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Bacterial and organic pollutants are major problems with potential adverse impacts on human health and the environment. A promising strategy to alleviate these impacts consists in designing innovative photocatalysts with a wider spectrum of application. In this paper, we report the improved photocatalytic and antibacterial activities of chemically precipitated Ag 3 PO 4 microcrystals by the incorporation of W at doping levels 0.5, 1, and 2 mol %. The presence of W directly influences the crystallization of Ag 3 PO 4 , affecting the morphology, particle size, and surface area of the microcrystals. Also, the characterization via experimental and theoretical approaches evidenced a high density of disordered [AgO 4 ], [PO 4 ], and [WO 4 ] structural clusters due to the substitution of P 5+ by W 6+ into the Ag 3 PO 4 lattice. This leads to new defect-related energy states, which decreases the band gap energy of the materials (from 2.27 to 2.04 eV) and delays the recombination of e'-h • pairs, leading to an enhanced degradation process. As a result of such behaviors, W-doped Ag 3 PO 4 (Ag 3 PO 4 :W) is a better visible-light photocatalyst than Ag 3 PO 4 , demonstrated here by the photodegradation of potential environmental pollutants. The degradation of rhodamine B dye was 100% in 4 min for Ag 3 PO 4 :W 1%, and for Ag 3 PO 4 , the obtained result was 90% of degradation in 15 min of reaction. Ag 3 PO 4 :W 1% allowed the total degradation of cephalexin antibiotic in only 4 min, whereas pure Ag 3 PO 4 took 20 min to achieve the same result. For the degradation of imidacloprid insecticide, Ag 3 PO 4 :W 1% allowed 90% of degradation, whereas Ag 3 PO 4 allowed 40%, both in 20 min of reaction. Moreover, the presence of W-dopant results in a 16-fold improvement of bactericidal performance against methicillin-resistant Staphylococcus aureus . The outstanding results using the Ag 3 PO 4 :W material demonstrated its potential multifunctionality for the control of organic pollutants and bacteria in environmental applications., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Defect-related luminescent materials have attracted interest because of their excellent optical properties and are considered as a less expensive and nontoxic alternative to commonly used lanthanide-based optical systems. These materials are fundamentally and technologically important for the next generation of full-color tunable light-emitting diodes as well as in the biomedical field. In this study, we report the preparation of α-silver vanadate (α-AgVO 3 , AV) decorated by hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , HA) with intense photoluminescence (PL) emissions at various HA/AV molar ratios (1:1-1:1/32) by a simple route based on chemical precipitation. The well-defined diffraction peaks observed by X-ray diffraction were all indexed to the monoclinic AV and hexagonal HA phases. Analysis of the results obtained by Fourier transform infrared spectroscopy reveals the presence of short-range structural order as deduced by the characteristic vibrational modes assigned to AV and HA systems. Characterization by scanning and transmission electron microscopies confirms the presence of AV and HA micro- and nanorods, respectively. UV-vis spectroscopy renders band gap energies of 5.80 eV for HA and in the range 2.59-2.65 eV for pure AV and HA/AV samples. The PL data reveal the presence of broad-band emission profiles, typical of defect-related optical centers in materials. Depending on the molar ratio, the emission can be completely tunable from the blue to red spectral regions; in addition, pure white color emission was obtained. On the basis of these results, we propose an order-disorder model induced by structural and interface defects to explain the PL emissions in the HA/AV system. Moreover, our results show that HA/AV composites have superior bactericidal activity against Staphylococcus aureus (methicillin-resistant and methicillin-susceptible) and can be used as a novel multifunctional material.

Bimetallic nanoalloys with a wide variety of structures and compositions have been fabricated through many diverse techniques. Generally, various steps and chemicals are involved in their fabrication. In this study, the synthesis of Ag-Bi nanoalloys by femtosecond laser irradiation of an inorganic oxide Ag 2 WO 4 /NaBiO 3 target without any chemicals like reducing agents or solvent is presented. The interaction between these materials and the ultrashort pulse of light allows the migration of Ag and Bi atoms from the crystal lattice to the particles surfaces and then to the plasma plume, where the reduction of the positively charged Ag and Bi species in their respective metallic species takes place. Subsequently, the controlled nucleation and growth of the Ag-Bi alloyed nanoparticles occurs in situ during the irradiation process in air. Although at the bulk level, these elements are highly immiscible, it was experimentally demonstrated that at nanoscale, the Ag-Bi nanoalloy can assume a randomly mixed structure with up to 6 ± 1 atom % of Bi solubilized into the face-centered cubic structure of Ag. Furthermore, the Ag-Bi binary system possesses high antibacterial activity against Staphylococcus aureus (methicillin-resistant and methicilin-susceptible), which is interesting for potential antimicrobial applications, consequently increasing their range of applicability. The present results provide potential insights into the structures formed by the Ag-Bi systems at the nanoscale and reveal a new processing method where complex inorganic oxides can be used as precursors for the controlled synthesis of alloyed bimetallic nanoparticles., Competing Interests: The authors declare no competing financial interest.