Dr. ALFONSO RAMIREZ
Chemistry, Universidad del Cauca, Popayán, Cauca, Colombia
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Academic Career Length
58Years (1969-Present)
(Calculated once Scilit publication data is synced: current year − year of first publication + 1)
Representative Publications
View All Publications2 February 2021 in Scientific Reports
Journal Article
ALFONSO RAMIREZMMMarly Montero-Muñoz
Marly Montero-Muñoz
LLLizbeth L. López
Lizbeth L. López
JRJ. E. Ramos-Ibarra
J. E. Ramos-Ibarra
JCJose A. H. Coaquira
Jose A. H. Coaquira
CPCarlos A. Páez
Carlos A. Páez
+1
In this study we report, the synthesis of ZnO and its doping with Transition Metal Oxides -TMO-, such as Cr2O3, MnO2, FeO, CoO, NiO, Cu2O and CuO. Various characterization techniques were employed to investigate the structural properties. The X-ray diffraction (XRD) data and Rietveld refinement confirmed the presence of TMO phases and that the ZnO structure was not affected by the doping with TMO which was corroborated using transmission Electron microscopy (TEM). Surface areas were low due to blockage of adsorption sites by particle aggregation. TMO doping concentration in the range of 3.7–5.1% was important to calculate the catalytic activity. The UV–Visible spectra showed the variation in the band gap of TMO/ZnO ranging from 3.45 to 2.46 eV. The surface catalyzed decomposition of H2O2 was used as the model reaction to examine the photocatalytic activity following the oxygen production and the systems were compared to bulk ZnO and commercial TiO2-degussa (Aeroxyde-P25). The results indicate that the introduction of TMO species increase significantly the photocatalytic activity. The sunlight photocatalytic performance in ZnO-doped was greater than bulk-ZnO and in the case of MnO2, CoO, Cu2O and CuO surpasses TiO2 (P25-Degussa). This report opens up a new pathway to the design of high-performance materials used in photocatalytic degradation under visible light irradiation.
1 August 2018 in Applied Surface Science
Journal Article
MMMarly Montero-Muñoz
Marly Montero-Muñoz
JRJ.E. Ramos-Ibarra
J.E. Ramos-IbarraJRJorge E. Rodríguez-Páez
Jorge E. Rodríguez-PáezMTMarcio D. Teodoro
Marcio D. Teodoro
GMGilmar E. Marques
Gilmar E. Marques
JCJosé A. H. Coaquira
José A. H. Coaquira +4
1 May 2016 in Heliyon
Journal Article
CCCarlos M. Campo
Carlos M. Campo
JRJorge E. Rodríguez
Jorge E. RodríguezALFONSO RAMIREZA study was conducted on the transformation of SnO to SnO2 using X-ray diffraction and subjecting the SnO to heat treatments between 300 °C < T < 600 °C in two different atmospheres, argon and air. The intermediary oxide that appears in the disproportionation process was identified as Sn2O3. In an argon atmosphere, decomposition occurs in three stages: (1) a direct transformation of SnO to SnO2, (2) the formation of some intermediary Sn2O3 from SnO, and (3) the conversion of the Sn2O3 to SnO2 with the formation of metallic tin, Sn (l). When an atmosphere of air is used, however, a reaction occurs, concurrent with the decomposition reactions, that relates to the specific oxidation of the metallic tin produced in the course of the three process stages.
1 March 2015 in Journal of Molecular Catalysis A: Chemical
Journal Article
CMCristian D. Miranda M.
Cristian D. Miranda M.ALFONSO RAMIREZSJSonia Gaona Jurado
Sonia Gaona Jurado
CVCarlos R. Vera
Carlos R. Vera
Journal Article
MAMisael Córdoba Arroyo
Misael Córdoba ArroyoCMCristian Miranda
Cristian MirandaCLCecilia Lederhos
Cecilia LederhosFCFernando Coloma
Fernando ColomaAAAlba Nelly Ardila Arias
Alba Nelly Ardila AriasALFONSO RAMIREZ +2
Co3O4 particles were supported on a series of activated carbons (G60, CNR, RX3, and RB3). Incipient wetness method was used to prepare these catalysts. The effect of the structural and surface properties of the carbonaceous supports during oxidation of benzyl alcohol was evaluated. The synthetized catalysts were characterized via IR, TEM, TGA/MS, XRD, TPR, AAS, XPS, and N2 adsorption/desorption isotherm techniques. Co3O4/G60 and Co3O4/RX3 catalysts have high activity and selectivity on the oxidation reaction reaching conversions above 90% after 6 h, without the presence of promoters. Catalytic performances show that differences in chemistry of support surface play an important role in activity and suggest that the presence of different ratios of species of cobalt and oxygenated groups on surface in Co3O4/G60 and Co3O4/RX3 catalysts, offered a larger effect synergic between both active phase and support increasing their catalytic activity when compared to the other tested catalysts.
1 January 2018 in Journal of Photochemistry and Photobiology A: Chemistry
Journal Article
GLGéraldine L.-M. Léonard
Géraldine L.-M. Léonard
CPCarlos A. Pàez
Carlos A. PàezALFONSO RAMIREZ
Julien Guy MahyBHBenoît Heinrichs
Benoît Heinrichs
About Me
B.S., University of Valle, Colombia. 1993. Biology and Chemistry Education.
B.S., National Open and Distance University, Colombia. 2016. Chemist.
M.Sc., University of Valle, Colombia. 1998. Master of Sciences: Chemistry.
Ph.D., University of Poitiers, France. 2006. Philosophy Doctor: Applied Chemistry
Postdoctoral research, CLAF - Centro Latino-Americano de Física, Brasil. 2014-2015. “Síntese e caracterização de compostos nanoestruturados para a aplicação como catalizadores heterogéneos”
Postdoctoral Grant-Holder, Université de Liege, Bélgica. 2015. “Development of hydrothermal synthesis of mesoporous silicates” and “Bioinsipired Mo-Cu heterometallic clusters”
Visiting professor. Virginia Commonwealth University. Fall 2023- Fall 2024.
Professor. Department of Chemistry. University of Cauca, Colombia. 1998/Today. Classes in: Organic chemistry, heterogenous catalysis and general chemistry.
Assistent Scholarship/Assistent Professor. University of Valle, Colombia — 1994-1998. Classes in:
Organic chemistry. Laboratories in: General chemistry and organic chemistry.
Academic Staff. University of Gent, Belgium — September - 2010. Gas-phase photocatalytic oxidation of ethanol using systems doped with tin oxydes.
Academic Staff. University of Caldas, Colombia — March - 2009. Course: Heterogenous Catalysis. Principles and Aplications
https://orcid.org/0000-0002-7557-4047
https://www.scopus.com/authid/detail.uri?authorId=57704822500