Mixed Precursor Research Articles

Optimization of process parameters for preparing AlN nanopowders by combining carbon-containing droplet combustion and carbothermal reduction methods

In this research, AlN nano-powders were prepared by combining carbon-containing droplet combustion (CCDC) and carbothermal reduction (CR) methods. Firstly, Al2O3+C mixed precursor was synthesized by the CCDC method, and then AlN nano-powder was obtained by the carbothermal reduction of this CCDC precursor. The effects of urea and glucose contents, ignition temperature, and combustion atmosphere on precursors and AlN powders were studied in detail. The results showed that with the molar ratio of urea to aluminum nitrate (U/A) of 3, the atomic ratio of carbon to aluminum (C/Al) of 6, and the ignition temperature at 800 °C under air atmosphere, the prepared precursor was composed of hollow and spherical structure particles exhibiting rough and porous surface morphology with high specific surface area (SSA) (41.4 m2/g). AlN nano-powders obtained by the carbothermal reduction of this precursor were found to be consisted of fine particles with the size of 20–30 nm with high SSA of 39.9 m2/g.

Laser solid-phase synthesis of graphene shell-encapsulated high-entropy alloy nanoparticles

Rapid synthesis of high-entropy alloy nanoparticles (HEA NPs) offers new opportunities to develop functional materials in widespread applications. Although some methods have successfully produced HEA NPs, these methods generally require rigorous conditions such as high pressure, high temperature, restricted atmosphere, and limited substrates, which impede practical viability. In this work, we report laser solid-phase synthesis of CrMnFeCoNi nanoparticles by laser irradiation of mixed metal precursors on a laser-induced graphene (LIG) support with a 3D porous structure. The CrMnFeCoNi nanoparticles are embraced by several graphene layers, forming graphene shell-encapsulated HEA nanoparticles. The mechanisms of the laser solid-phase synthesis of HEA NPs on LIG supports are investigated through theoretical simulation and experimental observations, in consideration of mixed metal precursor adsorption, thermal decomposition, reduction through electrons from laser-induced thermionic emission, and liquid beads splitting. The production rate reaches up to 30 g/h under the current laser setup. The laser-synthesized graphene shell-encapsulated CrMnFeCoNi NPs loaded on LIG-coated carbon paper are used directly as 3D binder-free integrated electrodes and exhibited excellent electrocatalytic activity towards oxygen evolution reaction with an overpotential of 293 mV at the current density of 10 mA/cm2 and exceptional stability over 428 h in alkaline media, outperforming the commercial RuO2 catalyst and the relevant catalysts reported by other methods. This work also demonstrates the versatility of this technique through the successful synthesis of CrMnFeCoNi oxide, sulfide, and phosphide nanoparticles.

Manufacturing of heavy tungsten alloys from nano-sized metal oxides via simultaneous reduction-sintering powder treatments

Heavy tungsten alloys are of great importance in the engineering and mining industries as well as the military and medical applications because of their stability at high temperatures, high strength and dense structures. The present study develops a novel technology for the production of heavy tungsten alloys via thermal treatment of nano-sized metal oxides based on simultaneous reduction and sintering processes. Heavy tungsten alloy (95W-3Ni-2Fe) was produced from the reduction of mixed nano-sized metal oxides precursor in H2 at 1000 o C followed by sintering at 1350–1450 o C for 30–90 min. The reduced and sintered samples were characterized by XRD to follow up the crystallinity, total porosity measurement was used to find out the densification properties, the grain structure and morphology were examined by RLM and SEM attached with EDAX. Micro-hardness tester was also used to investigate the influence of sintering conditions on the grain densification. A fundamental study on the kinetics of reduction of mixed nano-sized metal oxides precursor was performed by isothermal and non-isothermal techniques. Both results from isothermal and non-isothermal tests were used to calculate the activation energy which was correlated with macro- and micro-structures to predict the corresponding reduction mechanism. However, the influence of sintering temperature and time on the crystallinity of the produced phases, grain structure, morphology, total porosity, pore-size distribution, bulk and apparent densities, and the hardness of sintered compacts was extensively investigated. The results revealed that the presence of NiO and/or Fe2O3 in the mixed metal oxides precursor was very important to ease the reducibility of WO3 as the metallic phases of Ni and/or Fe act as a catalyst for the reduction of WO3. The rate of reduction proceeds faster in the following order: NiO > Fe2O3 > mixed oxide > WO3. In non-isothermal experiments, it was found that the heating rate has a considerable effect on the reduction of precursor, i.e., the lower the heating rate, the higher the degree of reduction. It might be reported that the use of nano-sized metal oxides particles in the fabrication of heavy tungsten alloys greatly affects the main properties of the produced alloy. With the increase in sintering time, larger sizes of dense grains were developed, and the matrix became denser as a result of sintering and re-crystallization effects. The higher the sintering time, the higher the grain densification and the less pores formed in the matrix. On the other hand, with the increase in the sintering temperature, the grain boundaries were well defined in which the grains were composed of tungsten metal and surrounded by inter-metallics. The higher the temperature, the higher the XRD peak intensities of metallic tungsten and intermetallics as a result of sintering and re-crystallization.

One‐Step Aerosol Synthesis of Thiocyanate Passivated Hybrid Perovskite Microcrystals: Impact of (Pseudo‐)Halide Additives on Crystallization and Access to a Novel Binary Model

AbstractHybrid Perovskite materials have gone through an astonishing development due to their unique optoelectronic behavior, leading to the creation of a wide range of synthetic strategies. As the materials’ surface is found to play a crucial role with respect to the properties, e.g. hydration, stability and carrier mobilities, considerable efforts have been made to optimize the surface through various approaches. Especially the passivation of the perovskite surface attracted a lot of attention in this field, often resulting in more complex, multi‐step synthetic processes. In this study, a simple one‐step aerosol‐assisted synthetic approach is presented to obtain thiocyanate (SCN) passivated single‐crystal MAPbBr3 microcrystals. To elucidate the role of the additive in the crystallization process, mixed (pseudo‐)halide precursors are systematically investigated. The as processed, passivated microcrystals exhibit enhanced stability and charge carrier lifetimes. Additionally, a decrease in surface photovoltage, attributed to the presence of the SCN additive, is observed. Furthermore, the aerosol process is further developed resulting in a novel binary system containing MAPbBr3‐SCN perovskite microcrystals and Au nanostructures. This system serves as a promising model for further investigations into potential interactions between plasmonic and semiconducting materials, with initial results indicating prolonged charge carrier lifetimes.

How horizontal transport and turbulent mixing impact aerosol particle and precursor concentrations at a background site in the UAE

Abstract. The optical, physical, and chemical properties of aerosol particles have been previously studied in the United Arab Emirates (UAE), but there is still a gap in the knowledge of particle sources and in the horizontal and vertical transport of aerosol particles and their precursors in the area. To investigate how aerosol particle and SO2 concentrations at the surface responded to changes in horizontal and vertical transport, we used data from a 1-year measurement campaign at a background site where local sources of SO2 were expected to be minimal. The measurement campaign provided a combination of in situ measurements at the surface and the boundary layer evolution from vertical and horizontal wind profiles measured by a Doppler lidar. The diurnal structure of the boundary layer in the UAE was very similar from day to day, with a deep, well-mixed boundary layer during the day transitioning to a shallow nocturnal layer, with the maximum boundary layer height usually being reached around 14:00 local time. Both SO2 and nucleation-mode aerosol particle concentrations were elevated for surface winds coming from the east or western sectors. We attribute this to oil refineries located on the eastern and western coasts of the UAE. The concentrations of larger cloud condensation nuclei (CCN)-sized particles and their activation fraction did not show any clear dependence on wind direction, but the CCN number concentration showed some dependence on wind speed, with higher concentrations coinciding with the weakest surface winds. Peaks in SO2 concentrations were also observed despite low surface wind speeds and wind directions unfavourable for transport. However, winds aloft were much stronger, with wind speeds of 10 m s−1 at 1 km common at night and wind directions favourable for transport; surface-measured concentrations increased rapidly once these particular layers started to be entrained into the growing boundary layer, even if the surface wind direction was from a clean sector. These conditions also displayed higher nucleation-mode aerosol particle concentrations, i.e. new particle formation events occurring due to the increase in the gaseous precursor.

Methods of Producing Disordered Rocksalt Cathode Materials

Li-rich cation-disordered rocksalts (DRX) have attracted attention as a promising new class of Co-free Li-ion battery cathodes. Current synthesis and optimization routes of DRX materials often require the use of high-energy ball-milling, which creates inhomogeneous distributions and non-ideal particle morphologies. A new technique to synthesize DRX materials was developed at Materials Engineering Research Facility (MERF) by forming a mixed transition metal hydroxide precursor material through aqueous co-precipitation before calcining the precursor with a Li-source. Such a method enables a controllable and scalable route to synthesize DRX materials.

Excellent self-cleaning surface achieved through the synergistic effect of superhydrophilicity and photocatalysis of PVDF-TiO2-HAP coating

With the increasing demand for living environment, high-performance self-cleaning coatings have become an urgent need in the development of new building industry. Herein, a TiO2-HAP-PVDF self-cleaning coating was successfully developed using a facile precursor mixing method, where porous hydroxyapatite (HAP) was used to facilitate the adsorption of pollutants, TiO2 served as photocatalyst to decompose pollutants, and polyvinylidene fluoride (PVDF) served as adhesive to combine TiO2 with HAP. Owing to the synergistic effect of superhydrophilicity and photocatalysis, the TiO2-HAP-PVDF coating displays outstanding self-cleaning performance. Furthermore, the as-fabricated coating attached to aluminum veneer not only resists mechanical abrasion such as rainwater, sand flow and sandpaper, but also exhibits good stability in the extremely temperatures from -196 to 150 °C, as well as in strong acid and alkaline solutions, and even presents satisfactory performance after 8000 hours of outdoor service test. These merits open exciting possibilities for the industrial application of self-cleaning coating.

Stepwise Construction of Multimetallic Complexes Supported by Heteroditopic NHC/MIC Ligands

AbstractWe report the stepwise synthesis of a novel series of heterometallic gold(I)/palladium(II) complexes supported by heteroditopic imidazol‐2‐ylidene/triazol‐5‐ylidene ligands. All new compounds were characterized by means of 1H and 13C NMR spectroscopy, melting points, and elemental analyses. The versatility of the ligand platforms, additionally allows for the preparation of cationic chelate biscarbenic palladium(II) complexes through full deprotonation of the mixed azolium precursors. Characterization studies were completed by the determination of the molecular structures of some synthetic intermediates. The new biscarbenic palladium(II) complexes were tested as catalysts in the cross‐coupling of boronic acid to a variety of chloroarenes and the hydrosilylation of terminal alkynes. Both catalytic processes provide good to excellent yields under low catalyst loadings.

Rapid fabrication of binder free nickel cobalt oxide electrodes with dendritic nanostructure for electrochemical energy storage applications

A rapid and facile technique to synthesize nickel cobalt oxide electrodes by photothermal treatment of mixed organometallic precursor solution is reported. Using short and intense pulses of light from a xenon flash lamp, spray coated films are converted into porous nickel cobalt oxide electrodes with dendritic nanostructure. The electrode films fabricated in a few seconds show excellent energy storage properties as supercapacitor electrodes. Specific capacitance of up to 116 Fg−1 and capacitance retention of up to 75 % were observed in samples with low mass loading. Analysis of the cyclic voltammetry (CV) curves shows that capacitance is the dominating charge storage mechanism in these films. To study the effect of varying the mass loading in electrodes, double and triple layered electrodes were also studied. In films with high mass loading, the specific capacitance of the films decreased but areal capacitance continued to increase. A high areal capacitance of up to 243 mFcm−2 is observed in films with high mass loading. CV curve analysis of high mass loading electrodes further shows that in films with higher mass loading, the charge storage mechanism is a mix of capacitance and diffusion processes. The contribution of diffusion increased with increase in the mass loading of the electrodes. This study sheds light into the mechanism of charge storage in electrodes prepared by large-scale-amenable single step process of photonic curing which could be utilized to fabricate electrodes in industrial scale.

Catalytic Hydroconversion of Lauric Acid Over Poly(N-vinyl-2-pyrrolidone)-Coated Pd Nanoparticles on ZIF-8

A subclass of Metal-Organic Frameworks, Zeolitic Imidazole Frameworks-8 (ZIF-8) is known as an emerging material that has the characteristic of a large surface area, good thermal stability as well as a high porosity. Instead of having extraordinary properties, ZIF-8 consists of Lewis acid and Lewis base site on its Zn metals and 2-methylimidazole which are the important components for the catalyst. In this study, Pd-Poly(N-vinyl-2-pyrrolidone) coated on ZIF-8 (Pd-PVP@ZIF-8) was synthesized by mixed Pd-PVP solution and ZIF-8 precursors at room temperature. The Pd-PVP solution was varied from 10 to 50 ml to differentiate the Pd concentration in ZIF-8. As-synthesized 50 ml of Pd-PVP on ZIF-8 (50Pd-PVP@ZIF-8) showed catalytic activity in the conversion of 98.6% lauric acid to produce 78.2% of 1-dodecanol at optimum condition 320 °C for 6 h. The synergy between Pd-PVP as metal and ZIF-8 as metal support as well as high dispersion of Pd particles could enhance performance in the conversion of lauric acid. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Mixed biomass-derived multi-heteroatom doped carbon-decorated Mn3O4 for a high-performance asymmetric all solid-state supercapacitor

Recently, the development of non-conventional electrochemical energy storage technologies has attracted great attention. Herein, in accordance with green strategies for the producing renewable energy storage systems, eco-friendly electrode was successfully produced from mixed biomass precursors through carbonization and activation processes. Obtained electrode (MB-AC) as a negative and its composite (Mn3O4@MB-AC) as positive electrodes were exhibited excellent electrochemical performance with high specific capacitance of 716.49 Fg−1 at 0.75 Ag−1 and 848.21 Fg−1 at 1.0 Ag−1 respectively, in 3 M KOH electrolyte. Further, for the practical application, flexible asymmetric all-solid-state supercapacitor was made. Which offer high specific capacitance of 266.46 Fg−1 at 2 Ag−1, high energy density of 119.91 Wh kg−1 at a high-power density of 1800.08 W kg−1 within a voltage window of 1.8 V. These prominent electrochemical performances suggest that selected waste biomass materials derived carbon have considerable applications in the field of energy storage technologies.

A facile dual isolation and protection strategy for preparation of PtFe intermetallic compound in biomass-derived carbon with high activity and durability for pH-universal bifunctional electrocatalysts

A facile dual isolation and protection strategy is developed to prepare PtFe intermetallic electrocatalyst (PtFe–N–C@bioC) on porous biomass carbon (bioC) derived from peanut shell. In preparation, meso-tetraphenylporphyrine (H2TPP) together with platinum (II)-tetraphenylporphyrin (PtTPP) are in-situ fabricated on the porous peanut shell-derived bioC matrixes and then further absorbed Fe (III) tetraphenyl porphyrin (FeTPP) molecules through π−π interactions between PtTPP/H2TPP and FeTPP to form a mixed precursor of FeTPP/PtTPP/TPP-bioC. Upon pyrolysis of FeTPP/PtTPP/TPP-bioC, PtFe bimetallic-containing N-doped carbon formed on bioC (PtFe–N–C@bioC). The resultant PtFe–N–C@bioC showed excellent oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) activity across a wide pH range. In particular, under alkaline medium, PtFe–N–C@bioC shows the ORR performance with an onset potential (Eonset) of 0.989 V, a half-wave potential (E1/2) of 0.901 V and a limiting current density (JL) of −6.214 mA cm−2. Meanwhile, PtFe–N–C@bioC delivers an enhanced mass activity (1.197 A mg−1Pt), which is 13 times larger than commercial Pt/C. For HER, PtFe–N–C@bioC shows an impressive overpotential (η10) of 17 mV at a current density of 10 mA cm−2 under acidic medium. Further, it is applied to Zn-Air batteries with a power density performance of 98.7 mW cm−2 and good durability.

P507-modified magnetic porous carbon derived from metal-organic frameworks for efficient separation of zirconium(IV) and hafnium(IV)

Extractant-based solid phase extraction exhibit practical application potential for efficient separation of Zr(IV) and Hf(IV), where the key is to regulate the host–guest interaction between the guest extraction agents and the host matrices to obtain high performance. However, the current research on the host matrices of extraction agents is insufficient. Leveraging the tunability of metal–organic frameworks (MOFs), we successfully prepared a magnetic MOF-derived porous carbon (C(Zn/Co-ZIF)) with a high specific surface area and Co-Nx active sites as an excellent matrix. This was achieved by deliberately controlling the pore volume and microenvironment through a mixed precursor strategy and high-temperature pyrolysis method. Furthermore, as an excellent extractant for the separation of Zr(IV) and Hf(IV) in solvent extraction, 2-ethylhexyl phosphonic acid mono-(2-ethylhexyl) ester (P507) was carefully selected to modify C(Zn/Co-ZIF) to obtain C(Zn/Co-ZIF)@P507 by impregnation. Impressively, the maximum adsorption capacities of C(Zn/Co-ZIF)@P507 for Zr(IV) and Hf(IV) were up to be 0.58 and 0.39 mmol/g, respectively, while exhibiting excellent separation coefficient. Further mechanism studies indicated that the combination of high specific surface area and abundant Co-Nx active sites of C(Zn/Co-ZIF) leaded to strong interaction with P507, resulting in the excellent adsorption and separation performance of Zr(IV) and Hf(IV) based on the coordination between phosphinic groups of P507 and Zr(IV)/Hf(IV).

Practical liquid phase mixing-calcination synthesis of Nb5+ doped SrTiO3 nanoparticles with elevated photocatalysis

The mediocre photocatalytic activity and unpractical preparation methods of SrTiO3 have restricted its practical application as a photocatalyst. Herein, a practical liquid phase mixing-calcination method was designed to synthesize Nb5+ doped SrTiO3 (Nb-SrTiO3) with remarkably elevated photocatalytic activity. Nb-SrTiO3 nanoparticles were synthesized by mixing Sr(NO3)2, NbCl5 and tetrabutyl titanate in deionized water (DW), evaporating the solvent (DW) and calcining the evenly mixed precursors at 700 °C for 4 h. The as-synthesized Nb-SrTiO3 exhibited a photocatalytic activity 4.2 times that of SrTiO3 in the reduction of Cr(VI) under Xenon lamp irradiation. Moreover, Nb-SrTiO3 showed a rather good photocatalytic stability. Nb5+ doping can decrease the particle size and promote the photogenerated carrier separation and transfer of SrTiO3, thereby contributing to heightened photocatalytic activity of Nb-SrTiO3.

Improving electrochemical performance of Ni-rich layered cathode material with combining Co-enriched compositional gradient and radial microstructure

Ni-rich complex layered oxides LiNixMnyCozO2 (x > 0.85) with a combined Ni/Co concentration gradient and radially oriented elongated plate-like primary particles were synthesized with hydrothermal microwave-assisted treatment of an as-prepared mixed hydroxide precursor with aqueous solution of Co source and urea followed by a high temperature annealing with a Li source. The radial distribution of plate-like primary crystallites in microwave-treated materials was achieved through Co-enrichment at the surface, which likely triggered the surface-to-bulk growth of plate-like particles rather than isotropic octahedral crystallites. The Co-modified cathode materials demonstrate greatly improved cycling stability (capacity fade per cycle of 0.04 ± 0.01%) compared to unmodified Ni-rich NMCs (capacity fade per cycle of 0.13 ± 0.02%) with similar Ni concentration, as well as good rate capability (215, 210, 199, 189, 178 and 160 mAh/g at C/10, C/5, C/2, 1C, 2C, and 5C rates at 2.7–4.3V vs Li/Li+). Enhanced electrochemical performance is linked to the improved mechanical integrity, which was achieved through radial microstructure organization of the agglomerates triggered by Co concentration gradient, suppressing the intragranular crack formation.

Tricomponent direct co-assembly to nitrogen-doped, ordered mesoporous carbon@silica frameworks with enhanced nitrogen stability and multi-functionalities

Ordered mesoporous carbon@silica hybrid frameworks with high nitrogen content and good stabilities show great significance to improve their functionalities. Herein, we report novel nitrogen-doped (3.51 ∼ 4.62 wt%) and ordered mesoporous carbon@silica frameworks (N-OMC@SiO2) with reinforced nitrogen stability. The N-OMC@SiO2 were designed from tricomponent direct co-assembly between block copolymer template and mixed precursors containing urea and tetramethoxysilane without using additional solvent. The N-OMC@SiO2 have large BET surface areas (444.3 ∼ 674.9 m2/g), uniform mesoporous channels (5.8 ∼ 10.9 nm) with well-defined hexagonal symmetry, and stable carbon@silica “reinforced concrete” framework that can be transformed into carbon@silicon by controllable reduction. The nitrogen sites were firmly embedded into their frameworks via the formation of Si-N bonding. Thus, the resulted N-OMC@SiO2 exhibit multi-functionalities and enhanced recyclability in acid waste gas capture and gaseous sulfides catalytic utilization, better than many reported porous adsorbents and catalysts. This study may help develop stable and efficient N-OMCs nanocomposites for acidic gas selective removal.

Multifunctionally Reusing Waste Solder to Prepare Highly Efficient Sn-Pb Perovskite Solar Cells.

The preparation of perovskite components (PbI2 and SnI2) using waste materials is of great significance for the commercialization of perovskite solar cells (PSCs). However, this goal is difficult to achieve due to the purity of the recovered products and the easy oxidation of Sn2+. Here, a simple one-step synthetic process to convert waste Sn-Pb solder into SnI2/PbI2 and then applied as-prepared SnI2/PbI2 to PSCs for high additional value is adopted. During fabrication, Sn-Pb waste solder is also employed to serve as a reducing agent to reduce the Sn4+ in Sn-Pb mixed narrow perovskite precursor and hence remove the deep trap states in perovskite. The target PSCs achieved an efficiency of 21.04%, which is better than the efficiency of the device with commercial SnI2/PbI2 (20.10%). Meanwhile, the target PSC maintained an initial efficiency of 80% even after 800h under continuous illumination, which is significantly better than commercial devices. In addition, the method achieved a recovery rate of 90.12% for Sn-Pb waste solder, with a lab-grade purity (over 99.8%) for SnI2/PbI2, and the cost of perovskite active layer reduced to 39.81% through this recycling strategy through calculation.

Construction of n-n type homojunction band alignment of defective graphitic carbon nitrides derived from mixed precursors for superior photo-catalytic activity

Graphitic carbon nitride (C3N4) emerges as an exceptionally promising photocatalyst thanks to its favourable characteristics, such as being non-metallic, sourced from abundant raw materials, and possessing outstanding thermal, physical, and chemical stability. Defects-induced C3N4 plays a crucial role in enhancing photo-catalytic activity. In this study, the authors utilize the conventional sintering method to prepare g-C3N4 by employing mixed precursors, namely melamine and thiourea. The band alignment between n-n type C3N4 samples derived from these two different precursors was meticulously established. Four distinct compositions of C3N4 are obtained by varying the weight ratios of melamine and thiourea during the in-situ synthesis. Various analytical methods thoroughly investigate these samples' physical/photo-chemical properties. Among the various samples, MT-GCN-A, characterized by a higher melamine (1.0 g) and lower thiourea (0.25 g) weight ratio, demonstrated superior attributes. These include a high specific surface area (14.28 m2 g−1), pore size (23.57 nm), and lower band gap (2.85 eV) in comparison to the other samples. When utilized as a photocatalyst for degrading Congo red (CR) under UV and visible-light irradiation, MT-GCN-A exhibited enhanced performance compared to the diverse samples. These findings highlight that the thoughtful combination of melamine and thiourea in C3N4 facilitates efficient separation and transfer of photo-generated electron-hole pairs, thereby enhancing the photo-catalytic activity.

Effect of polymethyl methacrylate on in situ patterning of perovskite quantum dots by inkjet printing.

The preparation of perovskite quantum dots (PQDs) using an in situ inkjet printing method is beneficial for improving the problems of aggregation and photoluminescence (PL) quenching during long-term storage. However, the stability of PQDs prepared using this method is still not ideal, and the morphology of in situ-printed patterns needs to be optimized. To address these problems, this study introduced polymethyl methacrylate (PMMA) into the process of in situ inkjet printing of PQDs and explored the effect of PMMA on the in situ patterning effect of PQDs. The results showed that using a mixed precursor solution containing a small amount of PMMA as the printing ink can slow down the shrinkage process of ink droplets and improve the uniformity of film formation. As the printing substrate, PMMA provided a suitable high-viscosity environment for the in situ growth of PQDs. This could effectively suppress the coffee ring effect. In addition, the interaction between the C=O=C group in PMMA and metal ion Pb2+ in the CsPbBr3 precursor molecules was favourable to enhancing the density of PQDs. The prepared PMMA-coated CsPbBr3 quantum dots (QDs) pattern had high stability and could maintain at 90.08% PL intensity after 1 week of exposure to air.

Spin-coated CZTS films prepared by two different precursor mixing regimes, at room temperature and at 150 °C

In this paper, we examine the impact of the precursor's mixing temperature and mixing protocol on the crystal structure and morphological and optical properties of Cu2ZnSnS4 (CZTS) thin films. Four samples of CZTS thin films were synthesized with the sol-gel spin coating technique by previously mixing precursors at (a) 150 °C and (b) room temperature (RT), either (i) all at once or (ii) through sequential adding the individual chemicals 30 min apart. SEM-EDX, XRD, Raman and Visible spectroscopy analysis showed that sample 150°C-ST (chemicals mixed at the same time at 150 °C) fulfilled all the theoretical stoichiometric criteria (poor in Cu, rich in Zn) for the high-quality CZTS absorbers. The larger grain size (850 nm) and crystallite size (73.96 nm), lower strain (0.49×10−3) and band gap Eg=1.44eV which is closest to the Shockley–Queisser limit for single junction solar cells (1.34 eV).