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Photocatalytic materials can perform oxidative and reductive reactions over their surfaces when excited with light. Intrinsic characteristics of the material such as superficial area, morphological structure, and crystalline phase exposition play a fundamental role in the corresponding reaction paths. However, especially in doped semiconductors, as ZnO:N, less is known about how the synthesis parameters affect the morphologies and the photocatalytic activity simultaneously. To solve this issue, ZnO and ZnO:N samples were obtained using microwave-assisted hydrothermal and modified polymeric precursor methods of synthesis. Samples morphologies were characterized by TEM and FE-SEM. Crystallographic phases were observed by XRD and optical characteristics by DRS. XPS results confirmed the doping process. Degradation of Rhodamine-B and Cr(VI) reduction were employed as probe reactions to investigate their photocatalytic activity. Although the crystallographic structure of these powders maintains the ZnO hexagonal wurtzite structure, the optical properties and morphologies, and photocatalytic activities present different behaviors. Also, density functional theory calculations were employed to determine the specific features related to electronic structure, morphology, and photocatalytic activity.Different synthesis methods produce a singular behavior in the physicochemical properties of materials, and the doping effect produces various modifications in RhB degradation and Cr(VI) reduction for each synthesis method. Crystal face exposition and morphologies are related to the improvement in the photocatalytic activity of the materials.

Zinc oxide (ZnO) presents vast applicability in different areas. Diverse chemical elements are used in doping ZnO in order to modify desired properties-as proposed for enhanced visible photocatalytic activity through anion doping. Thus, the goal of this work is to develop a simple, fast and easy method for ZnO:N synthesis by a modified citrate precursor method. The as-prepared ZnO:N nanoparticles were utilized for dye photodegradation, in particular to study modifications in radical generation during photoactivation. The characterization of the nanoparticles confirms that the doping process affects neither particle morphology and crystalline structure, nor the bandgap of the samples. However, it largely affects photocatalytic activity for Rhodamine-B (Rhod-B) degradation, with an optimum N content for UV activity at 4% N and visible activity at 2% N. Under UV illumination, the photodegradation mechanism observed confirms that the ZnO:N nanoparticles presents clusters of p type ZnO:N embedded in n type ZnO particles endorsing the doping method as effective. These results enhance the essential comprehension of the photocatalytic activity of n type semiconductor doping processes and the modification of dye degradation mechanism related specially after doping.

In N-doping on TiO2 nanomaterial occurs a big decrease of band-gap (1 eV); however, its photocatalysis is low. We clarify such fact from effective mass, i.e., the electron–hole recombination is more than creation of electron–hole pair.

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The present study shows how electronic parameters (e.g. band gap energy, band edge positions) on semiconductors affect photoelectrochemical activity in simulated solar light using WO 3 , TiO 2 and WO 3 / TiO 2 as model systems. Hydrothermal synthesis was conducted to study heterostructure (HE) formation, which the loading of WO 3 in TiO 2 structure were varied to 20, 40 and 80 wt%. Scanning electron microscopy images show that WO 3 and TiO 2 particles are in contact with each other and the synthesis method as well as the deposition method are appropriate for the formation of WO 3 /TiO 2 HE film. Important findings were obtained with a hole scavenger during photoelectrochemical characterization of WO 3 /TiO 2 -40 wt% film. This strategy was effective to clearly distinguish charge transport from charge separation, the essential mechanisms that affect water splitting which are often misinterpreted experimentally for HE. The hole scavenger experiment depicts the increase by 17.5% in photocurrent density for the WO 3 /TiO 2 -40 wt% film as compared to WO 3 film, corresponding to 210 and 12 mA cm À2 vs Ag/AgCl respectively. Additionally, this HE film showed water oxidation initiated at lower applied potentials and indicating that coupling of the materials resulted in optimization of band edge properties for water splitting with the increase on light absorption at the visible range. Flat band potential was determined by the Mott-Schottky plot and it indicated the difference of 1.08 V vs Ag/AgCl between TiO 2 and WO 3 potentials, which makes the charge injection from one structure to another effective and thermodynamically stable for charge separation. A charge carrier density of 1.59 Â 10 20 was observed for the WO 3 /TiO 2 -40 wt% and it supports the best photoelectrochemical performance for water oxidation.

The impact of fungal diseases and the development of antimicrobial agents against pathogenic fungi have emerged as a main global healthcare challenge. In this study, the antifungal activity of silver-loaded hydroxyapatite (Ag/HAP) nanocomposites (NCs) with different Ag content synthesized by a one-pot microwave-assisted solvothermal method was evaluated against sensitive and resistant Candida species. The NCs’ composition and morphology were characterized by X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and high-resolution transmission electron microscopy analysis. Antifungal studies were conducted by a microdilution method according to a protocol from the Clinical and Laboratory Standards Institute. The main inhibitory effect was observed against Candida krusei, with a minimum inhibitory concentration (MIC) of 31.2 μg/mL, followed by Candida parapsilosis sensu stricto and Candida tropicalis (62.5 μg/mL) and Candida glabrata and Candida albicans (125 μg/mL). Furthermore, a toxicity assay was performed in the in vivo model Galleria mellonella by bathing or inoculating with the same NC concentration used in the previously mentioned microdilution experiments. For both approaches, all NC concentrations were not toxic in the in vivo model. The specific antifungal activity demonstrated that NCs act efficiently against species of Candida. These results show a potential antifungal application for well-designed nanostructured Ag/HAP composites.

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