Recent progresses on metal halide perovskite-based material as potential photocatalyst

Recent years have witnessed an incredibly high interest in perovskite-based materials. Among this class, metal halide perovskites (MHPs) have attracted a lot of attention due to their easy preparation and excellent opto-electronic properties, showing a remarkably fast development in a few decades, particularly in solar light-driven applications. The high extinction coefficients, the optimal band gaps, the high photoluminescence quantum yields and the long electron–hole diffusion lengths make MHPs promising candidates in several technologies. Currently, the researchers have been focusing their attention on MHPs-based solar cells, light-emitting diodes, photodetectors, lasers, X-ray detectors and luminescent solar concentrators. In our review, we firstly present a brief introduction on the recent discoveries and on the remarkable properties of metal halide perovskites, followed by a summary of some of their more traditional and representative applications. In particular, the core of this work was to examine the recent progresses of MHPs-based materials in photocatalytic applications. We summarize some recent developments of hybrid organic–inorganic and all-inorganic MHPs, recently used as photocatalysts for hydrogen evolution, carbon dioxide reduction, organic contaminant degradation and organic synthesis. Finally, the main limitations and the future potential of this new generation of materials have been discussed. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Pb-free Cs3Bi2I9 perovskite as a visible-light-active photocatalyst for organic pollutant degradation

In our work, we employed Cs3Bi2I9 as a visible-light-active photocatalyst, synthesized with a low-temperature solvothermal method. The morphological and structural properties of the as-prepared perovskite were investigated, and the results were compared to previous studies to confirm its nature and the quality of the synthesis procedure. Transient absorption spectroscopy was applied in order to investigate the generation and lifetime of photogenerated charge carriers, revealing their formation after visible light excitation. The potential photocatalytic activity of the as-prepared metal halide perovskite was applied for the removal of Rhodamine B in aqueous solution, demonstrating an excellent activity of 93% after 180 min under visible-light irradiation. The current research aims to provide insights into the design of a new visible-light-active photocatalyst, Cs3Bi2I9, selected for its high application value in the field of advanced materials for light harvesting. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Recovery of REEs from exhausted fluorescent lamps

REEs are widely considered as critical materials for several reasons. Exhausted fluorescent lamps are special WEEE and rich secondary sources of REEs. The main purpose of this thesis is to get the advantages of a pretreatment of sieving on the lamps' powders. Analysis are performed with ESEM, FT-IR, XRD and TDGA. Different acid extractions, complex formation and relative boundary conditions are tested; a microwave treatment is performed to investigate the efficiency in the recovery of REE

Recent Progresses on Metal Halide Perovskite-Based Material as Potential Photocatalyst

Recent years have witnessed an incredibly high interest in perovskite-based materials. Among this class, metal halide perovskites (MHPs) have attracted a lot of attention due to their easy preparation and excellent opto-electronic properties, showing a remarkably fast development in a few decades, particularly in solar light-driven applications. The high extinction coefficients, the optimal band gaps, the high photoluminescence quantum yields and the long electron–hole diffusion lengths make MHPs promising candidates in several technologies. Currently, the researchers have been focusing their attention on MHPs-based solar cells, light-emitting diodes, photodetectors, lasers, X-ray detectors and luminescent solar concentrators. In our review, we firstly present a brief introduction on the recent discoveries and on the remarkable properties of metal halide perovskites, followed by a summary of some of their more traditional and representative applications. In particular, the core of this work was to examine the recent progresses of MHPs-based materials in photocatalytic applications. We summarize some recent developments of hybrid organic–inorganic and all-inorganic MHPs, recently used as photocatalysts for hydrogen evolution, carbon dioxide reduction, organic contaminant degradation and organic synthesis. Finally, the main limitations and the future potential of this new generation of materials have been discussed

An Emerging Visible-Light Organic–Inorganic Hybrid Perovskite for Photocatalytic Applications

The development of visible-light active photocatalysts is a current challenge especially energy and environmental-related fields. Herein, methylammonium lead iodide perovskite (MAIPb) was chosen as the novel semiconductor material for its ability of absorbing visible-light. An easily reproducible and efficient method was employed to synthesize the as-mentioned material. The sample was characterized by various techniques and has been used as visible-light photocatalyst for degradation of two model pollutants: rhodamine B (RhB) and methylene-blue (MB). The photo-degradation of RhB was found to achieve about 65% after 180 min of treatment. Moreover, the efficiency was enhanced to 100% by assisting the process with a small amount of H2O2. The visible-light activity of the photocatalyst was attributed to its ability to absorb light as well as to enhance separation of photogenerated carriers. The main outcome of the present work is the investigation of a hybrid perovskite as photocatalyst for wastewater treatment

Digitally Printed AgNPs Doped TiO2 on Commercial Porcelain-Grès Tiles: Synergistic Effects and Continuous Photocatalytic Antibacterial Activity

In the present study, we use commercial digitally printed ceramic tiles, functionnalized by AgNPs doped micro–TiO2, to investigate the mechanism of Ag in the continouos photocatalytic antibacterial activity. The novelty of the research lies in the attempt to understand the mechanism of Ag, supported on TiO2, able to exhibit the same antibacterial activity of a standard system containing Ag species, but here, totally embedded on the tile surface, and thus not free to move and damage the bacteria cell. UV/vis diffuse reflectance spectroscopy (DRS) of AgNPs–TiO2 tiles indicated an enhanced visible light response, wherein a new absorption band was produced around 18,000–20,000 cm−1 (i.e., in the 400–600 nm range) owing to the surface plasmon resonance (SPR) of AgNPs. The antibacterial photocatalytic experiments were conducted towards the inactivation of E. coli under solar light and indoor light. It was found that the degradation speed of E. coli in the presence of AgNPs–TiO2 tiles is solar light-intensity depending. This justifies the semiconductor behavior of the material. Furthermore, the AgNPs–TiO2 tiles exhibit a high ability for the inactivation of E. coli at a high load (104–107 colony-forming unit (CFU)/mL). Additionally, AgNPs–TiO2 tiles showed a remarkable antibacterial activity under indoor light, which confirms the good photocatalytic ability of such tiles. On the basis of the reactive oxygen species (ROS) quenching experiments, O2•− species and h+ were more reactive for the inactivation of E. coli rather than •OH species. This is because of the different lifetime (bacteria are more likely oxidized by ROS with longer lifetime); in fact, O2•− and h+ exhibit a longer lifetime compared with •OH species. The generation of H2O2 as the most stable ROS molecule was also suggested

Anchoring lead-free halide Cs3Bi2I9 perovskite on UV100–TiO2 for enhanced photocatalytic performance

Halide perovskites have shown great potential in photocatalytic applications. In order to enhance the charge transportation efficiency, the chemical stability, and the light absorption ability, we anchored a lead-free halide perovskite (Cs3Bi2I9) on UV100–TiO2 nanoparticles to build a visible-light active photocatalysts. The as-prepared material exhibited excellent stability and a remarkable yield for photocatalytic oxidation of methanol to formaldehyde under visible light irradiation. The photocatalyst was characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, Brunauer–Emmett–Teller surface area measurement, and photoelectrochemical properties. The analyses confirmed a remarkable improvement of visible-light absorption, a favorable decrease in the recombination of photoinduced charge carriers, and a suitable bandgap for visible-light photocatalytic applications. Recycle experiments showed that the composites still presented significant photocatalytic activity after three successive cycles. A possible underlying mechanism of the composite accounting for the enhanced photocatalytic activity under visible light irradiation was proposed. Our study aims to open new possibilities of using lead-free halide perovskites for photocatalytic applications.Fil: Bresolin, Bianca Maria. Lappeenranta University of Technology; FinlandiaFil: Balayeva, Narmina O.. Leibniz Universitat Hannover; AlemaniaFil: Granone, Luis Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. Leibniz Universitat Hannover; AlemaniaFil: Dillert, Ralf. Leibniz Universitat Hannover; Alemania. Gottfried Wilhelm Leibniz Universität Hannover; AlemaniaFil: Bahnemann, Detlef W.. Leibniz Universität Hannover; Alemania. Gottfried Wilhelm Leibniz Universität Hannover; Alemania. Saint-Petersburg State University; RusiaFil: Sillanpää, Mika. Lappeenranta University of Technology; Finlandia. Florida International University; Estados Unido

Activation of Vegetable Oils by Reaction with Maleic Anhydride as a Renewable Source in Chemical Processes: New Experimental and Computational NMR Evidence

Vegetable oils are bio-based and sustainable starting materials that can be used to develop chemicals for industrial processes. In this study, the functionalization of three vegetable oils (grape, hemp, and linseed) with maleic anhydride was carried out either by conventional heating or microwave activation to obtain products that, after further reactions, can enhance the water dispersion of oils for industrial applications. To identify the most abundant derivatives formed, trans-3-octene, methyl oleate, and ethyl linoleate were reacted as reference systems. A detailed NMR study, supported by computational evidence, allowed for the identification of the species formed in the reaction of trans-3-octene with maleic anhydride. The signals in the 1H NMR spectra of the alkenyl succinic anhydride (ASA) moieties bound to the organic chains were clearly identified. The reactions achieved by conventional heating were carried out for 5 h at 200 °C, resulting in similar or lower amounts of ASA units/g of oil with respect to the reactions performed by microwave activation, which, however, induced a higher viscosity of the samples