovskite structure is shown to be the single most versatile ceramic host. Inorganic perovskite type oxides are attractive compounds for varied applications due to its large number of compounds, they exhibit both physical and biochemical characteristics and their Nano-formulation have been utilized as catalysts in many reaction due to their sensitivity, unique long-term stability and anti-interference ability. Some perovskites materials are very hopeful applicants for the improvement of effective anodic catalysts performance. Depending Perovskite-phase metal oxides distinct variety of properties they became useful for various applications they are newly used in electrochemical sensing of alcohols, glucose, hydrogen peroxide, gases, and neurotransmitters. Perovskite organometallic halide showed efficient essential properties for photovoltaic solar cells. This review presents a full coverage of the structure, progress of perovskites and their related applications. Stress is focused particularly to different methods of perovskites properties and there related application.

New Developments in Material Preparation Using a Combination of Ionic Liquids and Microwave Irradiation

During recent years, synthetic methods combining microwaves and ionic liquids became accepted as a promising methodology for various materials preparations because of their high efficiency and low energy consumption. Ionic liquids with high polarity are heated rapidly, volumetrically and simultaneously under microwave irradiation. Hence, combination of microwave irradiation as a heating source with ionic liquids with various roles (e.g., solvent, additive, template or reactant) opened a completely new technique in the last twenty years for nanomaterials and polymers preparation for applications in various materials science fields including polymer science. This review summarizes recent developments of some common materials syntheses using microwave-assisted ionic liquid method with a focus on inorganic nanomaterials, polymers, carbon-derived composites and biomass-based composites. After that, the mechanisms involved in microwave-assisted ionic-liquid (MAIL) are discussed briefly. This review also highlights the role of ionic liquids in the reaction and crucial issues that should be addressed in future research involving this synthesis technique.

CsPbBr3 and CH3NH3PbBr3 promote visible-light photo-reactivity

Inorganic and organic lead halide perovskite materials attract great interest in the scientific community because of their potential for low-cost, high efficiency solar cells. In this report we add a new property of these materials, namely their photochemical activity in the visible light range. Both inorganic (CsPbBr3) and organic (CH3NH3PbBr3-MAPbBr3) perovskite thin films were demonstrated to promote photo-dissociation of adsorbed ethyl chloride (EC), employing 532 nm pulsed laser irradiation under ultra-high vacuum (UHV) conditions. From the post-irradiation temperature programmed desorption (TPD) analysis, the yield of photoproduct formation was found to be up to two orders of magnitude higher than for UV light-excited EC molecules on metallic and oxide surfaces. Photo-reactivity on top of the CsPbBr3 surface is almost an order of magnitude more efficient than on the CH3NH3PbBr3 surface, apparently due to the lower density of defect and surface states. A direct correlation was found between electron-induced luminescence and photoluminescence intensities and the photoreactivity cross-sections. We conclude that both the intense luminescence and the well-known photovoltaic properties associated with these halide perovskite materials are consistent with the efficiency of photo-reactivity in the visible range, reported here for the first time.