Chloride Precursors Research Articles

Highly Effective Proton-Conduction Matrix-Mixed Membrane Derived from an -SO3H Functionalized Polyamide

Developing a low-cost and effective proton-conductive electrolyte to meet the requirements of the large-scale manufacturing of proton exchange membrane (PEM) fuel cells is of great significance in progressing towards the upcoming “hydrogen economy” society. Herein, utilizing the one-pot acylation polymeric combination of acyl chloride and amine precursors, a polyamide with in-built -SO3H moieties (PA-PhSO3H) was facilely synthesized. Characterization shows that it possesses a porous feature and a high stability at the practical operating conditions of PEM fuel cells. Investigations of electrochemical impedance spectroscopy (EIS) measurements revealed that the fabricated PA-PhSO3H displays a proton conductivity of up to 8.85 × 10−2 S·cm−1 at 353 K under 98% relative humidity (RH), which is more than two orders of magnitude higher than that of its -SO3H-free analogue, PA-Ph (6.30 × 10−4 S·cm−1), under the same conditions. Therefore, matrix-mixed membranes were fabricated by mixing with polyacrylonitrile (PAN) in different ratios, and the EIS analyses revealed that its proton conductivity can reach up to 4.90 × 10−2 S·cm−1 at 353 K and a 98% relative humidity (RH) when the weight ratio of PA-PhSO3H:PAN is 3:1 (labeled as PA-PhSO3H-PAN (3:1)), the value of which is even comparable with those of commercial-available electrolytes being used in PEM fuel cells. Additionally, continuous tests showed that PA-PhSO3H-PAN (3:1) possesses a long-life reusability. This work demonstrates, using the simple acylation reaction with the sulfonated module as precursor, that low-cost and highly effective proton-conductive electrolytes for PEM fuel cells can be facilely achieved.

Laser-scribed conductive, photoactive transition metal oxide on soft elastomers for Janus on-skin electronics and soft actuators.

Laser-assisted fabrication of conductive materials on flexible substrates has attracted intense interests because of its simplicity, easy customization, and broad applications. However, it remains challenging to achieve laser scribing of conductive materials on tissue-like soft elastomers, which can serve as the basis to construct bioelectronics and soft actuators. Here, we report laser scribing of metallic conductive, photoactive transition metal oxide (molybdenum dioxide) on soft elastomers, coated with molybdenum chloride precursors, under ambient conditions. Laser-scribed molybdenum dioxide (LSM) exhibits high electrical conductivity, biocompatibility, chemical stability, and compatibility with magnetic resonance imaging. In addition, LSM can be made on various substrates (polyimide, glass, and hair), showing high generality. Furthermore, LSM-based Janus on-skin electronics are developed to record information from human skin, human breath, and environments. Taking advantage of its outstanding photothermal effect, LSM-based soft actuators are developed to build light-driven reconfigurable three-dimensional architectures, reshapable airflow sensors, and smart robotic worms with bioelectronic sensors.

Over 24% efficient MA-free CsxFA1−xPbX3 perovskite solar cells

<h2>Summary</h2> Methylammonium (MA)-free perovskites such as Cs_xFA_1−xPbX₃ (CsFA) show excellent thermal stability, favoring their use in perovskite solar cells (PSCs). However, the power conversion efficiency (PCE) of CsFA lags behind that of MA-containing formulations due to the difficulty in controlling the film morphology. Herein, we report innovative morphology engineering using solution deposition of a mixture of CsBr, PbI₂, and PbCl₂ followed by vacuum evaporation of formamidinium iodide (FAI) to fabricate CsFA films. The introduction of a chloride precursor leads to larger grain sizes, forming a high-quality CsFA film under annealing. This enables the realization of robust CsFA-based PSCs with the highest reported PCE up to 24.1% (certified 23.9%) for 0.1 cm² and 22.8% for 1 cm² devices. Moreover, the unencapsulated evaporation device shows excellent stability with negligible efficiency decline after 20,000 h of storage in dry air or 1,000 h of exposure to 50% humidity, which is much better than the device prepared using the solution procedure.

PREPARATION AND PROPERTIES OF NOVEL BIOCOMPATIBLE PECTIN/SILICA CALCIUM PHOSPHATE HYBRIDS

The development of bioactive polysaccharide-based hybrid materials is necessary for finding new alternatives in the field of biomaterials. As a bioactive water-soluble polysaccharide, pectin was used in this study to prepare reinforced silica gel monoliths through the sol-gel method. In-situ mineralization of calcium phosphate was achieved using calcium chloride and phosphate precursors. The properties of the pectin/silica/calcium phosphate hybrid were examined using FTIR, XRD and SEM/EDX techniques. Based on the results of the tests on kidney (Vero) cell lines, the pectin/silica/calcium phosphate hybrid demonstrated very mild cytotoxicity. In addition, the cytotoxicity of different hybrid concentrations was assessed with an MTT test, and the results demonstrated that their non-cytotoxicity for the concentrations investigated.

Role of cobalt precursors in the synthesis of Co3O4 hierarchical nanostructures toward the development of cobalt‐based functional electrocatalysts for bifunctional water splitting in alkaline and acidic media

AbstractThe precursors have significant influence on the catalytic activity of nonprecious electrocatalysts for effective water splitting. Herein, we report active electrocatalysts based on cobalt oxide (Co3O4) hierarchical nanostructures derived from four different precursors of cobalt (acetate, nitrate, chloride, and sulfate salts) using the low‐temperature aqueous chemical growth method. It has been found that the effect of precursor on the morphology of nanostructured material depends on the synthetic method. The Co3O4 nanostructures exhibited cubic phase derived from these four precursors. The Co3O4 nanostructures obtained from chloride precursor have demonstrated improved oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) compared to other precursors due relatively higher content of Co3O4 nanostructures at the surface of material. An overpotential of 400 mV versus reversible hydrogen electrode (RHE) at 10 mA cm−2 was observed for HER. The Co3O4 nanostructures derived from the chloride precursor have shown favorable reaction kinetics via 34 mV dec−1 value of the Tafel slope for HER reaction. The Co3O4 nanostructures derived from chloride precursor have also shown an excellent HER durability for 15 hr in alkaline media. Furthermore, the OER functional characterization was carried out onto Co3O4 nanostructures derived from chloride precursor exhibited 220 mV overpotential at 10 mA cm−2 and Tafel slope of 56 mV dec−1. Importantly, the reason behind the favorable catalytic activity of Co3O4 nanostructures derived from chloride precursor was linked to one order of magnitude smaller charge transfer resistance and higher amount of Co3O4 content at the surface of nanostructures than the Co3O4 nanostructures derived from other precursors. The performance of Co3O4 nanostructures derived from chloride precursor via the wet chemical method suggests that cobalt chloride precursor could be of great interest for the development of efficient, stable, nonprecious, and environmentally friendly electrocatalysts for the chemical energy conversion and storage devices.

Importance of Halide Ions in the Stabilization of Hybrid Sn-Based Coatings for Lithium Electrodes.

The properties of hybrid Sn-based artificial solid electrolyte interphase (SEI) layers in protecting Li-metal electrodes toward surface instabilities were investigated via a combined experimental and theoretical approach. The performance of coating layers can be coherently explained based on the nature of the coating species. Notably, when starting from a chloride precursor, the hybrid coating layer is formed by an intimate mixture of Li7Sn2 and LiCl: the first ensures a high bulk ionic conductivity, while the second forms an external layer allowing a fast surface diffusion of Li+ to avoid dendrite growth, a low surface tension to guarantee the thermodynamic stability of the protective layer, and a negative underneath plating energy (UPE) to promote lithium plating at the interface between the Li metal and the coating layer. The synergy between the two components and, in particular, the crucial role of LiCl in the promotion of such an underneath plating mechanism are shown to be the key properties to improve the performance of artificial SEI layers.

Photocatalytic efficiency of graphene/nickel oxide nanocomposites towards the degradation of anionic and cationic dye molecules under visible light

Simplified synthesis of nickel oxide nanorods (NiO NRs) and graphene/NiO nanocomposites (Grn/NiO NCs) was achieved using a chemical reduction approach of Grn and nickel chloride precursors. The crystalline nature of the prepared NiO NRs and Grn/NiO NCs was investigated using X-ray diffraction analysis, and the surface morphology was examined using transmission electron microscope. We examined the phtocatalytic efficiency of Grn/NiO NCs against anionic and cationic dye molecules. The Grn/NiO NCs showed 100% photocatalytic activity for methylene blue (MB) and methyl orange (MO) dye molecules within 90 and 120 min, respectively. The presence of Grn sheets has enhance the photocatalytic activity of NCs under visible light irradiation by reducing the recombination of excited electrons in the conduction band (CB) with holes in the valence band (VB) when Grn/NiO NCs reacted with dyes. We have developed efficient visible light functionalized Grn/NiO NCs photocatalysts for practical environmental applications using simple and cost-effective approach for large-scale manufacturing.

Optimisation of processing conditions during CVD growth of 2D WS2 films from a chloride precursor

Monolayer tungsten disulphide (WS2) is a direct band gap semiconductor which holds promise for a wide range of optoelectronic applications. The large-area growth of WS2 has previously been successfully achieved using a W(CO)6 precursor, however, this is flammable and a potent source of carbon monoxide (CO) upon decomposition. To address this issue, we have developed a process for the wafer-scale growth of monolayer WS2 from a tungsten hexachloride (WCl6) precursor in a commercial cold-wall CVD reactor. In comparison to W(CO)6, WCl6 is less toxic and less reactive and so lends itself better to the large-scale CVD growth of 2D layers. We demonstrate that a post-growth H2S anneal can lead to a dramatic improvement in the optical quality of our films as confirmed by photoluminescence (PL) and Raman measurements. Optimised films exhibit PL exciton emission peaks with full width at half maximum of 51 ± 2 meV, comparable to other state-of-the-art methods. We demonstrate that our WS2 films can be readily transferred from the sapphire growth substrate to a Si/SiO2 target substrate with no detectable degradation in quality using a polystyrene support layer. Our approach represents a promising step towards the industrial-scale fabrication of p-n junctions, photodetectors and transistors based on monolayer WS2.

Iron(ii) complexes supported by pyrazolyl-substituted cyclopentadienyl ligands: synthesis and reactivity

The preparation of bis(pyrazolyl)cyclopentadienyl iron complexes is described. Isopropyl substitution promotes solubility of the iron chloride complex that serves as a precursor to several derivatives through ligand exchange. Modification of the cyclopentadienyl substituent to replace a pyrazolyl unit with a phenyl group favors formation of a substituted ferrocene complex.

Fabrication of highly-conductive porous capacitor electrodes by the insertion of Cu-nanoparticles into N-doped flocculated carbon catalysts

In carbon-based electric double-layer capacitors (EDLC), an ideal electrode should have convenient mass transport, ensuring rich porosity and rapid electron transfer, guaranteeing the electrode bulk's high conductivity. In this study, ultrafine Cu nanoparticles inserted carbon flocculation is formed on carbon cloth using polydopamine and cupric chloride precursors via pyrolysis and electrochemical oxidation reaction. As a result, the obtained electrode has a large surface area of 55.5 m2g−1 and high conductivity of 48.7 S/mm, which shows excellent charge storage capability with high specific capacitance of 3546 mF cm−2 at a current density of 1 mA cm−2. Moreover, when the as-prepared electrode is used as electrodes in symmetric EDLC, it can provide a high energy density of 23 mWh cm−3 with a power density of 179 mW cm−3, making it as a promising carbon electrode for practical EDLCs.

Laser In-Situ synthesis of metallic cobalt decorated porous graphene for flexible In-Plane microsupercapacitors

Transition metal nanoparticles-graphene nanocomposites incorporate the advantages of graphene and metal nanoparticles, which arouse extensive attention. Here, we design a novel, facile and versatile method for in-situ synthesis of laser-induced porous graphene (LIG) decorated with cobalt particles (Co). The LIG/Co nanocomposites are fabricated through one-step laser direct scribing on a customized film composed of polyimide (PI) powder, polyvinyl alcohol (PVA), and cobalt chloride (CoCl2·6H2O) precursors. Benefiting from the unique properties of Co nanoparticles embedded LIG, the obtained optimal in-plane micro-supercapacitors (IMSC) based on LIG/Co-1.5 possesses an excellent areal capacitance of 110.11 mF cm−2 and a superior energy density of 9.79 μWh cm−2, which are about 79 times that of pure LIG-based IMSCs. Simultaneously, the LIG/Co-1.5 MSCs also present good cycling stability, remarkable modular integration capability, and outstanding mechanical flexibility, showing potential for practical applications. Additionally, the density functional theory (DFT) calculations indicate that the decorating of cobalt particles elevates electron transfer. Moreover, the interaction between electrolyte and electrodes is also improved with the introduction of cobalt particles. Therefore, this strategy offers a new avenue for facile and large-scale manufacturing of various metallic atoms in-situ decorating in porous graphene.

CO2 hydrogenation on CeO2@Cu catalyst synthesized via a solution auto-combustion method

Cu-based catalysts had been widely used in CO2 hydrogenation process for their excellent performance and high selectivity. Micron-sized Cu powder obtained by ball milling exhibited poor CO2 activity for its large particle size and small specific surface area, limited its catalytic application. In this work, micron Cu powder was modified with CeO2 species synthesized from different cerium precursor salts via a solution auto-combustion method to investigate CO2 hydrogenation activity. This work revealed that CeO2 species formed from cerium acetate precursor salt achieved excellent CO2 performance (1.64 mol/gcat.h at 400 °C), which was 3.8 times and 6000 times higher than that from cerium nitrate salt or cerium chloride salt, respectively. Interestingly, a thick dense CeO2 shell would be formed on micron Cu generated from cerium(III) chloride precursor salt, which inhibited CuOx reduction and had the opposite effect for RWGS reaction. In addition, the CuOx species in CeO2@Cu synthesized from cerium chloride salt resulted in the CH4 selectivity. The enhancement performance of the CeO2@Cu prepared from cerium acetate salt and cerium nitrate salt could be attributed to the oxygen defects formed around the Cu-Ox-Ce interface area and metallic Cu in the RWGS reaction. Cerium precursor salts enhanced the structural integrity of CeO2@Cu and played a vital role in RWGS reaction. These results will support a new direction for exploring micron Cu powder in Cu-based catalysts for CO2 utilization.

Ultrafast Response (&lt;1 µs) Perovskite Ultraviolet Photodetector via Ball‐Milling Pretreated Single‐Source Vapor Deposition

AbstractBenefiting from the rapid development on chloride incorporated perovskite materials, nowadays, novel device fabricating techniques have sparked a new vision of ultraviolet photodetectors (UVPDs), which is moving toward higher precision, lower energy consumption, and greater miniaturization. Nevertheless, the natural poor solubility of chloride precursors for perovskites has limited their processability for achieving high‐performance self‐driven photovoltaic‐type UVPDs. Herein, a ball‐milling pretreated single‐source vapor deposition strategy is presented, which can facilely fabricate a pure‐phase CsPbCl3 perovskite film with supermicrometer crystal size and no grain boundaries in the vertical direction. Based on this excellent quality UV harvesting perovskite layer, an optimized self‐driven visible‐blind UVPD exhibits outstanding detection properties, including a superior peak responsivity of 118 mA W−1, a maximum specific detectivity of 6.62 × 1012 Jones, and a wide linear dynamic range of 136 dB, coupled with &gt;1000 h operational durability in air ambient. Most notably, a recorded ultrafast rise/fall response time of 120/820 ns is realized as the fastest responsive perovskite UVPDs to date. In addition, this CsPbCl3 UVPD offers adequate visible‐transparency (&gt;50% average visible transmittance) for a glazing integration by using a transparent back electrode, providing a promising pathway to realize a transparent sensor system for future smart window applications.

Atom probe tomography investigation of 3D nanoscale compositional variations in CVD TiAlN nanolamella coatings

The cubic (Ti1−xAlx)Ny (TiAlN) phase with a nanolamella structure, synthesized via low pressure chemical vapour deposition (LPCVD), has been widely used in wear-resistant coatings during the latest years. The nanolamella structured TiAlN coatings contain periodic and epitaxially grown Ti-rich [denoted as Ti(Al)N] and Al-rich [denoted as Al(Ti)N] lamellae. However, the chemical compositions of these nano-structures have not been fully revealed. In this study, the microstructure of the nanolamella TiAlN coating was studied using scanning and transmission electron microscopy (SEM and TEM), and the chemical content was investigated using atom probe tomography (APT) that provides three-dimensional composition data with good accuracy and a spatial resolution down to the nanometer scale. It was found that over- and under-stoichiometries of N exist for the Ti(Al)N and the Al(Ti)N lamellae, respectively. According to the previous simulation results, such over- and under-stoichiometries are due to metal (Al and Ti) and N vacancies, respectively. The Al(Ti)N lamellae have a chemical formula of (Ti0.12Al0.88)N0.90, and have 10% N vacancies. The Ti(Al)N lamellae have a chemical formula of (Ti0.70Al0.30)0.97N, and have 3% metal (Al and Ti) vacancies. In addition to the nanolamella structure, compositional variations on a scale of a few nm were found in both types of lamellae. In the Ti-richest volumes, the composition corresponds to (Ti0.72Al0.28)0.88N so a maximum of 12% of metal vacancies exists. In the Al-richest volumes, the composition corresponds to (Ti0.07Al0.93)N0.64 so a maximum of 36% N vacancies exists. In addition, a small amount of Cl (around 0.1 at.%) was found in the coating, which could originate from the incomplete dissociation of chloride precursors during the CVD surface reaction.

Electrochemical Synthesis of Yttrium Aluminum Garnet Nanostructures in the Presence of Cationic Surfactant: CTAB

In this research, pure Yttrium Aluminum Garnet (YAG, Y3Al5O12) nanostructures were synthesized through a two-step process by using chloride precursors in a solution of water–ethanol electrolyte with specific ratio. Also, the effect of cationic surfactant CTAB, on the size and the morphology of the prepared nanostructures were investigated. For the synthesis of YAG, a layer of hydroxide film was deposited on the surface of cathode via cathodic electrodeposition method and then, it was transformed to the final oxide product in the course of a thermal operation. X-Ray Diffraction (XRD) analysis was used for characterization of phase and crystal structure of prepared materials and also Fourier Transform Infra-Red spectroscopy (FTIR) was used for characterization of absorption bonds. Thermal behavior of deposited hydroxide during the thermal operation was studied by Differential Thermal Analysis and Thermal Gravimetric Analysis (DTA-TGA) technique. The morphology and particle size of obtained powder was determined by Scanning Electron Microscopy (SEM). The results of our studies showed that the cathodic electrodeposition method is a practical and very efficient method for preparation of YAG nanostructures and addition of a cationic surfactant like CTAB into the electrolyte during the electrochemical deposition can lead to the formation of smaller particles and also has an impressive effect on the homogeneity and narrower particles size distribution.

Growth mechanism and electrical properties of tungsten films deposited by plasma-enhanced atomic layer deposition with chloride and metal organic precursors

We compared the growth characteristics and film properties of tungsten (W) thin films prepared by atomic layer deposition (ALD) using two newly synthesized precursors, tungsten pentachloride (WCl5) and ethylcyclopentadienyltungsten(V) tricarbonyl hydride (HEtCpW(CO)3), with Ar/H2 plasma as the reactant. The purpose of this study was to evaluate the suitability of these precursors for W thin films used in interconnect technology. The growth characteristics and film properties were significantly affected by the ligands of the precursors. The chemical compositional analysis results showed that high-purity thin films were obtained using the WCl5 precursor, compared to the films obtained using the HEtCpW(CO)3 precursor, which were relatively high in carbon content and oxygen impurities. The W thin films obtained from the WCl5 precursor showed superior electrical properties compared to those of the HEtCpW(CO)3 precursor, which were related to the crystallinity and film density in addition to the impurities. These results provide profitable information regarding the selection of a pertinent precursor for the device fabrication.

Exploring the influence of nickel precursors on constructing efficient Ni-based CO2 methanation catalysts assisted with in-situ technologies

In this work, a series of Ni-based CO2 methanation catalysts were prepared with different nickel salt precursors. The Ni-AA catalyst with nickel acetylacetonate precursor displayed the highest activity among these catalysts. The in-situ diffused reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS) and the online-tandem thermogravimetric mass spectrometry (TG-MS) were performed to investigate the intermediates of the catalyst calcination process. The superior performance of the Ni-AA catalyst could be derived from its special coordinating anion. Furthermore, the rapid deactivation of the Ni-S catalyst with nickel sulfate precursor was attributed to the generation of the Ni3S2 after reduction pretreatment. As for the Ni-Cl catalyst with nickel chloride precursor, its negligible activity could be owing to poisoning effect of the Cl− by the coverage of the catalyst surface. Therefore, the significant role of the metal salt precursor should be preferentially considered when designing the Ni-based catalysts and even other metal based heterogeneous catalysts.

Near UV luminescent Cs2NaBi0.75Sb0.25Cl6 perovskite colloidal nanocrystals with high stability

Near UV highly luminescent colloidal Cs2NaBiCl6 nanocrystals (NCs) were synthesized by a simple low-cost ligand-assisted reprecipitation method. In our strategy, metal chloride precursors were added to the mixture of anti-solvent and ligand at room-temperature. The obtained Cs2NaBiCl6 NCs exhibited a bright blue emission with significantly improved photoluminescence quantum yield (PLQY) of 39.05%. The optical properties and stability were greatly enhanced by doping Sb where Cs2NaBi0.75Sb0.25Cl6 showed a high PLQY of 46.57%, and both the powder and the colloidal solution exhibited superior stability.

Phase evolution, powder morphology and photoluminescence exploration of borohydride derived red-emitting Eu3+-doped ZnO nanophosphors

Deep red-emitting Eu3+-doped ZnO nanostructured materials were successfully prepared considering three different zinc-based precursor salts such as acetate, chloride and nitrate using sodium borohydride. XRD results confirmed the presence of ZnO at 800 °C for all samples. However, the nucleation of impurity phases such as EuBO3 and Eu(BO2)3 were significantly evolved and partly crystalline in nature while using nitrate precursor. When the samples were prepared by acetate and chloride precursors, the nucleation of impurity phases were not properly crystallized. The FTIR analysis confirmed the presence of metal-oxygen bond (M-O), triangular borate (BO3), tetrahedral borate (BO4) and hydroxyl (O–H/B–OH) groups, and thus it helps to form ZnO along with impurity phases. Flower-like morphology along with polyhedral particles was observed for acetate-based sample. In addition, polyhedral and elongated/elliptical shaped particles were found in nitrate and chloride precursor based samples. The Raman spectra suggested the presence of defects such as oxygen vacancy, zinc related defects, and their complexes in all the samples. Emission spectra for all samples exhibit a broad red emission at 613 nm, which corresponds to the electric dipole 5D0→7F2 transition. However, a splitting shoulder peak was significantly observed in the 5D0→7F2 transition for the sample prepared by nitrate precursor, and it was attributed to the existence of impurity phases. Moreover, the impurity phases were not evolved for the sample prepared by chloride and nitrate precursor, and thus the shoulder peak was not considerably noticeable. The presence of impurity phases in nitrate-based samples does not hamper but moderately enhanced the photoluminescence characteristics. The luminescence decay curve was well fitted with the bi-exponential function, and it suggested that the dopant ions have located in two different environments. The quantum yield of acetate-based sample was found to be 3.56%. Further, the results of asymmetric ratio, CIE coordinates and colour purity suggested that the samples can be used in red-emitting indoor lighting application.

Carbon Coating on Silicon for High-Performance Anode in Lithium-Ion Batteries

Silicon has attracted tremendous research interest as the next-generation anode material for lithium-ion batteries (LIBs) due to its approximately 10-fold higher capacity comparing to the graphite anode that is currently dominating the LIB market. Nevertheless, a critical drawback of silicon material is the dramatic volume change (>300%) during the lithiation and delithiation processes, which is a devastating destabilization factor for the silicon anode in battery cycling. Carbon coatings can serve as rigid framework to accommodate the volume change of silicon, to increase the conductivity of the silicon materials, and to protect the silicon surface from undesired side reactions. Here, we report two types of conductive carbon coatings on silicon materials through i) graphitization of a π-π stacking precursor poly(1-pyrenemethylmethacrylate) on SiO surface to encapsulate the SiO at a mild temperature, and ii) pyrolysis of polyvinylidene chloride precursor on silicon nanoparticle surface with stoichiometric ratio of sacrificial H and Cl elements that facilitate complete carbonization of the precursor. In addition, extended two‐phase transformation of carbon‐coated Si nanoparticles during electrochemical processes is examined.