We report here the sol-gel synthesis of Ln(Mn0.2Fe0.2Co0.2Ni0.2Cu0.2)O3 (Ln= La, Ce, Pr, Nd, Sm, and Gd) high-entropy perovskite oxide (HEPO) materials that have subsequently been tested for the dry reforming of methane (DRM) reaction. Among the six lanthanide-based HEPOs, the pure-phase La(Mn0.2Fe0.2Co0.2Ni0.2Cu0.2)O3 catalyst has shown the highest catalytic activity, with 86% methane conversion and 90% CO2 conversion for a 100 h DRM reaction with H2/CO similar to 1. Same catalyst synthesized by solution combustion synthesis route results in much lower activity behavior. The pristine HEPO phase of the catalyst decomposes in the DRM environment and can be regenerated from the individual oxide phases by in situ thermal treatment close to the phase formation temperature, without compromising the DRM activity. This outcome indicates an unusual reversible thermal switching between the pristine HEPO phase of the catalyst and the fragmented phases formed during DRM and highlights the need for further research into the function of the decomposed phases that are produced in situ. We have explored the structure-property correlation in the framework of an in situ generated nanocomposite at the molecular level of the promising HEPO catalyst.

Biogenic silica extracted from foxtail millet husk has been used as a sustainable matrix for preparing Mn–SiO2 and Sn–SiO2 composites with pollutant-specific functionality. Mn incorporation narrows the band gap to ∼3.1 eV and anchors Mn2+ within the amorphous network, enabling efficient UV-C-driven photoreduction of Cr(VI) and partial oxidative degradation of sulphanilamide. Sn remains surface-localised, generating Lewis-acidic sites that promote chemisorptive uptake of Basic Fuchsin, achieving 94.5% removal at near-neutral pH. Together, these materials address three pollutant classes, heavy metals, antibiotics and cationic dyes, through orthogonal pathways of redox catalysis (Mn–SiO2) and adsorption (Sn–SiO2), without relying on crystalline order or complex synthesis. Structural and spectroscopic analyses (BET, XRD, FTIR, XPS, and DRS) confirm distinct bonding environments and functional divergence between the two dopants. Kinetic modelling shows pseudo-first-order behaviour for Mn-assisted Cr(VI) reduction and pseudo-second-order adsorption for Sn-assisted dye removal. Although competitive-ion effects, reusability and intermediate toxicity were not evaluated, the results establish a proof-of-concept for designing multifunctional, low-cost composites from agricultural waste. This approach highlights the potential for scalable, application-specific remediation using rural biomass as a silica progenitor.

In the present work, the formation of self-assembled TiO2 nanotubes (NTs) by anodic oxidation on Ti-13Nb-13Zr alloy and its effect on calcium phosphate phase enrichment on the alloy is reported. Anodization has been carried out in an electrolyte containing sulfuric acid and hydrofluoric acid. As-formed nanotubes have been characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive x-ray (EDX) spectroscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS). It has been noted that the native oxide present on the sample is substituted with self-assembled TiO2 NTs arrays through the process of anodization. FESEM images show tubular morphology of nanotube arrays on anodized Ti-13Nb-13Zr alloy and white deposit corresponding to calcium phosphate is seen after immersing the sample in Hanks’ solution. The corrosion behavior of the anodized Ti-13Nb-13Zr alloy surface has been investigated with potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies in Hanks’ solution. The corrosion resistance of the anodized alloy sample is similar to that of the bare alloy sample. The effect of TiO2 NTs on the enrichment of calcium phosphate over the anodized alloy sample has been investigated through immersion in Hanks’ solution for a duration of 7 days. FESEM images of immersed samples show that the anodized alloy surface exhibits higher deposits of calcium phosphate phase in comparison with the bare Ti-13Nb-13Zr alloy substrate. XPS analyses of immersed sample reveal a greater concentration of calcium, phosphorus, and oxygen in hydroxide/phosphate form on the anodized sample when compared to the bare alloy substrate.

In recent days, it is crucial for the globe to shift fossil fuel energies to renewable energies such as hydroelectric, wind, solar, tidal, geothermal, etc. to mitigate global warming issues. Wind energy has been regarded as one of the renewable energy sources to rely on in the future. In this aspect, wind turbine blade maintenance is quite a challenge in tropical areas like India. One of the main reasons why wind turbine blades get damaged and produce less energy is solid particle erosion. In the present work, epoxy nanocomposite coatings reinforced with Al2O3, ZrO2, and CeO2 nanoparticle fillers have been applied on glass fiber reinforced polymer (GFRP) substrates using a simple spray coating method. These nanoparticles have been prepared in-house by solution combustion synthesis (SCS) route using urea, glycine, and oxalyl dihydrazide fuels, respectively. X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy have been used to characterize the materials and coatings. Epoxy coatings with different Al2O3, ZrO2, and CeO2 nanoparticle concentrations have been subjected to solid particle erosion resistance tests at impinging angles of 30 degrees, 60 degrees, and 90 degrees. ZrO2 and CeO2 nanoparticle-reinforced epoxy coatings show much better resistance to solid particle erosion than Al2O3-reinforced coatings. Estimated average erosion rates are 17 and 11.3 x 10-3 mm3 g- 1 , respectively, for epoxy coatings with 20 and 40 wt% ZrO2 nanoparticles. However, GFRP substrate and neat epoxy (EP) coating show much higher erosion rates with respect to nanoparticles-reinforced epoxy coatings. To ascertain a correlation between H3/E2 and the solid particle erosion rates of the coatings, nanoindentation tests have been carried out. Tensile strength and initial modulus of all the coatings are found to be directly proportional to the average erosion rates, whereas, elongation at break shows an inverse relationship with the average erosion rate. This correlation of mechanical properties with solid particle erosion performance can play a critical role in the development of realistic simulation of protective coatings for wind turbine blades.

A sustainable and innovative approach has been developed for synthesizing of Fe(0)/Fe2O3 composite nanoparticles (Fe(0)/Fe2O3NPs), utilizing the bark extract of the arjun tree (Terminalia arjuna) as a reducing and capping agent. This environmentally friendly Fe(0)/Fe2O3NPs was thoroughly characterized using various analytical techniques, including UV-Visible spectroscopy, FT-IR, PXRD, HR-TEM, SEM, and XPS. The nanoparticles were then evaluated as catalysts for facilitating the three-component Hantzsch reaction with acetylacetone, ammonium acetate, and substituted aldehydes, producing bioactive dihydropyridine derivatives. The catalyst exhibited high performance over approximately five cycles, with negligible loss in yield and catalytic efficiency. Additionally, a mechanistic pathway was proposed and elucidated through intermediate mass analysis, supported by Density Functional Theory (DFT) calculations.

ABSTRACT Saving thermal energy in a sustainable way is one of the important aspects of global energy conservation. Therefore, conservation of thermal energy by different means has been a topic of applied research in the last several years. In this direction, low‐density, low‐thickness, cost‐effective, and easily scalable thermal insulation paint coating containing power plant waste cenosphere has been developed in the present work. Cenospheres having low thermal conductivity are used as fillers in an epoxy matrix. The coating has been developed using simple spray coating method. Morphology, phase, and particle size of cenospheres have been characterized by field emission scanning electron microscopy, X‐ray diffractometry, and particle size analysis, respectively. Cenospheres show spherical morphology with mainly quartz and mullite phases. Chemical bonding and surface nature of the as‐prepared coating have been evaluated by Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy, respectively. The coating contains C–O, C–O–C, C–C, C=C, –CH 3 , C–N, N–H, –OH, Al–O–Si, Al–O–Al bonds, as well as Si 3+ , Si 4+ , C–O, C=O, O–C=O, Ca 2+ , Na + , and Al 3+ species on the surface of the coating. The thermal conductivity of epoxy‐cenospheres coating is in the range of 0.24 to 0.35 W m −1 K −1 for temperatures of 20 °C–200 °C. The thermal insulation property of the coating has been assessed using an indigenously built setup and the coating shows a temperature drop of 20 °C–27 °C, when the coating has been subjected to 200 °C hot air exposure for 5 to 20 min.

Tantalum and Tantalum Carbide (TaC) thin films are fabricated using pulsed DC magnetron sputtering from a Ta target in an argon-acetylene (C2H2) environment at room temperature. Precise control of the TaCx film composition was achieved, with minimal impact on the films' structure, morphology, and optical properties observed when varying C2H2 gas concentrations, ensuring high reproducibility rate. Ellipsometry analysis determined the complex refractive index of the TaCx films, enabling accurate reproduction of reflectivity spectra in both visible and infrared regions. As the knowledge of the refractive index is crucial for simulating optical structures, an optimised selective solar absorber (SSA) for use in concentrating solar-thermal power (CSP) systems was designed. It comprises TaC and SiN layers on a tungsten substrate; hence, it is capable of withstanding high temperatures. It has a solar absorptance of 0.96 and a thermal efficiency higher than 0.9 at 900 degrees C and 0.85 at 1100 degrees C for incident angles up to 50 degrees C for a concentration factor of 1000. Its large acceptance angle offers significant potential for energy production through heliostats where the incident angle may vary.

The study focuses on synthesizing a series of high-entropy spinel oxides (HESOs) and their potential role in the dry reforming of methane (DRM). A phase pure (Mn0.2Fe0.2Co0.2Ni0.2Cu0.2)Al2O4 HESO has demonstrated high catalytic activity, converting 97% CH4 and 99% CO2 during 100 h DRM with H2/CO similar to 1. Through characterization of the as-prepared and aged catalyst samples, we have shown that the initial spinel phase breaks down into constituent metal oxides in the reaction medium and then regenerates itself from the degraded phases by annealing nearly at the synthesis temperature. This is an intriguing observation, since the structural transformation does not alter the DRM activity. This result defines the unusual reversible thermal switching that takes place between the pristine HESO phase and the decomposed phases. It also highlights the need for further investigation into the role of the decomposed phases that are produced during DRM. To address this issue, we have investigated the structure-property relationship within the context of an in situ generated molecular level nanocomposite.

We have explored in this work the effect of chemical tailoring through simultaneous doping of Ni and Cu in a hercynite system for the dry reforming of methane (DRM). A series of nanodimensional (10-14 nm) hercynites have been prepared following solution combustion synthesis. The optimized sample, Ni0.08Cu0.07Fe0.85Al2O4, is reported to exhibit noteworthy coke-free conversions of 97% and 99% for CH4 and CO2, respectively, with a H2/CO ratio of similar to 0.8 at GHSV of 34000 mL g-1 h-1 and at similar to 800 degrees C. This investigation highlights the structural evolution of the hercynite-based catalyst with time on stream activity behavior. Characterization of the aged vs the as-prepared catalyst suggests in situ exsolution of the doped metal ions (Ni and Cu) together with a certain portion of Fe from the catalyst leading to formation of NiCuFe trimetallic alloy accompanied by the formation of gamma-Al2O3 along with the retention of a pristine hercynite phase. Alloying of the active component Ni with Cu and Fe in the presence of the spinels (FeAl2O4 and gamma-Al2O3) is shown to be beneficial in circumventing the difficulties of Ni-only catalysts in DRM. Interestingly, the residual carbon, present initially in the combustion-synthesized catalyst, gets diminished in the course of the reaction, suggesting Ni0.08Cu0.07Fe0.85Al2O4 as a promising catalyst for dry reforming of methane with a sustainable coke-resistant ability.

An innovative and environmentally sustainable approach is presented for the synthesis of cadmium oxide nanoparticles (CdONPs), leveraging the leaf extract of the pigeon pea plant (Cajanus cajan) as both reductive and capping agents. This environmentally friendly heterogeneous CdONPs was meticulously characterized through FT-IR, PXRD, HR-TEM, SEM-EDAX, XPS and UV-Vis spectroscopic analyses. These NPs were subsequently applied to facilitate the three-component Biginelli reaction using ethyl acetoacetate, urea, and substituted benzaldehydes for producing dihydropyrimidone derivatives in good to excellent yield. The methodology was tested for different aldehydes containing electron-withdrawing and electron-donating groups. The catalyst demonstrated consistent performance over approximately five cycles, exhibiting negligible loss in yield and catalytic potential. The proposed mechanistic pathway of the reaction was elucidated through intermediate mass analysis and further validated by Density Functional Theory (DFT) calculations and catalytic surface adsorption studies.

In recent years, wind energy has gained widespread attention and has been regarded as one of the renewable energy resources for the future. However, surface erosion of wind turbine blades, which are key components of wind turbines, can degrade the aerodynamic properties of blades, thereby, reducing the energy efficiency and service life. It has been estimated that wind turbine blade erosion can reduce annual energy production by 20-25% with severe erosion. In this sense, understanding and mitigating of leading edge erosion of wind turbine blades caused by rain and solid particles are critical to develop efficient technologies for wind turbine blades. To protect the wind turbine blades, various types of polymer-based coatings have been developed. In general, polymer composites offer excellent strength, durability, flexibility, ease of fabrication, and low cost. This comprehensive review is aimed to provide broad information and recent developments about the characteristics of leading edge erosion by rain and solid particles, their mechanisms, testing methods and associated standards, and development of erosion protection coatings for wind turbines. Updated advances in characteristics of polymeric protective coatings, process of coating development, coating materials, coating types, and simulation for the coating development against rain and solid particle erosions have also been addressed in this review.

This work underscores the development of an easily separable, very simple yet highly active heterogeneous Pd catalyst supported on Ni-Fe spinel oxide containing a low percentage of noble metal Pd (only 1 at.%) enabling the access to an advanced set of catalysts for Suzuki-Miyaura carbon-carbon (C-C) cross-coupling reaction that are not easily accessible with homogeneous catalysts. A series of catalytic experiments have revealed optimum reaction conditions for C-C coupling between aryl bromide and phenyl boronic acid. Among a set of prepared catalysts, NiPdFe-1 (Ni/Pd molar ratio=1:1) is found to be the most active catalyst for the coupling reaction completing in just about 30 min under mild reaction conditions like 100 degrees C using Na2CO3 as the base in a very common organic solvent, DMF. Interaction between the oxide support and Pd(0) makes the Pd surface more electron-rich which accelerates the rate-determining step of the C-C coupling reaction by faster electron transfer from Pd(0) to the aryl halides. Moreover, the catalyst is essentially heterogeneous, stable, magnetically separable and durable for several cycles without losing its activity. Good to excellent isolated yields have been obtained with a variety of functionalities on both the aryl bromide and phenyl boronic acid with varying electronic properties.

Present work reports solution combustion synthesis (SCS) of Co0.5Zn0.5Fe2O4 spinel ferrite, its chemical modification with polymethylmethacrylate (PMMA), synthesis of polyaniline (PANI), and electromagnetic interference (EMI) shielding properties of their composites. Both as-prepared and PMMA-modified Co0.5Zn0.5Fe2O4 adopt cubic spinel structure as shown by X-ray diffraction studies. Field emission scanning electron microscopy images show the agglomerated and microporous nature of the ferrites. High resolution transmission electron microscopy image of as-prepared Co0.5Zn0.5Fe2O4 shows lattice fringes related to (311) plane of the spinel structure. X-ray photoelectron spectroscopy studies reveal the presence of Co2+, Zn2+, and Fe3+ in tetrahedral and octahedral coordinations in the ferrite. EMI shielding properties are evaluated for PMMA-modified Co0.5Zn0.5Fe2O4 and PANI composites in different weight ratios. Composites containing PMMA-modified ferrite and PANI with 50:50 and 10:90 weight ratios show the best performance among all the composites in 2−20 GHz frequency range. Optimized PMMA-modified Co0.5Zn0.5Fe2O4 and PANI composite with the ratio of 10:90 shows shielding effectiveness (SE) values of −16.6 to −24.2 dB in 2−20 GHz frequency region.

Phosphine-free, air stable cobalt(ii) based complexes consisting of imino phenol ligands were synthesized and utilized as catalysts in the coupling reaction of alcohols with amines into imines following an acceptorless dehydrogenative pathway.

This work emphasizes the dry reforming of methane (DRM) reaction on citrate sol-gel-synthesized double perovskite oxides. Phase pure La2NiMnO6 shows very impressive DRM activity with H-2/CO = 0.9, hence revealing a high prospect of next-generation catalysts. Although the starting double perovskite phase gets degraded into mostly binary oxide phases after a few hours of DRM activity, the activity continues up to 100 h. The regeneration of the original double perovskite out of decomposed phases by annealing at near synthesis temperature, followed by the spectacular retention of activity, is rather interesting and hitherto unreported. This result unravels unique reversible thermal switching between the original double perovskite phase and decomposed phases during DRM without compromising the activity and raises challenge to understand the role of decomposed phases evolved during DRM. We have addressed this unique feature of the catalyst via structure-property relationship using the in situ generated molecular level nanocomposite.

Dry reforming of methane (DRM) was extensively studied on Cu-doped LaNiO3 catalysts. The main findings of this work are as follows: (i) thermal switching of the catalyst phase between the parent perovskite and molecular-level nanocomposite of individual components formed in situ during DRM, (ii) reusability of the catalyst with enhanced activity, and (iii) regeneration of the catalyst phase at a lower temperature than that required for the formation of the parent perovskite. The present investigation provides an extensive analysis and understanding of the DRM reaction using Cu-doped LaNiO3 compared to the result reported by Moradi et al., (Chin. J. Catal., 2012, 33, 797-801) and hence provides new insights into its catalytic activity. Phase-pure LaNi1-xCuxO3 catalysts, specifically LaNi0.8Cu0.2O3, exhibited high catalytic activity towards the DRM reaction (97% CH4 and 99% CO2 conversion with an H2/CO ratio of ∼1.4-0.9). Remarkably, although the initial perovskite phase primarily decomposed into its component phases after DRM, its catalytic activity was barely affected and maintained even after 100 h. The regeneration of the initial perovskite from the disintegrated binary phases via annealing at temperatures even lower than the synthesis temperature together with the amazing retention of activity was very intriguing. The parallel activity of the pristine perovskite and its degraded binary mixtures makes it difficult to identify the actual components responsible for the DRM activity. Accordingly, we have explained the sustained activity of the degraded perovskite catalyst in the context of nanocomposite formation at the molecular level in the reforming atmosphere with the availability of Ni0 and NiO, as revealed by the thoroughly characterized samples in the as-prepared, aged, and regenerated forms.

Cyclohexane oxidation into a ketone-alcohol mixture (KA oil) or adipic acid is an industrially significant reaction. Transition metal (TM) ion, as a core component of supported metal oxide catalysts, plays a significant role in cyclohexane oxidation. The mechanism of interaction between the transition metal ion and C-H bond in cyclohexane remains unexplored in the literature. In this study, various transition metal (Cr, Mn, Fe, Co, Ni, Cu, and Zn) ion-substituted CeO2 catalysts have been prepared, characterized, and tested for catalytic activities in cyclohexane oxidation using O2 as the oxidant. The average rate of cyclohexane conversion over the unit surface of the catalysts has been calculated to evaluate the intrinsic catalytic reactivity of the TM ions substituted in the CeO2 lattice. The average rate, normalized with respect to the number of Cr ions over the unit surface (in 10% Cr/CeO2), was the parameter to find the most active TM ion for the reaction. The mechanistic pathway of C-H activation over the TM ions-substituted CeO2 catalysts has been supported by DFT calculations, indicating the formation of a reactive cyclohexene intermediate for the first time. Therefore, the rates of conversion of cyclohexane and cyclohexene over the Cu/CeO2 catalyst have been calculated to determine the relative reactivity of the intermediate. The reactivity of the metal ions, in terms of the average rate of conversion, has been correlated to the electronic state of the doped transition metal ions.

A novel green synthesis of cellulose/Ag nanocomposites (Cell/XTLL Ag NCs) with in situ generated silver nanoparticles using Xenostegia tridentata (L.) leaf extracts (XTLL). The synthesized nanocomposites have been appreciably characterized by SEM, TEM, FT-IR, XRD, UV-Vis spectrometer, AFM, DRS, XPS, TGA, and ICP-OES. The Ag nanoparticles found for the Cell/XTLL 60 mM AgNO3 have an average particle size of 33.78 nm. Moreover, Cell/XTLL Ag NC film, prepared with 60 mM AgNO3, suggests greater antioxidant activity. The most potent cell/XTLL 60 mM AgNO3 against Escherichia coli, Staphylococcus aureus, Trichoderma viride, and Fusarium oxysporum has strong antimicrobial activity and the best antimicrobial properties due to the fact that because the concentration of AgNO3 solution increased, the zone of inhibition additionally accelerated. The Cell/XTLL 60 mM becomes examined in vitro for its ability of human tumor cell growth inhibitory impact on human breast cancer cell line MCF-7 using MTT assay. The catalytic activity of Cell/XTLL 60 mM AgNO3 was assessed by the photocatalytic degradation of methylene blue and compared with bare cellulose. The Ag NPs are homogeneously unfolded out in Cell/XTLL 60 mM AgNO3 which leads to low electron-hole recombination and accelerated dye adsorption. In particular, 100 mg of Cell/XTLL 60 mM AgNO3, as catalyst, showed excellent photocatalytic activity with the efficiency of 91% degradation of methylene blue (MB).

Solar energy harvesting in solar thermal systems using different solar absorber coatings on collectors has been widely studied. Here, we incorporate a single layer Si (similar to 250 nm) onto one of the most common and cost-effective collector materials, i.e., stainless steel (SS304) to improve its optical performance by thermal treatment. During the heating cycle, the samples were heated at 900 degrees C for short durations and suddenly quenched to room temperature in air. A high solar absorptance of 0.92 along with an emittance of 0.37 were obtained after heat-treatment. The reflectance studies showed reduced uniform reflectance (<10%) over the entire UV-Vis-NIR region and high reflectance in the far IR region. The morphology, composition, and crystal structures were studied in detail. The Si layer and the quenching process aided in the formation of a highly irregular microstructure consisting islands of Cr-Fe-Mn-Si oxides and silicides (with trace amount of Ni) which in turn increases surface roughness. This irregular array of islands of varying sizes and varying gaps between them helps in increasing absorptance due to multiple reflections, scattering and diffraction effects. Similar studies carried out on SS202 substrates resulted in different surface morphology and hence different absorptance (0.84), suggesting that the surface morphology and absorptance are highly dependent on the substrate composition. The initial thermal stability data on heat-treated Si/SS304 suggests stability up to 700 degrees C in air for 1000 hrs. Our studies indicate that thermal treatment of Si/SS304 for a short duration is a plausible solution to develop cost effective high temperature solar thermal collectors.