Author
Oscar Giraldo
Other affiliations: Facultad de Ciencias Exactas y Naturales, University of Connecticut
Bio: Oscar Giraldo is an academic researcher from National University of Colombia. The author has contributed to research in topics: Manganese & Zinc hydroxide. The author has an hindex of 19, co-authored 56 publications receiving 2067 citations. Previous affiliations of Oscar Giraldo include Facultad de Ciencias Exactas y Naturales & University of Connecticut.
Papers published on a yearly basis
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TL;DR: In this article, the synthesis, characterization, and applications of porous manganese oxides during the last two years have been discussed, including the synthesis of porous tunnel structures, layered structures, and related materials.
Abstract: This review concerns the synthesis, characterization, and applications of porous manganese oxides during the last two years The synthesis of porous tunnel structures, layered structures, and related materials is discussed Both microporous and mesoporous systems materials are covered here Characterization discussed here focuses around structural studies The focus of the application sections include electrochemical and catalytic studies
514 citations
TL;DR: In this article, a comparison of the economical and environmental performance of the ethanol production process from sugarcane and corn under Colombian conditions has been carried out, and the integration of these indicators into one index by using the analytical hierarchy process (AHP) approach was determined as the best choice for Colombian ethanol production facilities.
318 citations
TL;DR: In this article, an electron microscopy of manganese oxide nanoparticles with polycations poly(dimethyldially-lammonium) (PDDA) or myoglobin (Mb) onto silver, quartz, and rough pyrolytic graphite gave stable, porous, ultrathin films.
Abstract: Alternate adsorption of manganese oxide nanoparticles with polycations poly(dimethyldiallylammonium) (PDDA) or myoglobin (Mb) onto silver, quartz, and rough pyrolytic graphite gave stable, porous, ultrathin films. Quartz crystal microbalance (QCM) and UV−vis absorbance revealed regular film growth at each adsorption step for MnO2 and PDDA and for SiO2 nanoparticles and Mb. Scanning electron microscopy of MnO2/PDDA films showed smooth surfaces on the 20 nm scale and cross sections consistent with individual nanoparticles. QCM during growth of films of Mb and MnO2 reflected a competition for adsorption of the protein by the film surface and dispersed MnO2 nanoparticles. Nevertheless, films of Mb and MnO2 up to 30 nm thick on rough pyrolytic graphite electrodes could be constructed. These novel films featured reversible interconversion of the protein's heme FeIII/FeII redox couple with 10 electroactive layers of protein, considerably more than for polyion−Mb films on smooth gold (ca. 1.3 electroactive layers...
156 citations
TL;DR: In this article, the tetraalkylammonium hydroxides and diamines such as ethylenediamine, 1,6-diaminohexane, and 1,10diaminooctane were used to intercalate H-OL-1.
Abstract: Potassium manganese oxide materials having the synthetic birnessite structure K-OL-1 were synthesized by reduction methods. K-OL-1 has been ion-exchanged with H+ to produce H-OL-1, which was utilized in further intercalating reactions. The tetraalkylammonium hydroxides including tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide and diamines such as ethylenediamine, 1,6-diaminohexane, and 1,10-diaminooctane were used to intercalate H-OL-1. Elemental analyses, X-ray diffraction, FT-IR spectroscopy, scanning electron microscopy and energy-dispersive X-ray analysis, UV−vis spectroscopy, and transmission electron microscopy have been used to characterize the samples. Structural models of both wet and dry samples are given. The intercalation and deaquation processes of TAA and DA-OL-1 were studied. Their particle sizes were determined and nanometer-sized TAA-OL-1 samples were prepared in TAA systems.
115 citations
TL;DR: In this article, Raman spectroscopy, elemental analysis and CHN determination were used to verify the presence of enzymes on supports of chitosan biocatalytic systems.
108 citations
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Abstract: 3.
1,814 citations
TL;DR: The different technologies for producing fuel ethanol from sucrose-containing feedstocks (mainly sugar cane, starchy materials and lignocellulosic biomass) are described along with the major research trends for improving them.
1,792 citations
TL;DR: It is considered more feasible that the rate-deter-mining step is the cleavage of the C-H bond at the R-carbon atom, and the active site consists of an ensemble of metallic Auatoms and a cationic Au.
Abstract: ion from a primary OH group of glyc-erol. 223,231 A similar mechanism was proposed manyyears ago for alcohol oxidation on Pt/C, involving asecond step, the transfer of a hydride ion to the Ptsurface (Scheme 11). 8,87,237 We consider it more feasible that the rate-deter-mining step is the cleavage of the C-H bond at theR-carbon atom. A similar mechanism is now generallyaccepted for Au electrodes (Scheme 12). 238 Despite thestructural differences between Au nanoparticles andan extended Au electrode surface, there are alsosimilarities, such as the critical role of aqueousalkaline medium and the absence of deactivation dueto decomposition products (CO and C x H y frag-ments). 239,240 An important question is the nature of active siteson Au nanoparticles. Electrooxidation of ethanol onAu nanoparticles supported on glassy carbon re-quired the partial coverage of Au surface by oxides. 241 Another analogy might be the model proposed for COoxidation. 219,242,243 According to this suggestion, theactive site consists of an ensemble of metallic Auatoms and a cationic Au
1,784 citations
TL;DR: An asymmetric supercapacitor with high energy density has been developed successfully using graphene/MnO2 composite as positive electrode and activated carbon nanofibers (ACN) as negative electrode in a neutral aqueous Na2SO4 electrolyte as mentioned in this paper.
Abstract: Asymmetric supercapacitor with high energy density has been developed successfully using graphene/MnO2 composite as positive electrode and activated carbon nanofibers (ACN) as negative electrode in a neutral aqueous Na2SO4 electrolyte. Due to the high capacitances and excellent rate performances of graphene/MnO2 and ACN, as well as the synergistic effects of the two electrodes, such asymmetric cell exhibits superior electrochemical performances. An optimized asymmetric supercapacitor can be cycled reversibly in the voltage range of 0–1.8 V, and exhibits maximum energy density of 51.1 Wh kg−1, which is much higher than that of MnO2//DWNT cell (29.1 Wh kg−1). Additionally, graphene/MnO2//ACN asymmetric supercapacitor exhibits excellent cycling durability, with 97% specific capacitance retained even after 1000 cycles. These encouraging results show great potential in developing energy storage devices with high energy and power densities for practical applications.
1,768 citations
TL;DR: In this article, the authors provide a description of the emerging biorefinery concept, in comparison with the current oil refinery, as well as discussion of the most important biomass feedstocks, conversion technologies and final products.
1,754 citations