Hydrazine modified g-C3N4 with enhanced photocatalytic activity for degradation of indigo carmine

Polymeric graphitic carbon nitride (g-C3N4) was obtained from urea and modified by heat polymerization at 550 °C in the presence of hydrazine as a modifier agent. The influence of in-situ generated NH3 by hydrazine decomposition at different contents (0.5, 1, 1.5, and 2 mL) on the physicochemical properties and surface properties (water contact angle and point of zero charge) of the g-C3N4 were investigated. The modified g-C3N4 were analyzed by X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, photoluminescence, Fourier Transform Infrared, water contact angle, surface area, and the point of zero charge. The in-situ generated NH3 induced an evolution from nano-flakes to lamellar plate morphology depending on stacked interplanar. The influence of surface properties on the photocatalytic response of the unmodified and modified g-C3N4 was tested in the photodegradation of indigo carmine dye at pH = 3.5 and 6.5 solutions under blue LEDs light. The photostability of the samples was tested after 4 cycles of reaction. The properties (surface area (SA); water contact angle (WCA), and optical gap) influence the photocatalytic response, which was summarized in a single parameter defined as SA/(WCA*gap). The maximum value of this product match with results obtained for the most active photocatalyst (U-Hz1).Fil: Valencia, Karen. Universidad Nacional Autónoma de México; MéxicoFil: Hernández Gordillo, Agileo. Universidad Nacional Autónoma de México; MéxicoFil: Mendez Galvan, Melissa. Universidad Nacional Autónoma de México; México. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Morett, Diego. Universidad Nacional Autónoma de México; MéxicoFil: Rodil, Sandra E.. Universidad Nacional Autónoma de México; Méxic

Exploring the CO2 conversion into hydrocarbons via a photocatalytic process onto M-doped titanate nanotubes (M = Ni and Cu)

A combined theoretical and experimental work was performed to assess the carbon dioxide (CO2) evolution reaction into short chain hydrocarbons. The theoretical calculations were performed by using Density Functional Theory (DFT) at the DFT + U level. The reaction mechanisms were elucidated with the string method by comparing the photocatalytic behavior of the pristine Ti-NT surface, previously synthesized in our group, and the M -doped Ti-NT (M -Ti-NT, where M = Cu, Ni) systems. For the pristine material, the results showed lower adsorption energies of the CO2 molecule (−0.27 eV), as compared to that obtained with the M -doped Ti- NT systems. Ni-Ti-NT showed an enhancement in photocatalytic performance with respect to the other surfaces, by yielding small activation energies throughout the reaction path. On the experimental side, Ti-NT and M-Ti-NT (M = Cu, Ni) materials were characterized through several techniques to assess their structural, morphological, textural, and optoelectronic properties. The photocatalytic CO2 reduction was evaluated under wavelength illumination between 440–540 nm. The liquid solar fuel identified products were HCOOH, CH2O, and CH3OH, showing a different distribution among photocatalysts which correlates with the position of the conduction band of the photocatalysts. Doping with Cu and Ni of the Ti-NT structure enhances the carriers’ density which improves the photoactivity mainly in the case of Ni-Ti-NT. The photocatalytic experimental results agree with the theoretical calculations.Fil: Celaya, Christian A.. Universidad Nacional Autónoma de México; MéxicoFil: Mendez Galvan, Melissa. Universidad Nacional Autónoma de México; México. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Castro Ocampo, O.. Universidad Nacional Autónoma de México; MéxicoFil: Torres Martínez, Leticia M.. Universidad Autónoma de Nuevo León; MéxicoFil: Luévano Hipólito, Edith. Universidad Autónoma de Nuevo León; MéxicoFil: Díaz de León, Jorge Noé. Universidad Nacional Autónoma de México; MéxicoFil: Lara García, Hugo A.. Universidad Nacional Autónoma de México; MéxicoFil: Díaz, Gabriela. Universidad Nacional Autónoma de México; MéxicoFil: Muñiz, Jesús. Universidad Nacional Autónoma de México; Méxic