Physicochemical Characterization Techniques Research Articles

Metal–organic framework/sulfur‐doped graphene oxide nanocomposite for high efficiency electrochemical double‐layer capacitors

The use of highly porous electrode substances is very useful for high efficiency electrochemical double‐layer capacitors. Therefore, this work was presented an electrochemical nanocomposite material consisting of ZIF‐8 crystals deposited on sulfur‐doped graphene oxide nanosheets for supercapacitor applications. To confirm the synthesis of products, the preparation materials were examined by different physicochemical characterization techniques. The efficiency of the fabricated samples as supercapacitor electrode materials was probed by electrochemical analysis. The results show improvement in electrochemical capacitance, power, and energy densities of S‐doped‐GO/ZIF‐8 (SGZ) nanocomposite. The power density of 231 W/kg, the specific capacitance of 261 F/g, and the energy density of 13.4 W h/kg with cyclic stability of 102% following 1000 cycles for SGZ nanocomposite make it a good candidate for electrochemical applications.

Detoxification of Toxic Organic Dye by Heteroatom-Doped Fluorescent Carbon Dots Prepared by Green Hydrothermal Method Using Garcinia mangostana Extract

In this work, nitrogen- and oxygen-doped fluorescent carbon dots (NOFCDs) were prepared using a simple green hydrothermal carbonization technique. Aqueous ammonia and the plant extract of Garcinia mangostana were used as a source of nitrogen and carbon, respectively. The prepared NOFCDs were examined using a variety of microscopic and spectroscopic techniques for physicochemical characterization. Fluorescence and UV–visible spectroscopy measurements were used to analyze the NOFCDs’ excitation-dependent fluorescent emission and absorption nature. It is observed that fluorescence intensity was excited at 320 nm and the strongest emission peak absorbed at 405 nm. The HRTEM imaging revealed NOFCDs to be spherical in shape with particle size at 3.58 nm. Moreover, the amorphous nature of NOFCDs was verified by X-ray diffraction, Raman spectroscopy, and SAED pattern techniques. Through FTIR, XPS, and EDS investigations, the doping of nitrogen and oxygen over the surface of the NOFCDs was evaluated and validated. The presence of carboxylic, amine, hydroxyl, and carbonyl functional groups on NOFCDs’ surface was shown by XPS and FTIR investigations. By using NaBH4, the obtained NOFCDs were demonstrated to possess excellent catalytic activity in the detoxification of methylene blue. Overall, this study revealed that the NOFCDs synthesized from green sources could be a promising material for catalytic and environmental remediation applications.

Sustainable synthesis of vanadate/fluorapatite nano-crystallites from solid waste for enhanced photocatalysis and pollution removal

In this work, vanadate-fluorapatite, V2O5/Ca10(PO4)6F2, nanocrystals were successfully synthesized through a straightforward one-step co-precipitation method. This method was based on two toxic solid wastes, which are mainly generated as by-products during sulfuric acid manufacturing and in the phosphate industry. The two solid wastes were mainly based on phosphogypsum as a source of calcium and vanadium pentoxide as a source of vanadate. In comparison to numerous conventional methods for FAP synthesis, this innovative method is not laborious, not complex, cost-effective, and environmentally friendly, thanks to the recovery of toxic solid wastes. Furthermore, it consists of mixing various contents of anhydrous gypsum with phosphoric acid, vanadium pentoxide, and ammonium fluoride at one time and at room temperature with no further adjustment of the pH. Several physicochemical characterization techniques were used, including X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Ultraviolet-Visible Spectroscopy (UV-vis). Whereas SEM analysis of the crystals obtained showed a nanometer-scale fluorapatite crystallites was obtained. The obtained results offer exciting potential for applying the prepared nanomaterial in both photocatalysis and pollution removal. They hold great promise and are expected to generate significant interest in these fields.

Studies on Pectin-Tin(IV) Phosphate: A New Biopolymer Doped Hybrid Ion Exchanger, An Efficacious Ion Exchanger in Water Purification Process

Pectin doped tin(IV) phosphate was prepared as novel class of hybrid ion exchanger i.e. biopolymer based hybrid ion exchanger, which has been characterized by few physico-chemical characterization techniques such as FTIR analysis, SEM study, UV-vis spectrophotometry and elemental analysis. The characteristic parameters of novel ion exchange such as ion exchange capacity, concentration study, elution study, thermal stability, etc. were also reported. Adsorption study has been explored for few alkaline earths and some heavy or transition metal ions in several acidic media. Based on adsorption study, it has been found that the reported ion exchanger has shown enantioselectivity for cadmium(II) ions, being one among toxic metal ions. The antimicrobial activity of pectin based tin(IV) phosphate on few microorganisms has also been studied to prove the antimicrobial nature of the synthesized ionexchange material.

Peptide-functionalized graphene oxide quantum dots as colorectal cancer theranostics

Colorectal cancer (CRC) accounts for approximately 10% of all new cancer cases worldwide with significant morbidity and mortality. The current imaging techniques are lacking diagnostic precision while traditional chemotherapeutic strategies are limited by their adverse side effects and poor response in advanced stages. Targeted nanoparticles (NPs) can specifically bind to surface antigens on cancer cells and provide effective delivery of diagnostic and chemotherapeutic agent. Placenta-specific protein 1 (PLAC-1) is overexpressed in CRC and can be used as a target for detection and treatment of the disease. The aim of this work was to develop a targeted nanotheranostic agent for early diagnosis and inhibition of the malignant progression and metastasis of CRC. Graphene oxide quantum dots (QD) were covalently labeled with a peptide (GILGFVFTL) having high affinity to PLAC-1. The covalent coupling between the QD and the peptide was confirmed using a series of physicochemical and morphological characterization techniques. Confocal microscopy was used to evaluate the uptake of QD and QD-P in HCT-29, HT-116 and LS-180 CRC cell lines. Selective targeting of antigen PLAC-1 overexpressed on HT-29 and HCT-116 cells was measured by immunofluorescence. Cell proliferation, cell invasion and extent of PLAC-1 expression in CRC cells after treatment with QD and QD-P were determined. The prepared QD-P showed a significant increase in targeting and specific uptake in cells expressing the antigen PLAC-1 compared to non-functionalized QD. Treatment with QD-P also increased the cell cytotoxicity, reduced the invasiveness of HT-29 and HCT-116 cells by 38% and 62%, respectively, and downregulated the expression of PLAC-1 by 53% and 33%, respectively. These results highlight the potential use of QD-P as a theranostic agent for the detection and treatment of CRC cells expressing the antigen PLAC-1.

Adsorption of CO2 and N2 on bimetallic Mg-Al hydrotalcites and Z-13X zeolites under high pressure and moderate temperatures

The adsorption of carbon dioxide on a commercial hydrotalcite (HT) was investigated using gravimetric analysis at 473 K, 573 K and 673 K and pressures up to 10 bar. The CO2 adsorption performance of HT was correlated with a wide range of physicochemical characterisation techniques. For further understanding and comparative purposes, the same adsorption and characterisation measurements are reported for a commercial zeolite 13X (Z-13X). The HT exhibited higher adsorption capacities per unit mass of sorbent at relatively low pressures and per unit surface area over the whole range of pressures analysed, compared to zeolite 13X. However, HT showed adsorption-desorption isotherms with a hysteresis loop indicating a stronger binding energy. The HT also presented deactivation upon cycling (up to ∼ 10%, depending on conditions) suggesting the need for future studies focused on improvement of its regenerability. The same performance regarding hysteresis and deactivation was observed in the presence of N2. The CO2 adsorption isotherms of HT were successfully fitted to the Freundlich model. The values of heat of adsorption calculated -56 and -84 kJ mol−1 for the 1st and 5th cycle, are indicative of a chemisorption process. The data of this work provide information regarding fundamentals of CO2 adsorption of the materials that is useful in the design of realistic adsorption units in conventional and novel H2Carbon Dioxide Capture processes, especially in the sorption-enhanced H2 reaction process.

Sol‐gel route synthesis of high energy density Li [Li0.2Ni0.3Mn0.7] O2 cathode with controlled structure, morphology and enhanced electrochemical performance

AbstractThe desire for long driving range and low cost of electric vehicles necessitates the use of superior rechargeable lithium batteries. These batteries with enhanced energy density addresses the demand for cutting‐edge cathode materials which can deliver amplified voltage and capacity. Lithium‐rich manganese is one among such promising cathodes for lithium‐ion batteries. In this work, three different organic acids, including oxalic (OX), tartaric (TA) and ascorbic (AS) acids were used to synthesis Li [Li0.2Ni0.3Mn0.7] O2 (LNMO) materials with three unique microstructures. Physicochemical and electrochemical characterization techniques were used to investigate a range of properties. Electrochemical investigations demonstrated regulated morphology‐enhanced electronic conductivity, increased energy density and prolonged cycle behavior. Among the three samples, AS‐LNMO unveiled a capacity of 308.02 mhAg−1 nearing the value of theoretical capacity. Whereas, TA‐LNMO exhibited a remarkable stability even after 200 cycles with capacity retention of 99.3%. With specific discharge capacities of 308.02, 278, 252, 228 and 212 mAhg−1 at 0.1C, 0.2C, 0.5C, 1C and 2C respectively, AS‐LNMO exhibited superior rate capability. Collectively, this research offers valuable insights in using complexing agents which positively impacts the morphology and electrochemical performance of LNMOs in upcoming lithium‐ion batteries.

Unveiling the role of surface functional groups for the design of nickel manganese/reduced graphene oxide based composite electrode material for high performance asymmetric supercapacitor

Development of additive-free electrode material on conductive substrates is a cost-effective strategy and is essential for the fabrication of high-performance supercapacitor. Herein, the effect of transition metal ions on the preparation of bimetallic (Ni & Mn)/reduced graphene oxide (RGO) composites through multi-step electrodeposition technique was extensively analysed. Two different composites; nickel manganese oxide/RGO (NiMn-G/NF) and manganese nickel oxyhydroxide/RGO (MnNi-G/NF) were synthesized through step-wise electrodeposition technique. The NiMn-G/NF and MnNi-G/NF were prepared through interchanging the source of host transition metal ions (Ni and Mn). Various physicochemical characterization techniques confirmed that the crystal structure as well as the morphology and electrochemical performance of the composites were largely dependent on the host metal ions. The formation of surface functional groups may play a key role in the electrochemical performance of supercapacitors. The MnNi-G/NF electrode showed high specific capacitance of ~1525 F g−1 at 1.5 A g−1 current density compared to NiMn-G/NF (~1312.5 F g−1) and other synthesized electrode materials. An asymmetric supercapacitor (ASC) device was fabricated using MnNi-G/NF as positive and thermally-RGO as negative electrode materials. The fabricated device exhibited highest specific capacitance of ~173.3 F g−1 at 2 A g−1 current density and maximum energy density of ~54.1 Wh kg−1 and power density of 9 kW kg−1.

A Reachable Sodium-Oxygen Battery Based on Sodium Superoxide Chemistry

Sodium-oxygen (Na-O2) batteries offer a great potential to provide high energy density storage systems needed for small-sized and inexpensive electric vehicles owing to the abundance of sodium compared with lithium. Yet, their development is hindered by the low cycle life and poor energy efficiencies due to (i) the formation of singlet oxygen, resulting in parasitic reactions with the air cathode and the organic electrolyte, (ii) the formation of unstable SEI layers and dendrites associated with the metallic sodium anode, and (iii) lack of an active, stable cathode catalyst to reduce the overpotentials and improve the cycle stability.Here, we have developed a Na-O2 battery cell composed of a highly active cathode catalyst that works well in synergy with an ether-based ionic-liquid electrolyte with specific redox mediators to act as co-catalysts to reversibly form and decompose sodium superoxide (NaO2) via surface-mediated pathway at a low polarization gap of about 40 mV at a capacity of 1000 mAh/g. Different electrochemical and physicochemical characterization techniques, i.e., Raman spectroscopy, XRD, XPS, DEMS, SEM, and TEM were used to understand the cell chemistry. Moreover, a chemically synthesized Na anode protection layer implemented in this battery cell enabled a long cycle life of 900 with all-time energy efficiencies more than 80%, exceeding state-of-art Na-O2 and Na-air batteries. The outcome of our study reveals the significance of the proper cell components design in Na-O2 battery technologies as a promising venue in energy conversion and storage systems.

(Invited) Towards the Development of High-Performance Crystalline Rutile Iridium Dioxide Electrocatalysts for the Oxygen Evolution Reaction

Proton exchange membrane water electrolysis (PEMWE) offers a promising route for the production of green hydrogen from renewable energy sources and could be the master key to unlocking a future sustainable energy system (1). One of the main barriers delaying the wide-spread adoption of PEMWE technologies is the slow kinetics of the oxygen evolution reaction (OER) occurring at the anode and the need for high-cost, low-abundance precious metal electrocatalysts. Iridium-based oxides are still considered the only feasible option for practical applications due to their high activity and considerable corrosion stability under the harsh electrochemical reaction conditions. To improve the overall efficiency of PEMWEs, future electrocatalyst development strategies must concomitantly address performance metrics in terms of activity, stability and material cost.Towards enhancing iridium utilisation, efforts are aimed at increasing the electrochemical surface area of the catalyst per mass of iridium, thereby increasing the number of available electrocatalytic surface sites. In this regard, amorphous iridium oxide (IrOx) nanoparticles have been shown to achieve a high intrinsic activity (2). However, this comes at the expense of catalyst stability (3) and a loss of intrinsic electronic conductivity (4) associated with the lower degree of crystallinity. By maximising the dispersion of Ir-based nanoparticles, the use of high surface area support materials have also been shown to improve OER performance (5, 6).However, to address long-term stability concerns for Ir-based OER catalysts, highly crystalline rutile iridium dioxide (IrO2) materials may still offer the best prospects. The drawback of using this approach is that the formation of crystalline IrO2 nanoparticles often involves high temperature thermal oxidative treatment causing particle growth and loss of surface area, ultimately leading to decreased OER activities (7). Therefore, novel synthesis methods that retain a high degree of crystallinity without a loss of surface area for IrO2 nanoparticles are required.In this talk, we discuss two synthesis strategies geared towards the preparation of highly crystalline IrO2 nanoparticles with high OER performance. Firstly, we present a novel wet-chemistry synthesis method that avoids the use of reducing agents and eliminates the need for high temperature thermal oxidative treatment. The resultant nano-sized IrO2 nanoparticles were found to have excellent Ir mass-specific OER activity and durability attributed to the small nanoparticle size and high degree of crystallinity.Secondly, we present a novel metalorganic chemical deposition process as a simple, one-step preparation method for highly crystalline IrO2 nanoparticles supported on Sb-doped tin oxide (ATO) (8). The superior OER performance was attributed to the epitaxial anchoring of well dispersed, crystalline IrO2 nanoparticles onto the ATO support. We further discuss the versatility of the method to the application of other conductive oxide support materials such as indium tin oxide and F-doped tin oxide, with the ability of tuning the chemical state of the Ir-based nanoparticles by changing the reaction conditions, i.e., temperature and gas environment as well as the nature of the support.Finally, using a series detailed physico-chemical characterisation techniques to elucidate the nature the iridium phase, composition, morphology and structure, we relate these properties to the electrochemical activity and stability of the prepared materials for the OER. Herein, we highlight some of the challenges often encountered with the analysis of physical and electrochemical characterisation data for IrO2 nanoparticles, particularly when supported on other oxide materials. Acknowledgements This work is funded by the Department of Science and Innovation (DSI, South Africa) Impala Platinum Holdings Limited (Implats) and the Federal Minister of Education and Research (BMBF, Germany). References K. Ayers, Current Opinion in Electrochemistry, 18, 9 (2019). T. Reier, I. Weidinger, P. Hildebrandt, R. Kraehnert and P. Strasser, ECS Transactions, 58, 39 (2013). T. Binninger, R. Mohamed, K. Waltar, E. Fabbri, P. Levecque, R. Kötz and T. J. Schmidt, Scientific Reports, 5, 12167 (2015). M. Bernt, C. Schramm, J. Schröter, C. Gebauer, J. Byrknes, C. Eickes and H. A. Gasteiger, Journal of The Electrochemical Society, 168, 084513 (2021). H.-S. Oh, H. N. Nong, T. Reier, A. Bergmann, M. Gliech, J. Ferreira de Araújo, E. Willinger, R. Schlögl, D. Teschner and P. Strasser, Journal of the American Chemical Society, 138, 12552 (2016). A. Hartig-Weiss, M. Miller, H. Beyer, A. Schmitt, A. Siebel, A. T. S. Freiberg, H. A. Gasteiger and H. A. El-Sayed, ACS Applied Nano Materials, 3, 2185 (2020). J. Quinson, Advances in Colloid and Interface Science, 303, 102643 (2022). Z. S. H. S. Rajan, T. Binninger, P. J. Kooyman, D. Susac and R. Mohamed, Catalysis Science & Technology, 10, 3938 (2020).

Engineered Mesoporous Silica-Based Core-Shell Nanoarchitectures for Synergistic Chemo-Photodynamic Therapies.

Combinatorial therapies have garnered enormous interest from researchers in efficiently devastating malignant tumors through synergistic effects. To explore the combinatorial approach, multiple therapeutic agents are typically loaded in the delivery vehicles, controlling their release profiles and executing subsequent therapeutic purposes. Herein, we report the fabrication of core (silica)-shell (mesoporous silica nanoparticles, MSNs) architectures to deliver methylene blue (MB) and cupric doxorubicin (Dox) as model drugs for synergistic photodynamic therapy (PDT), chemotherapy, and chemodynamic therapy (CDT). MB, as the photosensitizer, is initially loaded and stabilized in the silica core for efficient singlet oxygen generation under light irradiation towards PDT. The most outside shell with imidazole silane-modified MSNs is immobilized with a chemotherapeutic agent of Dox molecules through the metal (Copper, Cu)-ligand coordination interactions, achieving the pH-sensitive release and triggering the production of intracellular hydrogen peroxide and subsequent Fenton-like reaction-assisted Cu-catalyzed free radicals for CDT. Further, the designed architectures are systematically characterized using various physicochemical characterization techniques and demonstrate the potent anti-cancer efficacy against skin melanoma. Together our results demonstrated that the MSNs-based core-shell nanoarchitectures have great potential as an effective strategy in synergistically ablating cancer through chemo-, chemodynamic, and photodynamic therapies.

Low-temperature propane oxidative dehydrogenation over UiO-66 supported vanadia catalysts: Role of support confinement effects

Overoxidation is the principal barrier against commercializing propane oxidative dehydrogenation (PODH) catalysts for propylene production. The current approach to reducing overoxidation, i.e., coating the non-selective support surface with a monolayer of active phase, can itself increase the probability of overoxidation of the produced propylene due to polymerization of active phase species. Incorporating the “confinement agents” onto the metal oxide support might be considered as an alternative solution to prevent hydrocarbons from reaching the support and overoxidizing. Herein, the UiO-66 metal–organic framework, which contains numerous organic ligands connected to the zirconia nodes, was used as support for the vanadia active phase to highlight the role of support's confinement effects on the overall catalytic performance toward the PODH. The UiO-66 supported vanadia catalysts with various vanadium loadings were fabricated via an ultrasonic-assisted wet impregnation procedure. The catalytic function is related to the underlying chemical processes at catalyst surfaces using physicochemical characterization techniques, PODH performance measurements, and machine learning tools. The results showed that the catalyst with a relatively low vanadia density of 2.7 nm−2, equivalent to less than half of the entire support surface coverage, could achieve propylene productivity of 4.43 gC3H6gcat-1h-1, propane conversion of 17.1%, and propylene selectivity of 49.7% at 350 °C.

Influence of mineralizer in the preparation of Bi2CuO4 sensor for the electrochemical evaluation of chlorogenic acid in various real-time samples

Bismuth copper oxide (Bi2CuO4) has been prepared with varied morphologies and explored as an electrode modifier for chlorogenic acid (CGA) electrochemical sensors. The mineralizer agents such as NaOH, KOH, and NH4OH served as a chemical agent and pH stabilizer in attaining variations in the morphology. The variation in the morphology attributes to the effect of viscosity of the corresponding mineralizer. The attained variation between the prepared Bi2CuO4 was revealed by different physicochemical characterization and electrochemical techniques. Bi2CuO4–KOH modified glassy carbon electrode (GCE) exemplifies an excellent redox performance, due to the higher ionic mobility and conductivity of KOH. The Bi2CuO4–KOH modified GCE was implemented towards the electrochemical sensing of CGA with the aid of differential pulse voltammetry (DPV). Further, it demonstrates exquisite electroanalytical performance including a wide linear range (0.05–556 μM) and nanomolar level detection (4.8 nM) with appraisable sensitivity of 0.22 μA/μM cm−2 for oxidation. In addition, the proposed sensor exemplifies higher selectivity with excellent repeatability, reproducibility, and stability. Moreover, the practical feasibility analysis with various real samples displays excellent recovery results for the electrochemical sensing of CGA.

Foreword to microcrystalline pathologies: combining clinical activity and fundamental research at the nanoscale

This contribution underlines the key role of physicochemical characterisation techniques in the area of medical research. The starting point centres on the Mid-InfraRed platform located at the Tenon hospital and dedicated to multidisciplinary functional investigations. In the last two decades, we have enhanced this platform by creating a network combining researchers from varied disciplines such as physicists, chemists, and clinicians. The resultant research dynamism is underscored by metrics such as 71 references in Pubmed and 129 in Web of Science, and the high impact of the journals in which we have published (New England Journal of Medicine, Kidney International, Chemical Review...). It is of paramount importance to disseminate these physicochemical techniques among young doctors, and to establish collaborations with appropriate private companies.

Microwave assisted synthesis of guar gum based biopolymeric macromolecule optimized as a flocculant for mineral ore processing

The research endeavour to synthesize a novel, non-toxic, eco-friendly guar gum based biopolymeric macromolecule, [2-(methacryloyloxy) ethyl] trimethyl ammonium chloride grafted guar gum (GG-g-P (MAETMAC)) that has been optimized as a flocculant for mineral ore processing. The synthesis was performed using non-radiation and microwave assisted technique to compare and ensure the superiority of the latter. The intended grafting of monomer[2-(methacryloyloxy) ethyl] trimethyl ammonium chloride on to the biological macromolecule (guar gum) was confirmed through standard physico-chemical characterization techniques namely X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV–visible) spectroscopy, intrinsic viscosity study, etc. The flocculation efficacy of the synthesized novel graft copolymer was thoroughly investigated in kaolin, coal fine, and iron ore suspensions. We have explored a graft copolymer, [2-(methacryloyloxy) ethyl] trimethyl ammonium chloride grafted guar gum that has not been studied yet to the best of our knowledge. To establish the superiority of the synthesized biomaterial, the flocculation study revealed that the best grade of the synthesized novel graft copolymer showed flocculation efficacy of 90 % in kaolin, 69 % in Iron ore, and 29 % in coal fine suspensions which was significantly higher than using alum as a coagulant which provided 36 % efficacy in kaolin, 29 % in iron ore and 10 % in coal fine suspensions.

Self-Assembled Maslinic Acid Attenuates Doxorobucin Induced Cytotoxicity via Nrf2 Signaling Pathway: An In Vitro and In Silico Study in Human Healthy Cells.

The clinical applications of some well-known chemotherapeutic drugs for cancer treatment have been restricted nowadays owing to their adverse effects on many physiological systems. In this experimental study, maslinic acid (MA) isolated from Olea europaea (Olive) fruit extract was used to mitigate the cytotoxicity induced by Doxorubicin (DOX) in human healthy peripheral blood mononuclear cells (hPBMCs). Self-assembled maslinic acid (SA-MA) was obtained in ethanol-water mixture (35.5 mM: 4:1 v/v). The morphology of SA-MA was analyzed by various physicochemical characterization techniques, which revealed its micro-metric vesicular architecture as well as nano-vesicular appearances. In this study, treatment of hPBMCs with DOX has been found to generate severe intracellular oxidative stress, which was significantly mitigated after pre-treatment with SA-MA. Alteration of hPBMC morphologies after DOX treatment was also restored notably by pre-treatment with SA-MA. Furthermore, pentoxifylline (TNF-α inhibitor) and indomethacin (COX-2 inhibitor) were used to investigate the responsible pathway by which SA-MA protected hPBMCs from DOX-induced cellular stress. Restoration of hPBMC viability above 92% in both cases confirmed that SA-MA protected the cells by inhibiting inflammatory pathways generated by DOX treatment. Subsequently, in molecular docking study, it was also evaluated that MA could successfully bind with the pocket region of Keap1, while Nrf2 was capable of upregulating cytoprotecting genes.

Synthesis and Characterization of Monodispersed Spherical Calcium Oxide and Calcium Carbonate Nanoparticles via Simple Pyrolysis.

In this study, calcium carbonate nanoparticles (CCNPs) and calcium oxide nanoparticles (CONPs) are synthesized by the carbonization/calcination of calcium oleate. CONPs are an essential inorganic material, and they are used as catalysts and as effective chemisorbents for toxic gases. CCNPs are widely used in plastics, printing ink, and medicines. Here, calcium oleate is used as a starting material for the preparation of CCNPs and CONPs. This calcium oleate is prepared from calcium hydroxide and oleic acid in ethanol under mild reflux conditions. The effect of the calcination temperature of calcium oleate is examined during the synthesis of CCNPs and CONPs. By simple carbonization/calcination, calcite-type CCNPs and CONPs are prepared at <550 °C and >600 °C, respectively. The synthesized nanomaterials are analyzed by various physicochemical characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) with derivative thermogravimetry (DTG), and scanning electron microscopy (SEM) with energy dispersive X-ray analysis. An X-ray diffractometer and the Scherrer formula are used to analyze the crystalline phase and crystallite size of prepared nanoparticles. TGA techniques confirm the thermal stability of the calcium oleate, CCNPs, and CONPs. The SEM analysis illustrates the dispersive behavior and cubic/spherical morphologies of CCNPs/CONPs. Furthermore, the obtained results are compared to the CCNP and CONP samples prepared using calcium hydroxide. As a result, the carbonization/calcination of calcium oleate produces monodispersed CONPs, which are then compared to the CONPs from calcium hydroxide. Additionally, from calcium oleate, CONPs can be prepared on a large scale in a cheap, convenient way, using simple equipment which can be applied in various applications.

Superlative photoelectrochemical properties of 3D MgCr-LDH nanoparticles influencing towards photoinduced water splitting reactions

In the present work, we report the synthesis of single system three-dimensional (3D) open porous structure of MgCr-LDH nanoparticles in a substrate-free path by using one-step formamide assisted hydrothermal reaction followed by visible light irradiation for significant photoelectrochemical (PEC) properties that manifest towards photocatalytic H2 and O2 production. The as-prepared nanostructured materials were characterized by various physico-chemical characterization techniques. Moreover, this unique synthetic approach produces 3D open porous network structure of MgCr-LDH nanoparticles, which were formed by stacking of numerous 2D nanosheets, for effective light harvestation, easy electronic channelization and unveil superlative PEC properties, including high current density (6.9 mA/cm2), small Tafel slope of 82 mV/decade, smallest arc of the Nyquist plot (59.1 Ω cm−2) and photostability of 6000 s for boosting water splitting activity. In addition, such perfectly self-stacked 2D nanosheets in 3D MgCr-LDH possess more surface active defect sites as enriched 50% oxygen vacancy resulting a good contact surface within the structure for effective light absorption along with easy electron and hole separation, which facilitates the adsorption of protons and intermediate for water oxidation. Additionally, the Cr3+ as dopant pull up the electrons from water oxidation intermediates, thereby displaying superior photocatalytic H2 and O2 production activity of 1315 μmol/h and 579 μmol/h, respectively. Therefore, the open 3D morphological aspects of MgCr-LDH nanoparticles with porous network structure and high surface area possess more surface defect sites for electron channelization and identified as distinct novel features of this kind of materials for triggering significant PEC properties, along with robustly enhance the photocatalytic water splitting performances.

Exploration on magnetic and electrochemical properties of nitrogen and phosphorus Co-doped ordered mesoporous carbon for supercapacitor applications

A series of heteroatom doped ordered mesoporous carbons (HOMCs) such as ordered mesoporous carbon (OMC), nitrogen doped ordered mesoporous carbons (NOMC), phosphorus doped ordered mesoporous carbons (POMCs), and nitrogen and phosphorus co-doped ordered mesoporous carbon (NPOMC) were synthesized via a chemical vapor deposition nanocasting (CVD nanocasting) route using SBA-15 as the template at 800 °C for high-performance supercapacitor. The formation of the template and HOMCs were confirmed by various physicochemical characterization techniques such as XRD, RAMAN, BET, SEM-EDAX, HR-TEM and XPS. The magnetic properties of prepared HOMCs were measured. Also, the electrochemical properties of HOMCs were evaluated using electrochemical analyses such as CV, EIS and GCD in 1 M H2SO4 medium. Among the various prepared HOMCs, sample NPOMC showed a high specific capacitance of 355 Fg-1 at a current density of 0.5 Ag-1 due to the heteroatoms. Moreover, the symmetric device fabricated using NPOMC exhibited 98% columbic efficiency with 98% capacitance retention after 1000 cycles at 2 Ag-1 current density.

Thermochromic properties of composite materials made from polylactic acid reinforced with recovered liquid crystals from waste LCD/LED laptops screens

The use of flat panel displays has permeated daily life since the breakthrough in the usage of liquid crystals (LCs) in display technology. However, the presence of chemical compositions such us cyano-groups, benzene, fluorine, cyclohexyl, etc., in LCs has potential adverse effects on humans and their environment as well. The environmental issue can be resolved by recovering the LCs for use in different applications. In this study, solvent extraction recovery process was directly used to simultaneously recover and purify LCs from waste liquid crystal display (LCD)/light emitting diode (LED) screens of laptops. The physicochemical (Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC)) and morphological properties (scanning electron microscopy (SEM)) of the purified and unpurified recovered liquid crystals (RLCs) were compared. The RLCs were incorporated in polylactic acid (PLA) using 0, 5, 10, 15, 20, 25 and 30 wt% of RLC. Thermochromic properties of the formulated PLA-RLC composites were studied from room temperature (25 °C) to 100 °C using a colorimeter. The changes in colour with change in temperature were measured and recorded. A recovery rate of 92.46% LCs was obtained from the laptop screens, making the purification process very effective as ascertained by the physicochemical characterization techniques. The difference in crystallinity of the purified and unpurified RLCs was 2.55% with the solid to liquid crystalline transition temperatures of the purified and unpurified RLCs being 45 °C and 65 °C, respectively. The thermochromic studies of the formulated PLA-RLC composites showed an appreciable colour change with temperature improvements in all the colour variables (i.e., the lightness, a* and b*). The colour changes were however not visible to the eyes due to the small energy difference (ΔE*) values. The implication of the results is that the RLC from waste screens of LCDs/LEDs exhibits enhanced thermochromic properties when different purification stages are used.