Dr. Valdés-Morales, Héctor

Bismuth oxyiodide (BiOI) has received much attention in the design of materials, because this material has proved its potential application in heterogeneous photocatalysis for environmental decontamination processes using visible light or simulated solar radiation. In this study, standard conditions and a reproducible method of solvothermal synthesis are established in order to obtain BiOI microspheres with higher photocatalytic activity in the degradation of gallic acid. Standard conditions of reaction temperature and reaction time turn out to be 126 C and 18 h, respectively. In addition, results show that reaction temperature has a stronger influence on different properties of the BiOI, affecting the photocatalytic efficiency. BiOI materials were synthesized by solvothermal process using different ranges of reaction temperature (120–200 C) and reaction time (12–24 h). Eleven experiments were designed, applying response surface methodology. The morphological, optical, and chemical properties of the best and worst material were determined using several techniques.

BiOBr microspheres were obtained using a solvothermal synthesis route in the presence of ethylene glycol and KBr at 145 °C, for 18 h. BiOBr microspheres were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), nitrogen adsorption-desorption isotherms analysis, diffuse reflectance spectroscopy (DRS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Additionally, the theoretical and experimental isoelectric points (IEP) of BiOBr nanostructured microspheres were determined, and pH's influence on the degradation of an anionic dye (methyl orange) under simulated solar radiation was analyzed. Results show that 97% of methyl orange is removed at pH 2 after 60 min of photocatalytic reaction. Finally, DRIFTS studies permit the proposal of a surface reaction mechanism of the photocatalytic oxidation of MO using BiOBr microspheres.