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Non-noble metal nanoparticles supported on biomass-derived N-doped carbons as efficient and selective catalytic systems in alcohols oxidation reactions.

Mechanochemically synthesized bismuth-based halide perovskites are reported as efficient and stable photocatalytic nanomaterials for vanillyl alcohol oxidation to vanillin.

Through this work, a family of sulfonamide functionalized mesoporous materials as sustainable heterogeneous catalysts has been successfully synthesized by employing sulfaguanidine, sulfathiazole, and sulfadiazine. The samples were fully characterized using a multitechnique approach. Such materials have proved to be highly versatile and catalytically active in both the advances in the hydrogenation of Levulinic acid through heterogeneous catalytic transfer hydrogenation (CTH) and oxidation reactions with a strong emphasis on discussing morphology and structure of versatile catalysts, plausible mechanism, and performance of the catalysts for biomass valorization of renewable feedstock. In particular, the prepared catalytic systems were tested in levulinic acid transformation into γ-Valerolactone, achieving a maximum conversion of 99% and a selectivity of 90% for the sulfaguanidine modified sample. The three nanocatalysts displayed good stability over four reuse cycles, and by considering the results of a hot filtration test, it is confirmed that the nature of the catalysis is heterogeneous as acid-base pairs and functionalized groups on catalytic activation of C–H and C O bonds for transfer hydrogenation of levulinic acid. Moreover, such samples also showed remarkable results in the oxidation of benzyl alcohol towards benzaldehyde, with conversion and selectivity values of 95% and 97%, respectively. The obtained catalytic results are highly promising for biomass upgrading processes, looking forward to a more sustainable future.

Bimetallic Pd-Ni catalysts were prepared via impregnation method, with effects of Pd/Ni ratio (wt%) on their catalytic performance for the oxidation of cyclohexane with molecular oxygen being investigated. Synthesized catalysts were characterized by a series of techniques including XRD, Nitrogen adsorption–desorption, H2-TPR, XPS, ICP-AES, TEM, SEM, and EDX. Compared to monometallic Pd, the addition of Ni to Pd was found to be effective in enhancing the selective oxidation of cyclohexane. Parameters such as the temperature of the reaction, reaction times, catalyst amount, initial oxygen pressure and different solvents were investigated. Optimum conditions to improve cyclohexane conversion and selectivity towards KA-oil (a mixture of cyclohexanone and cyclohexanol) over 4.0%Pd-4.0%Ni/KIT-6 catalyst included 140 °C, 1.0 MPa O2 and acetonitrile as solvent. Under these reaction conditions, 10.87 % conversion and 95.45 % selectivity for KA-oil were observed after 8 h of reaction. Reusability studies of the selected catalyst revealed an outstanding stability along four reaction cycles.

Herein, we report a Nb/ZnO nanocatalyst for the efficient conversion of levulinic acid, a platform molecule easily obtained from lignocellulosic biomass, to N-heterocycles under mild reaction conditions and the absence of solvent. Nb/ZnO nanocatalysts were synthesized by a mechanochemical-assisted and sacrificial template method, involving orange peel valorization toward nanostructured materials. Two different synthetic approaches, either one-step or two-step, as well as the amount of niobium deposited onto the ZnO support were investigated in order to obtain the nanocatalyst with the optimal catalytic properties. Results revealed the critical role of the niobium for LA conversion. The nanocatalyst containing 10 wt% of niobium and prepared following a two-step approach (10 %Nb/ZnO_2) exhibited the best catalytic performance with a 94.5% of conversion and 97.4% of selectivity towards one specific N-heterocycle compound. This work exemplifies the possibility of sustainable production of value-added compounds, in particular N-heterocycles, from biomass-derived feedstocks by playing with the design of improved catalysts. Importantly, this research area provides sustainable alternatives to the current chemical industry that is heavily dependent on fossil fuels.

Nature-inspired hierarchical architectures have recently drawn enormous interest in the materials science community, being considered as promising materials for the development of high-performance wearable electronic devices. Their highly dynamic interfacial interactions have opened new horizons towards the fabrication of sustainable sensing and energy storage materials with multifunctional properties. Nature-inspired assemblies can exhibit impressive properties including ultrahigh sensitivity, excellent energy density and coulombic efficiency behaviors as well as ultralong cycling stability and durability, which can be finely tuned and enhanced by controlling synergistic interfacial interactions between their individual components. This tutorial review article aims to address recent breakthroughs in the development of advanced Nature-inspired sensing and energy storage materials, with special emphasis on the influence of interfacial interactions over their improved properties.

Walnut shell residues have been used as a sacrificial template in the synthesis of TiO2-based materials via mechanochemical synthesis. To improve the photocatalytic efficiency of the synthesized ti...

This contribution reports the oxidation of HMF to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) employing Ag₂O, a relatively cheap and commercially available catalyst, to achieve an impressive HMFCA yield of 98% (60 min, 90 °C). Various reaction parameters including type of catalyst, base, quantities of base and catalyst, hydrogen peroxide concentration, and reaction temperature in function of reaction time have been optimized. Microwave batch conditions provided optimum yields, with quantitative HMF conversion with 97% HMFCA yield in only 24 min reaction (30 W). Reusability studies revealed catalyst deactivation, most likely associated with the reduction of silver oxide to metallic silver and nanoparticles sintering after the catalytic reaction.

Vascular calcification (VC), an unpredictable pathophysiological process and critical event in patients with cardiovascular diseases (CVDs), is the leading cause of morbi-mortality and disability in chronic kidney disease (CKD) patients worldwide. Currently, no diagnostic method is available for identifying patients at risk of VC development; the pathology is detected when the process is irreversible. Extracellular vesicles (EVs) from endothelial cells might promote VC. Therefore, their evaluation and characterization could be useful for designing new diagnostic tools. The aim of the present study is to investigate whether microvesicles (MVs) from endothelial cells damaged by uremic toxin and indoxyl sulfate (IS) could induce calcification in human vascular smooth muscle cells (VMSCs). Besides, we have also analyzed the molecular mechanisms by which these endothelial MVs can promote VC development. Endothelial damage has been evaluated according to the percentage of senescence in endothelial cells, differential microRNAs in endothelial cells, and the amount of MVs released per cell. To identify the role of MVs in VC, VSMCs were treated with MVs from IS-treated endothelial cells. Calcium, inflammatory gene expression, and procalcification mediator levels in VSMCs were determined. IS-treated endothelial cells underwent senescence and exhibited modulated microRNA expression and an increase in the release of MVs. VSMCs exposed to these MVs modulated the expression of pro-inflammatory genes and some mediators involved in calcification progression. MVs produced by IS-treated endothelial cells promoted calcification in VSMCs., Instituto de Salud Carlos III, Sociedad Española de Nefrología, Universidad de Alcalá, Grupo Santander, University fo California San Diego

The hydrogenation/hydrogenolysis of 5-hydroxymethylfurfural (HMF) has been carried out either under single (aqueous) phase or batch multiphase (MP) conditions using mutually immiscible aqueous/hydrocarbon phases, 5 % Ru/C as a catalyst, and both with and without the use of trioctylmethyl phosphonium bis-(trifluoro methane) sulfonimide ([P

Oxidation of 5-hydroxymethylfurfural (HMF) toward 2,5-furandicarboxylic acid (FDCA) was successfully performed under microwave (MW)-assisted heating using hydrogen peroxide (H2O2) as an oxidant. Va...

The present work deals with the extraction of phenolic compounds from biomass through microwave-assisted processes. In this case, green walnut shell residues have being studied for the extraction o...

In this work versatile boron–carbon nitride composite materials were synthesized and utilized in a sustainable process using sunlight as the energy source for the continuous-flow selective photocatalytic production of acetone from 2-propanol. It is worth highlighting that the sample preparation was carried out by an environmentally friendly strategy, without a solvent or additional reagents. Samples containing boron in 1–10 wt% were subjected to physico-chemical characterization using XRD, porosimetry, UVvisible spectroscopy, TEM, energy-dispersive X-ray spectroscopy and XPS. The reaction output was analyzed on the basis of the reaction rate, selectivity and quantum efficiency of the process. A correlation analysis between catalytic properties with two observables, the boron phase distribution in the materials and charge handling efficiency (measured using photoluminescence), rationalizes photoactivity. Such an analysis indicates that the presence of an amorphous boron metallic phase and its contact with the carbon nitride component are key to setting up a renewable and easily scalable chemical process to obtain acetone., MINECO (Spain) ENE2016-77798-C4-1-R, Consejo Superior de Investigaciones Cientificas (CSIC), Secretaria de Ciencia Tecnologia e Innovacion of CDMX (SECTEI, Mexico), MINECO CTQ2016-78289-P, European Union (EU), RUDN University Program 5-100

The demand for sustainable and robust catalysts for the valorisation of biomass is strictly related to the more and more pressing request to not only replace petroleum fuels with eco-friendly alternatives, but also to produce added value chemicals. In this context, the use of noble metals is not practically and economically sustainable and more abundant and stable alternatives are needed. In this contribution we have prepared and tested metal transition based catalysts (namely Ni3N and Ni nanoparticles) for the hydroconversion of levulinic acid (LA) as a model reaction. LA is useful also to produce valuable N-substituted pyrrolidones. Nanoparticles were prepared via a greener synthesis, using urea and metal salts, and have an average diameter of ∼30 nm (as ascertained by XRD and TEM studies). The main product of the levulinic acid hydroconversion was 1-ethyl-5-methylpyrrolidin-2-one. While this product was always the preferred one when Ni was used, Ni3N favoured the formation of the main product only in a shorter reaction time (below 1 h) with very high selectivity (up to 55% conversion), while a secondary product was formed in a longer time. The stability of the catalysts was also tested. To the best of our knowledge this is the first time that such a reaction is tested using transition metals and metal nitrides, with very promising results.

A graphitic carbon nitride nanostructure has been successfully functionalized by incorporation of different silver contents and subsequent modification with an α-rich protein, namely hemoglobin. Mechanochemistry has been employed, as an efficient and sustainable procedure, for the incorporation of the protein. A complete characterization analysis has been performed following a multitechnique approach. Particularly, XPS data exhibited considerable differences in the C 1s region for the Hb/xAg@CN, ensuring the successful protein anchorage on the surface of the graphitic carbon nitride-based materials. The as-synthesized nanomaterials delivered impressive performance toward hydrogen evolution reactions with an overpotential of 79 mV at a current density of 10 mA/cm2 for Hb/20Ag@CN nanohybrids, which is comparable with the most efficient HER electrocatalysts reported in the literature. The outstanding HER properties were associated with the unique synergistic interactions, quantitatively measured, between AgNPs, Hb tertiary architecture, and the graphitic carbon nitride networks.

Environmental harmful effects of spent coffee in stream waters pushed our research group to find new applications for this waste material. A new family of magnetic nanocatalysts was synthesized bas...

The aim of this tutorial review is to provide a general overview of processes, technologies and challenges in the production of pharmaceutical and bioactive compounds from food waste and lignocellulosic residues. Particular attention is given to benign-by-design processes instinctively devoted to environmental sustainability for the recovery of bioactive compounds from food waste as well as for the production of alcohols, acids, polyols, furans and aromatic compounds from lignocellulosic residues. At the same time, novel green synthetic routes for the production of active pharmaceutical ingredients and the development of novel bioactive compounds are discussed. Recent success industrial stories on the use of food waste and lignocellulosic residues for pharmaceutical and nutraceutical applications are also discussed. This journal is

A great emphasis is placed on searching for efficient sources to produce renewable fuels due to the actual trends in avoiding the use of fossil resources to mitigate the environment’s deterioration. Thus, the use of waste from the food or wood industry for the production of biofuels is widely researched and may contribute to sustainable general development. Rendered fat and Fischer-Tropsch waxes are high-energy materials which could be used for the pyrolysis reaction. Therefore, in this study, the effect of reaction parameters and feedstock composition on the distribution of the pyrolysis products has been examined. The experiments were carried out in a nitrogen atmosphere in a multi-shot pyrolizer instrument equipped with GC-FID. First, the influence of the temperature was examined at 785, 800, and 815 °C. The highest yield to olefins was observed at 815 °C. The effect of triglycerides and paraffins contents (0–100% with 10% ramp) in the feedstock on the product composition was investigated at 815 °C. The gas chromatography analyses revealed that the feedstock composition did not significantly affect the product composition due to the high temperature and the long linear chain structure similarities between the free fatty acids and Fischer-Tropsch waxes.

A highly sustainable method for the preparation of supported iron oxide and copper nanoparticles (NPs) on a biomass-derived carbon by solvent-free mechanochemical process is reported. In-situ mechanochemically obtained extracts from orange peel could behave as a green reducing agent, allowing the formation of Cu metal nanoparticles as well as generating a magnetic phase (magnetite) in the systems via partial Fe3+ reduction. At the same time, orange peel residues also served as template and carbon source, adding oxygen functionalities, which were found to benefit the catalytic performance of mechanochemically synthesized nanomaterials. The series of magnetic Cu-Fe@OP were tested in the oxidation of trans-ferulic acid towards vanillin, remarkably revealing a maximum vanillin yield of 82% for the sample treated at 200 °C.

In this work, we report the incorporation of nickel oxide nanoparticles into a metal–organic framework (MOF) structure by a solvent-free mechanochemical strategy. In particular, the zirconium-based MOF UiO-66 was modified with different Ni loadings and characterized using complementary techniques including X-ray diffraction (XRD), N2 porosimetry and X-ray photoelectron spectroscopy (XPS). The catalytic potential of the as-prepared Ni/UiO-66 materials in the hydrogenation reaction of methyl levulinate using 2-propanol as hydrogen donor solvent has been investigated under flow conditions. Under optimized conditions, the 5%Ni/UiO-66 led to the best catalytic performance (70% yield, 100% selectivity to gamma-valerolactone), which could be attributed to the higher content of the Ni species within the MOF structure. The obtained results are promising and contribute to highlighting the great potential of MOFs in biomass upgrading processes, opening the path to the sustainable development of the chemical industry.

Research on biomass valorization approaches demands endeavors from the scientific community, looking forward to more sustainable and renewable alternatives to the petro-based industry. In this regard, the group FQM-383 (NANOVAL), from University of Cordoba has dedicated many efforts, going from conventional heating approaches to continuous flow strategies, and to the use of unconventional technologies such as microwave and ultrasound irradiations. Moreover, investigations on biomimetic catalysis and photocatalysis have been also directed to the upgrading a biomass residues and derived platform molecules. Importantly, the investigations performed by our research group consider atom, cost and energy efficiency of a process, involving renewable feedstocks and catalytic steps.

In this work, we present the green Ni-MOF modification by the mechanochemical process in the solvent-free route that has been prepared as hydrogenation catalyst. The zirconium-based metal-organic framework UiO-66 (MOF) at different loading of Ni, were characterized using different techniques including X-ray diffraction (XRD), N2 porosimetry, X-ray photoelectron spectroscopy (XPS), have been employed for the characterization of the structural, textural, and composition properties of the synthesized materials, respectively. The catalysts have been evaluated in the hydrogenation reaction of methyl levulinate using 2-propanol as a hydrogen donor solvent. The reaction conditions were investigated and established at 30 bar system pressure with a reaction temperature of 200 ◦C using around 0.1 g of catalyst and a flow rate of 0.2 mL/min flow rate of a 0.3 M methyl levulinate solution in 2-propanol. All catalysts employed in this work exhibited good catalytic activities under the investigated conditions, with conversion values in the 30-70% range the selectivity to Υ-valerolactone was 100% for all samples (after one hour time on stream). The highest methyl levulinate conversion and selectivity was achieved by MOF-Ni5% which can be explained by the higher dispersion content of Ni species and the highest accessibility of the Zr sites of the MOF structures even when the superficial area has been reduced.

In this work, we studied the effect of alkali-activated zeolite foams modifications on properties and catalytic activity of cobalt phases in the process of catalytic decomposition of N2O. The zeolite foam supports were prepared by alkali activation of natural zeolite followed by acid leaching and ion exchange. The cobalt catalysts were synthesised by a different deposition technique (direct ion exchange (DIE) and incipient wetness impregnation (IWI) method of cobalt on zeolite foams. For comparison, catalysts on selected supports were prepared and the properties of all were compared in catalytic tests in the pellet form and as crushed catalysts to determine the effect of internal diffusion. The catalysts and supports were in detail characterized by a variety of techniques. The catalyst activity strongly depended on the structure of support and synthesis procedure of a cobalt catalyst. Ion exchange method provided active phase with higher surface areas and sites with better reducibility, both of these factors contributed to higher N2O conversions of more than 80% at 450 &deg, C. A large influence can also be attributed to the presence of alkali metals, in particular, potassium, which resulted in a modification of electronic and acid base properties of the cobalt oxide phase on the catalyst surface. The promotional effect of potassium is better reducibility of cobalt species.

Eggshell waste is among the most abundant waste materials coming from food processing technologies. Despite the unique properties that both its components (eggshell, ES, and eggshell membrane, ESM) possess, it is very often discarded without further use. This review article aims to summarize the recent reports utilizing eggshell waste for very diverse purposes, stressing the need to use a mechanochemical approach to broaden its applications. The most studied field with regards to the potential use of eggshell waste is catalysis. Upon proper treatment, it can be used for turning waste oils into biodiesel and moreover, the catalytic effect of eggshell-based material in organic synthesis is also very beneficial. In inorganic chemistry, the eggshell membrane is very often used as a templating agent for nanoparticles production. Such composites are suitable for application in photocatalysis. These bionanocomposites are also capable of heavy metal ions reduction and can be also used for the ozonation process. The eggshell and its membrane are applicable in electrochemistry as well. Due to the high protein content and the presence of functional groups on the surface, ESM can be easily converted to a high-performance electrode material. Finally, both ES and ESM are suitable for medical applications, as the former can be used as an inexpensive Ca2+ source for the development of medications, particles for drug delivery, organic matrix/mineral nanocomposites as potential tissue scaffolds, food supplements and the latter for the treatment of joint diseases, in reparative medicine and vascular graft producing. For the majority of the above-mentioned applications, the pretreatment of the eggshell waste is necessary. Among other options, the mechanochemical pretreatment has found an inevitable place. Since the publication of the last review paper devoted to the mechanochemical treatment of eggshell waste, a few new works have appeared, which are reviewed here to underline the sustainable character of the proposed methodology. The mechanochemical treatment of eggshell is capable of producing the nanoscale material which can be further used for bioceramics synthesis, dehalogenation processes, wastewater treatment, preparation of hydrophobic filters, lithium-ion batteries, dental materials, and in the building industry as cement.

Dimethyl carbonate (DMC) is a nontoxic compound currently prepared from CO2 as a building block, which displays a versatile reactivity for multiple applications including, particularly, the impleme...

In recent years, the incorporation of molecular enzymes into nanostructured frameworks to create efficient energy conversion biomaterials has gained increasing interest as a promising strategy owing to both the dynamic behavior of proteins for their electrocatalytic function and the unique properties of the synergistic interactions between proteins and nanosized materials. Herein, we review the impact of proteins on energy conversion fields and the contribution of proteins to the improved activity of the resulting nanocomposites. We address different strategies to fabricate protein-based nanocatalysts as well as current knowledge on the structure–function relationships of enzymes during the catalytic processes. Additionally, a comprehensive review of state-of-the-art bioelectrocatalytic materials for water-splitting reactions such as hydrogen evolution reaction (HER) and oxygen evolution reactions (OER) is afforded. Finally, we briefly envision opportunities to develop a new generation of electrocatalysts towards the electrochemical reduction of N2 to NH3 using theoretical tools to built nature-inspired nitrogen reduction reaction catalysts.

Polypyrrole-modified iron oxide nanomaterials have been synthesized employing a one-step hydrothermal protocol. The influence of the reaction temperature has been investigated by performing the synthesis at four different temperatures (Ppy@Fe2O3-120 °C, Ppy@Fe2O3-140 °C, Ppy@Fe2O3-160 °C, and Ppy@Fe2O3-180 °C). Synthesized materials exhibited an unprecedentedly peculiar morphology (star/coral reef-like architectures), induced by the presence of pyrrole in the reaction media. Full characterization of the samples revealed the critical influence of temperature on the crystallinity, textural properties and specially on (C+N)/Fe surface ratios in the materials. As-synthesized nanohybrids were integrated into electrodes to construct supercapacitor devices. A effective tuning of the electrochemical features was achieved by controlling the (C+N)/Fe ratio on the surface, strongly dependent on reaction temperature. The best electrochemical performance was reached by Ppy@Fe2O3-180 °C nanohybrid, which exhibited a re...

A protein-templated titania nanocomposite (PT-TiO2) was successfully synthesized by a water-free mechanochemical approach. A biomass valorization strategy was developed by employing egg white from ...

Furans represent one of the most important classes of intermediates in the conversion of non-edible lignocellulosic biomass into bio-based chemicals and fuels. At present, bio-furan derivatives are generally obtained from cellulose and hemicellulose fractions of biomass via the acid-catalyzed dehydration of their relative C6-C5 sugars and then converted into a wide range of products. Furfural (FUR) and 5-hydroxymethylfurfural (HMF) are surely the most used furan-based feedstocks since their chemical structure allows the preparation of various high-value-added chemicals. Among several well-established catalytic approaches, hydrogenation and oxygenation processes have been efficiently adopted for upgrading furans; however, harsh reaction conditions are generally required. In this review, we aim to discuss the conversion of biomass derived FUR and HMF through unconventional (transfer hydrogenation, photocatalytic and electrocatalytic) catalytic processes promoted by heterogeneous catalytic systems. The reaction conditions adopted, the chemical nature and the physico-chemical properties of the most employed heterogeneous systems in enhancing the catalytic activity and in driving the selectivity to desired products are presented and compared. At the same time, the latest results in the production of FUR and HMF through novel environmental friendly processes starting from lignocellulose as well as from wastes and by-products obtained in the processing of biomass are also overviewed.

A mechanochemical protocol was applied to the synthesis of a magnetic material based on iron oxide nanoparticles and Al-SBA-15. Full characterization of the prepared Fe2O3/Al-SBA-15 evidenced the effective functionalization of the aluminosilicate surface. Particularly, TEM analysis revealed that the mechanochemical protocol did not considerable affect the hexagonal ordered structure of Al-SBA-15. DRIFT experiments of Fe2O3/Al-SBA-15 showed interesting acidic properties, which can be further associated to a good catalytic performance. The catalytic behavior of the prepared material was tested in the oxidation of vanillyl alcohol to vanillin, displaying an excellent activity and selectivity. The material resulted to be highly stable in the aforementioned reaction, without considerable decrease of conversion after 10 reuse cycles.

The effective design of an active and stable catalytic system was performed by a simple modification of a commercial titania with a low platinum loading. The prepared material was fully characterized by XRD, XPS, N2 adsorption–desorption measurements, ICP-MS, TEM and SEM analyses. Such techniques corroborated the successful incorporation of Pt onto the titania surface, without affecting its original structure, morphology and chemical nature. The obtained TiO2–Pt catalyst was effectively applied in several continuous flow reactions between nitriles and carbonyl containing compounds for amine preparation. Remarkably, conversion of levulinic acid, a biomass derived molecule, was achieved with outstanding conversion (87%) and selectivity (80%) to 1-ethyl-5-methylpyrrolidin-2-one. The catalytic system demonstrated a high stability through 120 min of reaction. Moreover, the effect of the nitrile was investigated by performing the reaction with benzonitrile and ethylcyanoacetate. The TiO2–Pt catalyst was also tested in the conversion of benzaldehyde, displaying remarkable results. The influence of substitution in the aromatic ring was investigated using p-nitro-benzaldehyde and p-chloro-benzaldehyde.

A carbonaceous material with desirable properties for lithium-ion batteries (LIBs) was successfully obtained using a low cost and eco-environmental approach based on the mechanochemical dry milling of spent coffee grounds (SCG) followed by further carbonization at 800 °C. The spent coffee grounds derived carbon material (C-SCG) was employed as anodic material delivering a specific capacity of 360 mAh g−1 in the second cycle at current density of 0.1 A g−1. Additionally, the C-SCG material exhibited a competitive anode performance with a reversible capacity of 285 mAh g−1 and a remarkable coulombic efficiency nearly to 100% from the 2nd cycle. The resulting LIBs showed remarkable capacities retention over 100 cycles with a decay rate per cycle of 0.23%. This work contributes to the development of eco-environmental batteries using low-cost materials as a promising solution for increasing energy storage demands.

A wide majority of the organic–inorganic hybrid perovskites employed in photovoltaics contain Pb, which is a negative issue due to its high toxicity and the low stability of the Pb-based three-dimensional (3D) perovskites. The double perovskites or “elpasolites” with the formula A2BB′X6 arise as an alternative to avoid the use of Pb, however, not many of the theoretically predicted structures have been synthesized so far due to several synthetic issues, such as, the formation of stable side products. Herein, we report the synthesis of three double perovskites, Cs2AgBiBr6, MA2TlBiBr6 and Cs2AgSbBr6, through a highly efficient and reproducible mechanochemical approach: the high energy ball milling. This synthetic approach does not require the use of organic solvents, so it is a greener method compared to those reported for other double perovskites. The Cs2AgBiBr6 and MA2TlBiBr6 double perovskites were synthesized with high purity as proved by X-ray diffraction (XRD) and X-ray fluorescence (XRF) measurements. However, the Cs2AgSbBr6 double perovskite was obtained in mixture with Cs3Sb2Br9, a side product of the reaction. Several attempts to prepare the Cs2AgSbBr6 double perovskite by using other synthetic methods have been unsuccessful due to the low formation enthalpy of the Cs3Sb2Br9 side product and only the hydrothermal method afforded Cs2AgSbBr6 in mixture with other compounds. We believe that the low temperature required in the ball milling synthesis is the key factor that allows the formation of the antimony double perovskite. Cs2AgSbBr6 is a brown powder with a bandgap energy of 1.93 eV as shown with diffuse reflectance measurements. The three powders exhibit a very high stability with no changes at all in the crystal structure after several months of storage at room temperature and ambient humidity.

The oxygen evolution reaction (OER) plays a key role in the water splitting process and a high energy conversion efficiency is essential for the definitive advance of hydrogen-based technologies. Unfortunately, the green and sustainable development of electrocatalysts for water oxidation is nowadays a real challenge. Herein, a successful mechanochemical method is proposed for the synthesis of a novel hemoglobin (Hb) modified Co

Control of electron-transfer (ET) processes across electrochemically active biomaterials by tuning the surface properties of platform materials plays a key role in the design of highly efficient bi...

In this work, two different strategies have been employed to explore the potential valorization of biomass waste. A TiO2-based sample was prepared by a dry-milling strategy, involving orange peel valorization toward nanostructured materials. Subsequently, ruthenium deposition was accomplished by a chemical reduction method to obtain different ruthenium loadings on the titania support. The prepared catalysts were characterized using a multitechnique approach in terms of chemical, structural, and morphological properties. Levulinic acid, a typical model molecule associated with lignocellulosic biomass, was subsequently converted into N-heterocycles in a continuous flow reactor. The prepared Ru-TiO2 systems exhibited outstanding catalytic performance in terms of conversion and selectivity in comparison with Ru/P25 and Ru/C catalytic references. Maximum activity (79% conversion, 85% selectivity to 1-ethyl-2-(ethylideneamino)-5-methylpyrrolidin-2-ol) was achieved for the sample containing 3 wt % Ru, homogeneou...