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In this work, La0.85Sr0.15–xBaxGa0.85Mg0.15O3–δ (LSBGM), with 0≤x≤0.075, were prepared as electrolytes for solid oxide fuel cells applications. The efect of barium and sintering temperature on the structure and electrical properties was studied. A fast combustion method was used, starting with nitrate salts and citric acid as fuel. The XRD spectra showed two main phases corresponding to LSGM orthorhombic (space group Imma) and LSGM-cubic (space group Pm-3 m). From literature, both structures are reported as high oxygen ion conductive species, but normally, they are not reported to appear together. Major secondary phases were LaSrGaO4, BaLaGaO4, and BaLaGaO7. SEM revealed a material with low porosity, indicating incomplete densifcation. The sample La0.85Sr0.075Ba0.075Ga0.85Mg0.15O3–δ showed a conductivity of 0.016 and 0.058 S cm−1 at 600 °C and 800 °C, respectively. This means an improvement of 34% compared to the non-barium sample La0.85Sr0.15Ga0.85Mg0.15O3-δ at 600 °C. Thus, this composition could be used in SOFC., This work was funded by the National Agency for Research and Development (ANID) / Scholarship Program/DOCTORADO NACIONAL/21202168.

Pt-nanoparticles supported on halloysite-nanotubes (HNTs) were selectively deposited onto the inner (Pt(IN)/HNT) or outer (Pt(OUT)/HNT) surface of the support to evaluate their operational stability on the cleaner and efficient hydrogenation of nitro compounds to produce their corresponding anilines. The formation of Pt0-aggregates on the inner or outer surfaces was observed, with mean particles sizes of 2.4–2.9 nm. The catalysts were evaluated using ethanol as solvent and nitrobenzene as a model substrate at a temperature of 298 K, under 1 bar of H2 pressure. The Pt(IN)/HNT catalyst showed better catalytic performance than Pt(OUT)/HNT, which was mainly attributed to the confinement effect of the Pt-nanoparticles inside the HNTs. However, the operational stability showed that Pt(OUT)/HNT retained its catalytic performance after 15 cycles, while the Pt(IN)/HNT catalyst suffered deactivation after the 5th cycle. The best catalytic system showed a moderate-to-high efficiency in the efficient hydrogenation of 7 nitro compounds used to produce their corresponding anilines, which are important pharmaceutical building blocks.

Platinum (Pt) and palladium (Pd) nanoparticles (NPs) supported on titanate nanotubes (TiNTs) Pt@TiNT and Pd@TiNT were prepared for the liquid-phase hydrogenation of nitroarenes at 25 °C Initially, TiNT was modified with 3-aminopropyl-trimethoxysilane to provide a strong anchoring site to trap the Pt and Pd NPs, which prevent the metal NPs from leaching. As-prepared 1 wt% of metal loading catalysts were characterized by transmission electron microscopy (TEM), nitrogen adsorption–desorption isotherms, X-ray diffraction, and X-ray photoelectron spectroscopy measurements. The TEM images confirmed that the Pt (1.70 ± 0.19 nm) and Pd (2.80 ± 0.43 nm) NPs were mainly confined into the channel of TiNTs. Both catalysts exhibited excellent catalytic performances for the reduction of nitrobenzene as a model compound under mild reaction conditions. The superior catalytic activity for the hydrogenation of nitroarenes is attributed to the small size of the Pt and Pd NPs. However, the operational stability showed that Pt@TiNT retained its catalytic performance after 10 cycles, while Pd@TiNT suffered deactivation by metal sintering after the sixth cycle. The Pt@TiNT system exhibited high efficiency in the hydrogenation of different substituted nitroarenes of pharmaceuticals interest, and it showed an excellent activity and selectivity toward the production of desired substituted anilines.

In this study, 250 nm sized porous anatase TiO2 nanospheres (TiO2 NSPs) composed of ∼ 10 nm sized anatase TiO2 nanoparticles are obtained through a green synthetic route and their surfaces have been decorated with 3–4 nm sized plasmonic silver nanoparticles (AgNPs). Photoluminescence studies confirm that the AgNPs presence on TiO2 NSPs surface effectively inhibits the radiative charge recombination and thus facilitates charge separation process at the Ag-TiO2 NSPs interface, causing an enhanced photocatalytic activity. About 92% of the ceftiofur sodium (CFS) antibiotic taken initially is oxidized by Ag-TiO2 NSPs upon 90 min white light irradiation, while Ag loaded Degussa P25 TiO2 nanoparticles effects only 71% CFS oxidation. The synergistic effect given by plasmonic AgNPs and the continuous framework of anatase TiO2 NPs contributes to inhibit the electron-hole recombination in the Ag-TiO2 NSPs. Oxidation products of CFS in different water sources and their eco-toxicity effects identified through LC-MS and microtox-bioassays, respectively, indicate that the obtained oxidation products are non-toxic compared to pure CFS. Therefore, porous Ag-TiO2 NSPs could be successfully applied in photocatalytic oxidation technologies, exploiting sunlight for the effective removal of pharmaceutical pollutants from wastewater.

A series of La0.6Sr0.4MnO3 (LSM) perovskite was made using the rapid solution combustion method, which was calcined by varying the temperatures. In order to determine how the calcination temperature affected the nanopowders produced and calcined at various temperatures, their microstructural, morphological, compositional, optical, and electrical properties were analyzed using corresponding characterization tools. The XRD results showed the coexistence of the rhombohedral polymorphs R-3c and Pm-3m for the perovskite phase under a calcination temperature of 1400 °C, which were eliminated with increased calcination temperature. The average grain size was found to increase with increasing calcination temperature. The EDS analysis showed better agreement of the stoichiometry with the theoretical composition. The apparent porosity decreased with increasing temperature due to the coalescence of sintering pores. The sample obtained after calcination at 1500 °C showed 10.3% porosity. The hardness also improved with increasing calcination temperature and reached a maximum value of 0.4 GPa, which matched the bulk density. A similar trend was observed in the resistivity studies as a function of temperature, and all the samples exhibited a low resistivity of ~1.4 Ω·cm in the temperature range of 500–600 °C. The optical characterization showed broad absorption at 560–660 nm and bandwidth values between 3.70 and 3.95 eV, according to the applied heat treatment., This research was funded by FONDECYT-ANID (project No. 1181703) for the financial support, University of Concepcion, Concepcion, Chile.

Herein, we aimed to obtain NiFe layered double hydroxide (LDH) with a controlled phase and surface morphology as a highly active and stable oxygen evolution catalyst via the electrochemical deposition method, which was thermodynamically stable for the oxygen evolution reaction (OER) in an alkaline medium. The NiFe-LDH sample was analyzed by sophisticated instruments and tested as an electrocatalyst on Toray carbon (TC). The NiFe-LDH electrocatalyst showed an excellent performance with lower overpotential of 0.27 V at 35 mA cm−2 and higher density of 125 mA cm−2 for OER in the 1 M KOH electrolyte solution. Moreover, the prepared catalyst exhibited unpredictable long-time stability for 700 h. From our knowledge, NiFe-LDH is a robust highly stable electrocatalyst compared to the recent reports.

Nowadays, there is a great demand for low-cost and highly active electrocatalyst for the production of clean renewable energy. However, most of the electrocatalysts are noble metal-based which are very costly and unstable. To counter this, electrochemical water splitting in energy storage systems is been widely applied, using non-noble metal-based nanostructured electrocatalysts. In this work, a novel noble metal-free MoSe2–Ni(OH)2 nanocomposite electrocatalyst is synthesized using a multi-step hydrothermal technique for efficient hydrogen evolution reaction (HER). The morphology, structural, chemical composition, and functional features of the synthesized nanomaterials were characterized using different techniques that include scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), and Raman analysis. The new developed MoSe2–Ni(OH)2 nanocomposite combines a high active surface area with a high chemical stability, generating a novel material with a synergistic effect that enhances water splitting process performance. Thus, an outstanding low Tafel slope of 54 mV dec−1 is accomplished in the hydrogen evolution reaction.

Cost-effective, efficient and stable electrocatalyst for water splitting in the acidic electrolyte medium has been developed. The acidic electrolyte could be a support for the high purity hydrogen production via water splitting. Accordingly, we have prepared the defect-rich titania nanostructure via electrochemical anodization and cathodization routes using the titanium plate, which showed highly effective and durable electrocatalyst of hydrogen evolution reaction (HER) in an acidic medium. This hybrid compound showed a low onset potential of −0.17 V for HER with a current density of −150 mA cm−2 in 1 M H2SO4. Moreover, the stability test has been performed with the defect-rich titania nanostructure as cathode for 6 h in the two electrodes system. © 2021 The Author(s). The authors extend their appreciation to the Deanship of Scientific Research, King Saud University for funding this work through Research Group no RG-1441-043 and funded by the Taif University Researchers Supporting Project number (TURSP-2020/04), Taif University, Taif, Saudi Arabia. One of the author Dr G. Murugadoss would like to thank Chancellor, President and Vice Chancellor, Sathyabama Institute of Science and Technology, Chennai for providing lab facilities and encouragement.

The development of the efficient photocatalysts with improved photoexcited charge separation and transfer is an essential for the effective photocatalytic H2 generation using light energy. So far, owing to the unique properties and characteristics, the transition metal phosphides (TMPs) have been proven to be high performance co-catalysts to replace some of the classic precious metal materials in the photocatalytic water splitting. In the present work, we report a novel copper phosphide (Cu3P) as a co-catalyst to form a well-designed fabricated photocatalyst with blacktrumpet mushroom-like ZnS semiconductor for the first time. The synthesis of Cu3P/ZnS consists of two-step hydrothermal and ball milling methods. The physical properties of the materials so prepared were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) analyses. In order to study the role of Cu3P, electrochemical impedance spectroscopy (EIS) measurements were used to investigate the photogenerated charge properties of ZnS. The experiments of photocatalytic production of H2 confirm that the Cu3P co-catalysts effectively promote the separation of photogenerated charge carriers in ZnS, and consequently enhance the H2 evolution activity. The 3% Cu3P/ZnS sample delivers the highest catalyst activity and the consistent H2 evolution rate is14,937 µmol h−1 g−1cat, which is 10-fold boosted compared to the pristine ZnS. The stability of the catalyst was tested by reusing the used 3% Cu3P/ZnS photocatalyst in five consecutive runs, and their respective activity in the H2 production activity was evaluated. A possible mechanism is proposed and discussed.

Multi-phase FeNiCoCuMo and FeNiCoCuNb high-entropy alloys were successfully synthesized via mechanical alloying and hot pressing. FeNiCoCuNb and FeNiCoCuMo formed a face-centered cubic solid solution for 15 and 30 hours of milling, respectively. At longer milling times, both alloys were constituted by amorphous phases. The samples hot-pressed at 1000 °C exhibited a major face-centered cubic phase and intermetallic phases: C14 Laves phase in FeNiCoCuNb alloy, and σ and µ phases in FeNiCoCuMo alloy. Semi-hard magnetism was found in sintered FeNiCoCuMo and FeNiCoCuNb alloys, associated with an extensive amount of phase boundaries. The FeNiCoCuMo alloy presented a saturation magnetization (Ms) of 62.63 emu g−1 and coercivity (Hc) of 40.69 Oe. By substituting Mo for Nb, the Ms value was reduced to 53.27 emu g−1, while the coercivity was increased up to 53.49 Oe. The presence of hard intermetallic phases and solid-solution strengthening led to high-hardness FeNiCoCu-based high-entropy alloys. Although Nb increased the microhardness and electrical resistivity of the alloy, it also reduced the soft magnetic properties of the alloys. Better magnetic properties were found by the addition of Mo, suggesting that tailoring its content could conduct to obtain an excellent balance between mechanical and soft magnetic properties in the FeNiCo-based high-entropy alloys.

Developing economically soft magnetic materials for high-performance electrical devices is indispensable. Here, we present the structural and magnetic properties of thermally reduced soft CuFe nanoparticles. The fcc cubic structure of iron-rich Cu 37 Fe 63 and their composition was confirmed by Rietveld refinement. Cu 37 Fe 63 nanoparticles exhibited high saturation magnetization and coercivity of 127 emu/g (142 emu/g) and 4.3 Oe (31 Oe), respectively, at 300 K (5 K). They showed transitions at ~34 and ~249 K due to the Kondo temperature of CuFe and minor fraction of CuFe 2 O 4 , respectively. The exchange coupling between Cu and Fe was not significant, as demonstrated by field-cooled magnetization curves at 5 K. The magnetocaloric effect (MCE) in the range of fields and temperatures was estimated whereas the maximum MCE of -8.71 × 10 -2 J.kg -1 .K -1 was achieved at 222 K. These soft magnetic materials, which exhibited stable high saturation magnetization with less heating effect during magnetization and demagnetization cycles, would be suitable candidates for magnetic applications., Brazilian Funding Agency FAPESP Postdoctoral Fellowship; 10.13039/501100001807-Thematic Project; 10.13039/501100002850-FONDECYT Postdoctoral Fellowship Award

Nanostructured metal vanadates have recently harvested enormous consideration among the researchers due to their remarkable performances in catalysis, electronic devices, energy storage, and conversion. In the present work, we have formulated a facile and template-free method to synthesize β-Cu2V2O7 nanorods and analyzed their characteristics by using various spectroscopy techniques. Copper and vanadium are the earth abundant, relevantly economical, and possess several oxidation states, which can render a broad range of redox reactions favorable for the electrochemical performance. The catalytic efficiency of the synthesized nanomaterial was assessed by the photocatalytic degradation of methylene blue (MB) as a model cationic dye under the visible light irradiation. At the irradiation time of 60 min, the catalyst showed the degradation efficiency of 81.85%, kapp (min− 1) of 0.0193 min−1 with the first-order kinetic model reaction. The electrochemical measurements were performed using a three-electrode configuration in 1M NaOH solution. The measured specific capacitance of Cu2V2O7 modified electrode was 269 F/g at 1 A/g with good stability and retention capacity of 89% after 4000 cycles that paved the way to consider β-Cu2V2O7 as prospective material for energy-storage applications.

The present study describes Zn metal incorporation within BiOI microsponge structures for the photocatalytic degradation of tetracycline (TC) antibiotics. Interestingly, Zn metal incorporation increased the band gap value of BiOI. At the same time, the photocatalytic degradation efficiency is increased due to the increment of photodegradation ability and the generation of hydroxyl radicals, and the decrement of the recombination rate. The Zn–BiOI microsponges showed ∼87 and 100% degradation at 10 and 1 mg L−1 of TC concentration, respectively. TC antibiotics degradation was pH-dependent, which increased with the pH of the TC solution. The synthesized Zn–BiOI microsponges were tested against both Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria and were found to effectively inhibit or kill both bacterial strains. Hence, it is concluded that the synthesized Zn–BiOI microsponges could potentially degrade the TC antibiotics.