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Pollution of waste and natural waters by antibiotics is a major health issue that induces the development of resistant pathogens. Pollutant may be removed by photocatalysis, yet classical photocatalysis is limited by the short carrier lifetime. Here, we review multicomponent photocatalysts for the synergic degradation of antibiotics. Components include metallic nanoparticles, semiconductors and adsorbents. The synergy of these components provide photocatalysts with advantages such as extended visible-light range with bandgap energy lower than 2.8 eV, improved charge transfer properties, enhanced adsorption capacity and more active reaction sites. The removal of the antibiotics, based on the decrease of the initial concentration, reaches 80–100%, but mineralization is rarely measured in reports. Proposed mechanisms for the photocatalytic degradation of antibiotics over single and multicomponent photocatalysts are discussed. [ABSTRACT FROM AUTHOR]

Bismuth vanadate, BiVO4, is a visible-light response semiconductor for photocatalysis applications such as organic pollutants degradation, oxygen production and carbon dioxide reduction. However, as a single-phase photocatalyst, BiVO4 efficiency is limited by the unpreferable recombination of the photoexcited electron (e−) and hole (h+). Thus, strategies have been designed to enhance the photocatalytic efficiency by promoting the separation of electrons and holes. This can be done by controling the morphology and crystallographic facets of BiVO4, and by building p–n junction photocatalytic systems with a combination of n-type semiconductors (BiVO4) and p-type semiconductors or a monoclinic–tetragonal heterostructure of BiVO4. In particular, a direct p–n junction photocatalytic system with tetragonal zircon-structured BiVO4 (t-z) and monoclinic scheelite-structured BiVO4 (m-s) combination has recently attracted attention. Here we review the synthesis of the monoclinic–tetragonal heterostructured BiVO4 photocatalyst (m–t BiVO4) by calcination, hydrothermal, microwave-assisted hydrothermal and solvothermal methods. m–t BiVO4 formation and the transmission phase between t-z and m-s are controlled by the calcining temperature, precursor pH, metal doping content, type of solvent, implementation of precursors and reaction conditions. We discuss m–t BiVO4 crystal structure, optical characteristics and photocatalytic principles. Successful formation of BiVO4 crystals with a m-s/t-z heterostructure is based on data from X-ray diffraction (XRD), Raman and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS). In the m–t BiVO4 heterostructure, a direct p–n junction photocatalytic system is established. When this system is exposed to visible light, the electrons in the conduction band of m-s BiVO4, a n-type semiconductor, migrate easily to the conduction band of t-z BiVO4, while the holes on valence band of t-z BiVO4, a p-type semiconductor, move to the valence band of m-s BiVO4 through an internal electric field. As a result, the e−/h+ charge carriers are spatially separated. [ABSTRACT FROM AUTHOR]

Energy security and pollution are becoming critical issues in the context of climate change and the circular economy, calling for sustainable resources. Asteraceae species, commonly referred as the aster, daisy, composite, or sunflower family, are among the largest flowering plants with 23,000 species belonging to 1600 genera, and are a major source of biomass. Here we review botanical characteristics and applications of Asteraceae for bioenergy, remediation, nanotechnology, medicine, food and agriculture. Sunflower is the most used to produce bio-oils with a yearly production of 47 million tons. Sunflower is also used for phytoremediation of heavy metals such as cadmium, lead, uranium, and chromium. Artichoke, chicory, purple coneflower, and wormwood display medicinal potential with 27–103 bioactive compounds. Artemisia, calendula, and sunflower oil are precursors for cosmetic and perfume production. Asteraceae species exhibited high efficiencies of 90−96% for removal of remazol red, and reactive blue dyes. Asteraceae species are used for fabrication of nanoparticles, biochar, activated carbon and biocomposites. [ABSTRACT FROM AUTHOR]