Facile Low-temperature Synthesis Research Articles

Facile Low-Temperature synthesis of novel carbon nitrides for efficient conversion of carbon dioxide into Value-Added chemicals

The interest in using carbon nitrides (CN) for CO2 conversion has stimulated extensive research on CN synthesis. Herein, we report the synthesis of two novel CN materials using low-cost commercially available precursors at low temperatures in a short duration of time. Two CN materials, one derived from 5-amino tetrazole (named 4NZ-CN) and the other derived from 3, 5-diamino-1, 2, 4-triazole (named 3NZ-CN) precursors, are prepared by refluxing these precursors for 2 h at 100 °C. 4NZ-CN and 3NZ-CN catalysts show higher surface areas (55.80 and 52.00 m2 g-1) and more basic sites (10.05 and 5.65 mmol g−1) than the conventional graphitic carbon nitride (g-C3N4) derived from melamine, for which the corresponding values are 9.20 m2 g-1 and 0.62 mmol g−1, respectively. In addition, both CN exhibit a 3-fold higher catalytic activity for CO2 cycloaddition to epoxides than g-C3N4. The structure−activity relationship was ascertained using a combination of experimental and computational studies, and a catalytic mechanism was proposed. This work provides a facile strategy for the synthesis of novel CN materials at relatively low temperatures, and the developed catalysts show remarkable performance in the conversion of CO2 to value-added chemicals.

Cu2O@Au-CsPbI3 heterostructures for plasmon hot carrier transfer enhanced optoelectronics

Plasmon hot carrier devices have tremendous potential applications in broadband photovoltaics, photodetection, photocatalysis, and intelligent optoelectronics, as they have the ability to generate hot carriers with energy lower than the optical bandgap at Schottky junctions and broaden the spectral range. However, this is mostly challenged by the lack of effective methods for the separation, migration, and extraction of plasmon hot carrier. In this work, a Cu2O@Au-CsPbI3 heterostructure was fabricated using facile low-temperature solution synthesis and spin-coating technique. The proposed heterostructure benefits from the simultaneous transfer of plasmon hot holes to Cu2O and hot electrons to CsPbI3, as well as enhanced charge separation driven by the built-in electric field at the p-n heterojunction interface. The heterostructure realizes remarkably enhanced light absorption, reduces carrier recombination, and further improves conversion efficiency. It exhibits a wide spectrum response of ultraviolet-visible-near infrared and achieves enhanced photodetection performance. The results suggest that Cu2O@Au-CsPbI3 heterostructure is a promising candidate for optoelectronic devices based on the harvesting of plasmonic hot carriers.

Supramolecular assembly of blue and green halide perovskites with near-unity photoluminescence.

The metal-halide ionic octahedron is the optoelectronic unit for halide perovskites, and a crown ether-assisted supramolecular assembly approach can pack various ionic octahedra into tunable symmetries. In this work, we demonstrate near-unity photoluminescence quantum yield (PLQY) blue and green emission with the supramolecular assembly of hafnium (Hf) and zirconium (Zr) halide octahedral clusters. (18C6@K)2HfBr6 powders showed blue emission with a near-unity PLQY (96.2%), and green emission was also achieved with (18C6@K)2ZrCl4Br2 powders at a PLQY of 82.7%. These highly emissive powders feature facile low-temperature solution-based synthesis conditions and maintain high PLQY in solution-processable semiconductor inks under ambient conditions, and they were used in thin-film displays and emissive three-dimensional-printed architectures that exhibited high spatial resolution.

Pd-Enriched-Core/Pt-Enriched-Shell High-Entropy Alloys Nanoparticles with a Face-Centred Cubic Structure for C1 and C2 Alcohol Oxidation.

Recently, high-entropy alloy nanoparticles (HEA NPs) have aroused great interest globally with their unique electrochemical, catalytic, and mechanical properties, as well as diverse activity and multielement tunability for multi-step reactions. Herein, a facile low-temperature synthesis method at atmospheric pressure is employed to synthesize Pd-enriched-HEA-core and Pt-enriched-HEA-shell NPs with a single phase of face-centred cubic structure for promoting the oxidation of C1 and C2 alcohols. Interestingly, the lattice of both Pd-enriched-HEA-core and Pt-enriched-HEA-shell enlarge during the formation process of HEA, with tensile strains included in the core and shell of HEA. Strikingly, the as-made PdAgSn/PtBi HEA NPs show excellent electrocatalytic activity and durability for methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR). Especially, the specific (mass) activity of PdAgSn/PtBi HEA NPs for MOR is 4.7 mA/cm2 (2874 mA mg(Pd+Pt)-1), about 1.7 (5.9) and 1.5 (4.8) times higher than that of commercial Pd/C and Pt/C catalysts, respectively. Combined with high-entropy effect, Pt sites and Pd sites on the interface of the HEA act synergistically to facilitate the multi-step process towards EOR. This study offers a promising way to find a feasible route for scalable HEA manufacturing with promising applications.

Low-temperatures synthesis of CuS nanospheres as cathode material for magnesium second batteries

Rechargeable magnesium batteries (RMBs), as one of the most promising candidates for efficient energy storage devices with high energy, power density and high safety, have attracted increasing attention. However, searching for suitable cathode materials with fast diffusion kinetics and exploring their magnesium storage mechanisms remains a great challenge. CuS submicron spheres, made by a facile low-temperature synthesis strategy, were applied as the high-performance cathode for RMBs in this work, which can deliver a high specific capacity of 396 mAh g−1 at 20 mA g−1 and a remarkable rate capacity of 250 mAh g−1 at 1000 mA g−1. The excellent rate performance can be assigned to the nano needle-like particles on the surface of CuS submicron spheres, which can facilitate the diffusion kinetics of Mg2+. Further storage mechanism investigations illustrate that the CuS cathodes experience a two-step conversion reaction controlled by diffusion during the electrochemical reaction process. This work could make a contribution to the study of the enhancement of diffusion kinetics of Mg2+ and the reaction mechanism of RMBs.

Tailoring structure, nonlinear/linear optical, and dielectric properties of PVA/PVP film by spinel LiMn2O4 nanoparticles

LiMn2O4 (LMO) nanoparticles have received significant attention owing to their role in energy storage and power supply applications. Here, the facile low-temperature synthesis of new hybrid freestanding films incorporated with different LMO nanoparticle concentrations (0, 0.037, 0.37, and 3.7 wt.%) was preceded to tunable the optical and electrical properties of the PVA-PVP blend. The formation of the nanoparticles and polymeric nanocomposite (PNC) films was confirmed using various techniques, including HRTEM, SEM, FTIR, and XRD. The relationship between the optical and dielectric properties of the films with the bandgap was tuned using the doping ratio. Two models were used to estimate the precision of the optical transition bandgap. Our results revealed that the calculated extinction coefficient, Urbach energy, optical conductivity, and refractive index of PVA-PVP were enhanced. The nonlinear optical parameters, including the third-order susceptibility (χ(3)) and refractive index (n2), also improved with a reduction in the bandgap. In addition, a hybrid film with 3.7 wt.% LMO exhibited excellent optical shielding. However, the electrical properties of the PNC films are not only affected by the applied frequency but can also be tuned by the LMO ratio. The AC conductivity and dielectric constant of the hybrid/PNC films were enhanced by the addition of LMO, and the highest values were achieved for the semi-transparent PNC with 0.37 wt.% LMO. For the oblique film with 3.7 wt.% LMO, most nanoparticles cover the significant portions of the polymer surface, which decreases the electrical properties. The dominant mechanism in all PNC films is related to barrier hopping (CBH) and follows Jonscher's power (JP) performance. The investigated hybrid films are promising for environmental optoelectronics, photosensors, optical shielding, and Li+ ion-based battery devices.

Facile solid-state synthesis of tetragonal CuFe2O4 spinels with improved infrared radiation performance

Spinel materials are gradually becoming promising materials for high infrared emissivity owing to their unique crystal structure. However, the facile low-temperature solid-state synthesis of infrared radiation materials with superior emissivity remains a tremendous challenge. Herein, a general and simple approach for scalable synthesis of CuFe2O4 samples with spinel structure at low temperatures is smartly developed. The optimal experimental conditions for the infrared emissivity of CuFe2O4 are obtained by the detailed investigation into experimental parameters including calcination temperatures, heating rates, and the mass of polyvinyl pyrrolidone. Under the optimal experimental conditions, the infrared emission values of CuFe2O4 in the wavelength range of 3–5 μm can be as high as 0.986. More significantly, the work here will provide significant guidance for the efficient preparation of spinel materials with excellent infrared emissivity, especially at low temperatures.

PH-stimuli-responsive phosphors with controllable morphology and size by a facile low-temperature synthesis method

The pH-stimuli-responsive luminescent nanoparticles are promising for a wide range of applications because of responsive luminescence and excellent optical properties. Here we show a facile low-temperature synthesis of green-emitting Zn2SiO4:Mn2+ (ZSM) nanoparticles with regular shape, uniform size and good luminescent performance. The microstructure and micromorphology of ZSM are characterized by XRD and SEM. The photoluminescence (PL) spectra are collected and analyzed, which further demonstrated the successful doping of Mn2+ into the Zn2SiO4 lattice. In addition, we also study the possible mechanism by which the prepared ZSM have pH-stimulated responsive luminescence. The pH-stimuli-responsive luminescence also gives the ZSM the ability to encrypt information in a more secure manner and prevents information leakage.

Facile low-temperature synthesis of W-rich Cu1−xZnxWO4 nanoparticles and the electrochemical performance

This paper reports the facile low-temperature synthesis of Cu1−xZnxWO4 nanoparticles by varying the concentration of Zn using solid-state reaction method. The incorporation of various Zn concentrations can alter the valence band energy and enhance the structural, optical and electrochemical properties. The prepared nanoparticles have a triclinic crystal structure with minimum strain. The variation in zinc concentration is shown by the densely aggregated particles in the SEM image. These nanoparticles exhibit strong absorption in the visible region and the bandgap is found to increase with an increase in Zn concentration. The photocurrent density increases with an increase in the concentration of zinc and found to be a maximum of 8.5 µA cm−2 for x = 0.4 due to a lower bandgap of 2.65 eV. Finally, it is observed that an optimum zinc concentration promotes improved photocurrent generation.

A novel terbium doping effect on physical properties of lead sulfide nanostructures: A facile synthesis and characterization

Abstract

Facile low-temperature synthesis of nickel oxide by an internal combustion reaction for applications in electrochromic devices

Electrochromic nickel oxide ion storage anodes compatible to tungsten oxide as cathode layer are prepared by a combustion reaction with urea as fuel and nickel nitrate as oxidizer at temperatures not higher than 230 °C to stay well within the temperature range in which thermally sensitive intercalated tungsten oxide layers are still stable. The precursors for nickel oxide are well available materials and the preparation of the layers can be performed at low energy input by spin-coating onto the substrate and moderate heating on a hot-plate. Ethanol and acetone where used as solvents and reveal large differences in the resulting film morphologies, electric and electrochromic characteristics. Cyclic voltammetry measurements in contact to lithium perchlorate (LiClO4) in propylene carbonate show remarkable colouration efficiencies at 550 nm of 47 cm2 C−1 for NiO prepared from ethanol solution and 92 cm2 C−1 for NiO prepared from acetone solution, which are, to the best of our knowledge, among the highest reported values for Li+-intercalation into NiO prepared at moderate substrate temperature reported so far.Graphic abstract

Facile low-temperature solid-state synthesis of efficient blue-emitting Cs3Cu2I5 powder phosphors for solid-state lighting

The discovery of new environmentally friendly luminescent materials with high photoluminescence quantum yield and long-term stability is critical for future solid-state lighting and displays applications. Although lead halide perovskite materials with excellent optical properties have been extensively investigated in recent years because they hold tremendous promise in optoelectronic devices, the toxicity of lead and poor air-stability still hinder their commercial applications. Moreover, while substantial work has been done on three-dimensional (3D) perovskite halides, the zero-dimensional (0D) halide emitters with bright luminescence remain elusive. Herein we report a facile solid-state reaction method to prepare an efficient lead-free all-inorganic halide material with 0D structure, Cs3Cu2I5, with photoluminescence quantum yield up to 80%. Under ultraviolet excitation at 313 nm, the Cs3Cu2I5 powder phosphors show a strong blue photoluminescence emission with peak at 445 nm and CIE color coordinates of (0.1486, 0.0873). Notably, Cs3Cu2I5 exhibits good color stability at high temperatures and outstanding stability towards air exposure exceeding one month (30 days). These findings not only open up a door for the development of promising highly emissive low-dimensional halide materials for lighting and displays, but also offer a new scalable approach for the potential mass production of halide emitters.

Magnetic iron phosphide particles mediated peroxymonosulfate activation for highly efficient elimination of sulfonamide antibiotics

Transition metal phosphides (TMPs) have emerged as a promising catalyst in the environmental catalysis field due to the excellent catalytic property, high conductivity and long stability. Herein, spherical-coral-like iron phosphide (FexP) particles contained FeP orthorhombic crystals and Fe2P hexagonal crystals were innovatively constructed by a facile low-temperature phosphating synthesis strategy. This novel heterogeneous catalyst with unique morphology was firstly employed for peroxymonosulfate (PMS) activation to eliminate SDZ. It was turned out that FexP possessed favorable catalytic activity for activating PMS and could eliminate SDZ up to 98.2% within 24 min. Compared with Fe2O3 without further phosphatizationtreatment, the introduction of phosphorus in Fe2O3 significantly ameliorated the catalytic activity for the elimination of SDZ and the apparent rate constant (kobs) increased by 9.1 times. More importantly, the FexP particles exhibited magnetic property which is convenient for recycling use. This feature is very different from the previously reported TMPs catalytic materials. Besides, four types of reactive oxygen species (ROS) including sulfate radical (SO4−), hydroxyl radical (OH), singlet oxygen (1O2) and superoxide radical (O2−) were detected to play a key role in SDZ elimination by electron paramagnetic resonance (EPR) cooperated with radical quenching tests. This finding opened up an avenue for developing and utilizing TMPs catalytic materials in the environmental remediation.

Low-Temperature Solution Synthesis of Black Phosphorus from Red Phosphorus: Crystallization Mechanism and Lithium Ion Battery Applications.

As a thermodynamically stable semiconductor material, black phosphorus (BP) has potential application in the field of energy storage and conversion. The preparation of black phosphorus is still limited to the laboratory, which is far from adequate to meet the requirements of future industrial applications. Here, the gram-scale black phosphorus is synthesized in the ethylenediamine medium using a 120-200 °C low-temperature recyclable liquid phase method directly from red phosphorus. A crystallization mechanism from red to black phosphorus based on FTIR, XPS, and DFT calculations is proposed. Black phosphorus as the anode material for lithium ion batteries is superior in discharge specific capacity, rate capability, and cycling stability in comparison with red phosphorus. The facile low-temperature synthesis of BP by the ethylenediamine-assisted liquid phase process will facilitate the extended application of BP in the field of energy storage and conversion.

Facile low-temperature synthesis and application of La0.85Sr0.15Co0.85Fe0.15O3-δ as superior cathode for LT-SOFCs using C-TAB as surfactant

ABSTRACT Nanocomposite based on LSCF (La0.85Sr0.15Co0.85Fe0.15O3-δ) was prepared by a simple chemical precipitation method for application in low-temperature solid oxide fuel cells (LT-SOFC) as a cathode by using basic materials (Rare earth and Transition metal related compounds), sodium hydroxide [as precipitator material] and CTAB [as surfactant]. DTA/TGA of the precursor compound indicated the completion of reaction at about 300 °C. The formation of well-crystalline single-phase perovskite structure with rhombohedral geometry was revealed by the XRD and La-O bond is assigned in the sample revealed by FTIR. SEM analysis unveiled that the sample comprises spherical shaped and homogeneous with an average grain size of about 90 nm. EDAX reveals the elemental composition of the sample. Impedance measurements have been made in voltage −1.3 volts and the frequency range – 42 Hz to 5 KHz. Better conductivity value is attained that may make this system appropriate for application as cathode for Low-temperature solid oxide fuel cells (LT-SOFCs).

A facile low-temperature synthesis of nanosheets assembled PbS microflowers and their structural, morphological, optical, photoluminescence, dielectric and electrical studies

In current article we report a simple one pot synthesis of lead sulfide (PbS) microflowers (MFs) assembled with nanosheets at low temperature by chemical co-precipitation route. SEM study confirm the low dimension NFs morphology of final product. Furthermore, MFs were subjected to structural, vibrational, diffused reflectance, photoluminescence and impedance spectroscopy measurements. Structural and vibrational studies proved the development of single phase highly crystalline PbS MFs. The respective average crystallite size, lattice strain and dislocation density was ∼9.950 nm, 0.011 (1/nm2) and 0.003. Direct and indirect energy gaps were determined through Kubelka-Munk method ∼0.71 eV and 0.56 eV, respectively, which are superior than bulk (i.e. 0.41 eV). There is clear enrichment in energy gap of MFs which signify the existence of confinement effect. PL emission shows an intense violet emission bands at ∼386 nm and 407 nm. Dielectric constant, loss and ac electrical conductivity were studied at higher frequencies at different bias voltages and discussed. Obtained results presents a new insight on PbS for optoelectronic device applications.

Enhanced photocatalytic activity of CuS-ZnO rods towards degradation of pollutants under visible-light-driven nanostructured photocatalyst

A facile low temperature synthesis of ZnO rods and decoration of CdS and CuS on ZnO rods were synthesised via sonication assisted one-pot hydrothermal method. The synthesised samples were characterised by XRD, UV–visible DRS, XPS and FE-SEM. The photocatalytic degradation of methylene blue (MB) was studied. When CuS was loaded on ZnO rods, it showed higher degradation of MB of 98.2% and 90% by CdS-ZnO and 48% by ZnO nanorods at a reaction time of 210 min. The pH, photocatalyst dosage and initial dye concentration were kept same for all the three photocatalyst during the degradation.

A facile low-temperature synthesis of hierarchical porous Co3O4 micro/nano structures derived from ZIF-67 assisted by ammonium perchlorate

Sub-micro hierarchical porous Co3O4 dodecahedra with a large specific surface area (106.11 m2 g−1) were synthesized by the thermolysis of ZIF-67 at a low temperature of 268 °C assisted by ammonium perchlorate (AP).

Facile low-temperature one-step synthesis of pomelo peel biochar under air atmosphere and its adsorption behaviors for Ag(I) and Pb(II)

This study prepared a novel low-cost surface functionalized carbon adsorbent (PPC) from biomass waste (pomelo peel) through a facile low-temperature (250 °C) one-step method under regular air atmosphere. The adsorption performance and mechanism of the carbon material for Ag(I) and Pb(II) were investigated by a range of sorption experiments and characterizations including SEM, EDX, XRD and FTIR. Sorption experimental results suggested that PPC had high adsorption capacities of 137.4 and 88.7 mg/g for Ag(I) and Pb(II), respectively, with adsorbent dosage of 2 g/L at unadjusted solution pH and room temperature (23 ± 1 °C). The characterization results indicated high-efficiency removal of the heavy metals by PPC was attributed to the strong chemical adsorption involving that Ag(I) ions were reduced as metallic Ag particles by oxygenic functional groups and Pb(II) ions were precipitated as Pb5(PO4)3OH crystals by phosphorous functional groups on the carbon surfaces. This study provides the possibility of synthesis high-efficient adsorbent using economic and environmental-friendly approach with low energy consumption.

Low-Temperature Presynthesized Crystalline Tin Oxide for Efficient Flexible Perovskite Solar Cells and Modules.

Organic-inorganic metal halide perovskite solar cells (PSCs) have been emerging as one of the most promising next generation photovoltaic technologies with a breakthrough power conversion efficiency (PCE) over 22%. However, aiming for commercialization, it still encounters challenges for the large-scale module fabrication, especially for flexible devices which have attracted intensive attention recently. Low-temperature processed high-performance electron-transporting layers (ETLs) are still difficult. Herein, we present a facile low-temperature synthesis of crystalline SnO2 nanocrystals (NCs) as efficient ETLs for flexible PSCs including modules. Through thermal and UV-ozone treatments of the SnO2 ETLs, the electron transporting resistance of the ETLs and the charge recombination at the interface of ETL/perovskite were decreased. Thus, the hysteresis-free highly efficient rigid and flexible PSCs were obtained with PCEs of 19.20 and 16.47%, respectively. Finally, a 5 × 5 cm2 flexible PSC module with a PCE of 12.31% (12.22% for forward scan and 12.40% for reverse scan) was fabricated with the optimized perovskite/ETL interface. Thus, employing presynthesized SnO2 NCs to fabricate ETLs has showed promising for future manufacturing.