http://ricaxcan.uaz.edu.mx/jspui/handle/20.500.11845/1410 2026-04-11T19:26:43Z http://ricaxcan.uaz.edu.mx/jspui/handle/20.500.11845/3263 Título : Experimental Investigation of the Reaction Network of Ethene to Propene over Ni/AlMCM-41 Catalysts Authors: Alvarado Perea, Leo; Felischak, Matthias; Wolff, Tanya; Hamel, Christof; Seidel-Morgenstern, Andreas Resumen : The reaction network of the ethene-to-propene (ETP) reaction over Ni/AlMCM-41 catalysts was studied. This reaction consists of the dimerization of ethene, the isomerization of 1-butene, and the metathesis of ethene and 2-butene to propene. This work focused on the latter. ETP experiments followed by in situ diffuse reflectance infrared Fourier transform spectroscopy were carried out. Metathesis activities were evaluated by the isomerization of butenes, the metathesis of ethene and 2-butene, and the retro-metathesis of propene. Metathesis activities of Ni/AlMCM-41 catalysts were not observed. Thus, a conjunct polymerization of ethene to propene is proposed. 2017-03-03T00:00:00Z http://ricaxcan.uaz.edu.mx/jspui/handle/20.500.11845/2404 Título : Synthesis of Alloyed CdxZn1-xS Quantum Dots for Photovoltaic Applications Authors: Solís Luna, Omar Eduardo; Rivas Martínez, Jesús Manuel; López Luke, Tzarara; Zarazua, Isaac; De la Torre y Ramos, Jorge; Esparza Salazar, Diego Resumen : This article describes the synthesis of Cdx Zn1- x S quantum dots prepared using the successive ionic layer adsorption and reaction method and incorporated into a photovoltaic device. The Cdx Zn1- x S quantum dots exhibit good optical and electrical properties. The photovoltaic device has the configuration TiO2 /Cd0.75 Zn0.25 S1 /ZnS. A photoconversion efficiency of 3.6% was obtained with this device. This efficiency corresponds to a 16% relative increment compared with a reference sample with the con- figuration TiO2 /Cd1 Zn0 S1 /ZnS. The improvement is associated with an increment in the open-circuit voltage (Voc) from 0.517 to 0.725 V. The corresponding short-circuit current density (Jsc) was reduced from 12.15 to 11.66 mA cm!2. Electrochemical impedance spectroscopy analyses confirm that the behavior of the device was due to a recombination rate reduction obtained as a result of surface passivation between the TiO2 layer and the CdxZnx-1S QDs interface. 2020-05-20T00:00:00Z http://ricaxcan.uaz.edu.mx/jspui/handle/20.500.11845/2403 Título : Celdas solares de tercera generación a base de puntos cuánticos y perovskitas Authors: Esparza Salazar, Diego; Torres García, Carlos Jeevan; Sánchez Díaz, Jesús Alberto; Rivas Martínez, Jesús Manuel Resumen : Las celdas solares de tercera generación son dispositivos fotovoltaicos fabricados con materiales de bajo costo y son atractivas debido a que reducen significativamente la razón costo/eficiencia. Este tipo de dispositivos son fabricados utilizando materiales semiconductores con estructuras a escala nanométrica, los cuales presentan propiedades ópticas y eléctricas muy interesantes, como es la sintonización de absorción de luz con el tamaño de la partícula y el trasporte de carga entre cada interface de los materiales. Las más estudiadas son: las celdas orgánicas, las sensibilizadas por puntos cuánticos y las celdas solares basadas en perovskitas. Cada tipo de tecnología presenta distintas formas de fabricación y distintas eficiencias. Las celdas solares sensibilizadas con puntos cuánticos actualmente presentan eficiencia de alrededor del 12%, mientras que las celdas de perovskita han llegado a tener hasta 24% de eficiencia. Descripción : Third generation solar cells are photovoltaic devices fabricated with low cost materials and are attractive because the cost to efficiency ratio is significantly reduced. These devices are fabricated using semiconductor materials with a structure in the nanoscale. At these dimensions, these materials present interesting optical and electrical properties. Light absorption can be tuned by controlling particle size and there is also charge transport at the interfaces of the materials. Among the most studied solar cells in this generation are: the organic solar cells, the quantum dot sensitized solar cells and the perovskite solar cell. Different technologies require different manufacturing methods and distinct efficiencies. The quantum dot sensitized solar cells have a record of 12%, while the perovskite solar cells have a record of 24% in photoconversion efficiency. 2021-01-15T00:00:00Z http://ricaxcan.uaz.edu.mx/jspui/handle/20.500.11845/2402 Título : Análisis de perovskitas libres de plomo a base de cesio-estaño por simulaciones en computadora Authors: Torres García, Carlos Jeevan; Rivas Martínez, Jesús Manuel; Esparza Salazar, Diego Resumen : Las celdas solares de perovskita se basan en la fórmula ABX3 donde A corresponde al material orgánico (comúnmente CH3NH3) B es el material inorgánico (Pb) y X es el halógeno (I, Br o Cl). Este tipo de celdas solares han atraído mucha atención en los últimos años debido a su rápido incremento en la eficiencia de fotoconversión (~25%), además de excelentes propiedades ópticas y viabilidad económica. En este trabajo, presentamos simulaciones y modelado computacional de las estructuras cristalinas de perovskita CsSnX3. Encontramos propiedades optoelectrónicas de esta estructura de perovskita, como la brecha energética. El software de simulación Materials Studio se usó para diseñar las estructuras cristalinas, mientras que el módulo CASTEP se usó para estimar la brecha prohibida. Este módulo emplea un algoritmo basado en la teoría funcional de densidad (DFT). El compuesto CsSnX3 busca mejorar la durabilidad de las celdas de perovskita al ser inorgánico, y se reemplaza el Pb por Sn para disminuir la toxicidad. Descripción : Perovskite solar cells are based on the ABX3 formula where A corresponds to the organic material (commonly CH3NH3) B is the inorganic material (Pb) and X is the halogen (I, Br or Cl). This type of solar cell has attracted much attention in recent years due to its rapid increase in photoconversion efficiency (~25%), as well as excellent optical properties and economic viability. In this work, we present simulations and computational modeling of the crystalline structures of perovskite CsSnX3. We find optoelectronic properties of this perovskite structure, such as the energy gap. The Materials Studio simulation software was used to design the crystal structures, while the CASTEP module was used to estimate the bandgap. This module uses an algorithm based on density functional theory (DFT). The CsSnX3 compound seeks to improve the durability of perovskite cells as it is inorganic, and Pb is replaced by Sn to decrease toxicity. 2021-01-15T00:00:00Z