Microwave-assisted valorization of pig bristles: towards visible light photocatalytic chalcocite composite

Waste valorization for the production of valuable materials is of great importance for sustainable development. Herein, a new green methodology for the synthesis of photocatalytically active copper sulfide (Cu2S) carbon composites using pig bristles is reported. The catalyst was prepared via microwave-assisted methodology using ethylene glycol as the solvent, pig bristles as the sulfur and carbon source, and copper chloride as the metal precursor. Cu2S carbon composites (denoted as pb-Cu2S, where “pb” stands for “pig bristle”) were characterized by XRD, N2 physisorption, EDX and UV-Vis spectroscopy. In order to validate the practical utilization of pig bristle-derived chemicals, the photocatalytic degradation of methyl red using pb-Cu2S was investigated under white, blue, green and red visible light irradiation

A Sustainable Approach for the Synthesis of Catalytically Active Peroxidase-Mimic ZnS Catalysts

Zinc sulfides are emerging as promising catalysts in different fields such as photochemistry or organic synthesis. Nevertheless, the synthesis of ZnS compounds normally requires the utilization of toxic sulfur precursors, e.g., thiourea which is a contaminant and carcinogenic agent. As a result, new green and sustainable synthetic methodologies are needed. Herein, an innovative, simple, and cheap approach for the synthesis of ZnS carbon composites is reported. Zinc acetate dihydrate was employed as metal precursor while wasted pig bristles were employed as carbon and sulfur source. The phase and the morphology of the compounds were analyzed by XRD, XPS, SEM, and EDX and the surface area was determined by nitrogen physisorption. ZnS carbon materials showed remarkable peroxidase-like catalytic activity for two different model reactions: the liquid-phase selective oxidation of benzyl alcohol and toluene to benzaldehyde (conversions up to 63% and 29% and selectivities up to 86% and 87%, respectively) using hydrogen peroxide as oxidant under microwave irradiation

Highly active catalytic Ru/TiO2 nanomaterials for continuous production of γ-valerolactone

Green energy production from renewable sources is an attractive but challenging topic to face the likely energy crisis scenario in the future. In the current work, a series of versatile Ru/TiO2 catalysts were simply synthesized and employed in continuous flow catalytic transfer hydrogenation of industrially derived methyl levulinate biowaste (from Avantium Chemicals B.V.) to γ-valerolactone. Different analytical techniques were applied in the characterization of the as-synthesized catalysts, including XRD, SEM, EDX, TEM and XPS etc. The effects of various reaction conditions (e.g. temperature, concentration and flow rate) were investigated. Results suggested that optimum dispersion and distribution of Ru on the TiO2 surface could efficiently promote production of γ-valerolactone, with 5% Ru/TiO2 catalyst providing excelling catalytic performance and stability as compared to commercial Ru catalysts

Facile synthesis of B/g-C3N4 composite materials for the continuous-flow selective photo-production of acetone

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-RConsejo Superior de Investigaciones Cientificas (CSIC)Secretaria de Ciencia Tecnologia e Innovacion of CDMX (SECTEI, Mexico)MINECO CTQ2016-78289-PEuropean Union (EU)RUDN University Program 5-10

Synergistic effect of graphitic-like carbon nitride and sulfur-based thiazole-linked organic polymer heterostructures for boosting the photocatalytic degradation of pharmaceuticals in water

A sulfur-based COF has been combined with graphitic carbon nitride (CN) in microwave-assisted synthesis to build a COF-CN heterostructure with enhanced photocatalytic activity. The prepared COF-CN heterostructures were fully characterized, analyzing the textural (N2 isotherms), structural (XRD and FTIR), chemical (elemental analysis and XPS), morphological (HR-STEM), optical (DRS-UV–Vis and photoluminescence) and electrochemical properties (EIS impedance, transient photocurrent, and flat band potential). Different COF-to-CN ratios (5–25 % of COF, wt.) were explored, defining a proportion (20 %) that led to optimum activity for the photocatalytic oxidation of organic contaminants of emerging concern (CECs) due to an enhanced separation of the photogenerated charges and lower bandgap value, 2.55 vs. 2.35 eV. The performance of the optimum COF-CN was further tested for other CECs, demonstrating its benefits compared to the bare CN. The materials displayed acceptable reusability and stability. The activation mechanism highlights the importance played by superoxide radicals and photogenerated holes

Surface CuO, Bi2O3, and CeO2 species supported in TiO2-anatase: Study of Interface Effects in Toluene Photodegradation Quantum Efficiency

The enhancement of active triggered by surface deposition of Cu, Bi, and Ce containing oxidic species onto a high surface area anatase is analyzed through the calculation of the quantum efficiency for toluene photodegradation under UV and Sunlight-type illumination. To this end, series of Cu, Bi, and Ce containing oxides supported on anatase were synthesized having a growing content of the Cu, Bi, and Ce surface species and characterized with X-ray diffraction and photoelectron, UV-visible, and photoluminescence spectroscopies as well as transmission electron microscopy. Utilizing the surface concentration of Cu, Bi, and Ce species as a tool, we analyzed the influence of the system physicochemical properties affecting quantum efficiency in anatase-based materials. First, employing small surface concentrations of the Cu, Bi, and Ce species deposited onto (the unperturbed) anatase, we provided evidence that all steps of the photocatalytic event, including light absorption, charge recombination, as well as surface interaction with the pollutant and chemical output as to activity and selectivity have significance in the quantitative assessment of the enhancement of the efficiency parameter. Second, we analyzed samples rendering maximum quantum efficiency within all these series of materials. The study indicates that maximum enhancement over anatase displays a magnitude strongly dependent on the efficiency level of calculation and would thus require the use of the most accurate one, and that it occurs through a balance between optoelectronic and chemical properties of the composite materials. The (Cu, Bi, Ce) oxide-anatase interface plays a major role modulating the optoelectronic properties of the solids and thus the efficiency observableFinancial support by MINECO (ENE2013-46624-C4-1-R) is gratefully acknowledge

Facile mechanochemical modification of g-C3N4 for selective photo-oxidation of benzyl alcohol

Graphitic carbon nitride enriched with ZnO or Fe2O3 were synthesized using a simple one-pot mechanochemical method. By using this method, composite samples were synthetized without the production of any potentially hazardous waste. The synthesized materials were used as catalysts during the selective photo-oxidation of benzyl alcohol. Both composite materials displayed an enhancement of the activity and benzaldehyde selectivity with respect to the pure g-C3N4. The most active catalyst was Fe2O3/g-C3N4. The conversion and benzaldehyde selectivity of this sample were 20 and 70 %, respectively. It showed a considerable increase of the benzaldehyde selectivity compared to the pure g-C3N4 and TiO2 P25 commercial reference. A complete structural and electronic characterization using Scanning Electron Microscopy-Energy Dispersive (SEM-EDX), BET measurements, X-ray diffraction (XRD), X-ray Photoelectron (XPS), and UV–visible spectroscopies was carried out. The characterization analysis pointed out the leading role of the crystallinity and surface concentration over the activity and benzaldehyde selectivity of the reactio

Versatile protein-templated TiO2 nanocomposite for energy storage and catalytic applications

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 expired eggs to control the morphology and textural features of the prepared titania. A remarkable enhancement of the surface area was achieved, in comparison with the synthesis of the material in absence of the biomass-derived template. Several techniques, such as scanning electron microscopy-mapping and CNHS analysis, supported the presence of carbon, nitrogen and sulfur residues in the obtained composite. Catalytic performance of PT-TiO2 was explored in the oxidation of diphenyl sulfide, displaying promising results in terms of conversion, selectivity and stability. The effect of the oxidant agent was additionally investigated by using hydrogen peroxide, urea hydrogen peroxide, oxygen and t-butyl-hydroperoxide. On the other hand, PT-TiO2 nanocomposite was successfully proved as anodic material for lithium-ion batteries delivering a reversible capacity of 107 mAh g–1 at 0.1C with an excellent Coulombic efficiency of 100% from the second cycle. In addition, the as-synthesized material showed significant capacity retention values of 76% among the 2nd cycle and 100th cycle. PT-TiO2 resulted to be a versatile material with potential catalytic and energy storage applications

Mechanochemically Synthesized Supported Magnetic Fe-Nanoparticles as Catalysts for Efficient Vanillin Production

Magnetically separable nanocatalysts were synthesized by incorporating iron nanoparticles on a mesoporous aluminosilicate (Al-SBA-15) through a mechanochemical grinding pathway in a single step. Noticeably, magnetic features were achieved by employing biomass waste as a carbon source, which additionally may confer high oxygen functionalities to the resulting material. The resulting catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, porosimetry, and magnetic susceptibility. The magnetic nanocatalysts were tested in the selective oxidative cleavage reaction of isoeugenol and vanillyl alcohol to vanillin. As a result, the magnetic nanocatalysts demonstrated high catalytic activity, chemical stability, and enormous separation/reusability qualities. The origin of catalytic properties and its relationship with the iron oxide precursor were analyzed in terms of the chemical, morphological, and structural properties of the samples. Such analysis allows, thus, to highlight the superficial concentration of the iron entities and the interaction with Al as key factors to obtain a good catalytic response

Thermal and light irradiation effect on the electrocatalytic performance of Hemoglobin modified Co3O4-g-C3N4 nanomaterials for oxygen evolution reaction

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 Co3O4/g-C3N4 composite nanomaterial. The controlled incorporation of cobalt entities as well as Hb functionalization, without affecting the g-C3N4 nanoarchitecture, was evaluated using different physicochemical techniques, such as X-ray diffraction, N2-physisorption, scanning electron microscopy, UV-visible spectroscopy and X-ray photoelectron spectroscopy. The beneficial effect of the resulting ternary bioconjugate together with the influence of the temperature and light irradiation was investigated by electrochemical analysis. At 60 °C and under light exposition, this electrocatalyst requires an overpotential of 370 mV to deliver a current density of 10 mA·cm−2, showing a Tafel slope of 66 mV·dec−1 and outstanding long-term stability for 600 OER cycles. This work paves a way for the controlled fabrication of multidimensional and multifunctional bio-electrocatalysts