Jorge Colón

Universidad de Puerto Rico, Rio Piedras, Chemistry, Faculty Member

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Professor of Inorganic Chemistry at the University of Puerto Rico, Río Piedras Campus. I'm a Physical Inorganic Chemist and my research interests are solar energy and solar fuels, artificial photosynthesis, electrocatalysis, biosensors, and drug delivery using layered inorganic nanoparticles. I'm PI of the NSF-PREM Center for Interfacial Electrochemistry of Energy Materials (CIE2M http://prem-cie2m.upr.edu). I'm also interested in outreach and have been giving workshops on solar energy through the Caribbean Brigade of the Solar Army.
Phone: +1 787-402-2015
Address: Department of Chemistry
University of Puerto Rico
17 Ave. Universidad STE 1701
San Juan, Puerto Rico 00925-2537

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Papers by Jorge Colón

Tailored Organic-Inorganic Materials

Wiley eBooks, Feb 27, 2015

ABSTRACT This book explores the limitless ability to design new materials by layering clay materi... more ABSTRACT This book explores the limitless ability to design new materials by layering clay materials within organic compounds. Assembly, properties, characterization, and current and potential applications are offered to inspire the development of novel materials. Coincides with the government&#39;s Materials Genome Initiative, to inspire the development of green, sustainable, robust materials that lead to efficient use of limited resources Contains a thorough introductory and chemical foundation before delving into techniques, characterization, and properties of these materials Applications in biocatalysis, drug delivery, and energy storage and recovery are discussed Presents a case for an often overlooked hybrid material: organic-clay materials

Layered Inorganic Materials as Redox Agents: Ferrocenium-Intercalated Zirconium Phosphate

by Mitkel B Santiago and Jorge Colón

Langmuir, 2007

The direct intercalation reaction of ferrocene (bis(eta5-cyclopentadienyl)iron(II), Fc) with a hi... more The direct intercalation reaction of ferrocene (bis(eta5-cyclopentadienyl)iron(II), Fc) with a highly hydrated layered zirconium phosphate (ZrP) resulted in the formation of the ferrocenium ion (Fc+) within the ZrP material. The Fc+-intercalated ZrP material has an interlayer distance of 10.7 A. The intercalated material was used as an electron acceptor for the oxidation of both ferro-cytochrome c and the excited state of tris(2,2&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-bipyridine)ruthenium(II) ([Ru(bpy)3]2+). Upon contact of the material with a 1.5 x 10(-5) M solution of ferro-cytochrome c, the UV-vis absorption spectrum shows the successful formation of ferri-cytochrome c. Luminescence spectroscopy shows that the Fc+-intercalated ZrP material quenches the luminescence of [Ru(bpy)3]2+. The excited-state quenching mechanism of [Ru(bpy)3]2+* by Fc+-intercalated ZrP follows a dynamic plus sphere of action model. The second-order dynamic quenching rate constant kq is 2.2 x 10(8) M(-1) s(-1).

Effect of Enzyme and Cofactor Immobilization on the Response of Ethanol Oxidation in Zirconium Phosphate Modified Biosensors

by Mitkel B Santiago and Jorge Colón

Electroanalysis, 2010

Two different self-contained ethanol amperometric biosensors incorporating layered [Ru(phend) 2 b... more Two different self-contained ethanol amperometric biosensors incorporating layered [Ru(phend) 2 bpy] 2þ-intercalated zirconium phosphate (ZrP) as the mediator as well as yeast-alcohol dehydrogenase (y-ADH) and its cofactor nicotinamide adenine dinucleotide (NAD þ) were constructed to improve upon a design previously reported where only this mediator was immobilized in the surface of a modified electrode. In the first biosensor, a [Ru(phend) 2 bpy] 2þintercalated ZrP modified carbon paste electrode (CPE) was improved by immobilizing in its surface both y-ADH and NAD þ using quaternized Nafion membrane. In the second biosensor, a glassy carbon electrode was modified with [Ru(phend) 2 bpy] 2þ-intercalated ZrP, y-ADH, and NAD þ using Nafion as the holding matrix. Calibration plots for ethanol sensing were constructed in the presence and absence of ZrP. In the absence of ZrP in the surface of the modified glassy carbon electrode, leaching of ADH was observed as detected by UV-vis spectrophotometry. Ethanol sensing was also tested in the presence and absence of ascorbate to measure the selectivity of the sensor for ethanol. These two ethanol biosensors were compared to a previously reported one where the y-ADH and the NAD þ were in solution, not immobilized.

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Earth abundant electrocatalysts for the oxygen evolution reaction of water splitting using nanostructured layered inorganic nanomaterials

Preparation of Zirconium Phosphate Nanomaterials and Their Applications as Inorganic Supports for the Oxygen Evolution Reaction

Nanomaterials, Apr 26, 2020

Zirconium phosphate (ZrP) nanomaterials have been studied extensively ever since the preparation ... more Zirconium phosphate (ZrP) nanomaterials have been studied extensively ever since the preparation of the first crystalline form was reported in 1964. ZrP and its derivatives, because of their versatility, have found applications in several fields. Herein, we provide an overview of some advancements made in the preparation of ZrP nanomaterials, including exfoliation and morphology control of the nanoparticles. We also provide an overview of the advancements made with ZrP as an inorganic support for the electrocatalysis of the oxygen evolution reaction (OER). Emphasis is made on how the preparation of the ZrP electrocatalysts affects the activity of the OER.

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Intercalation of rhenium bipyridine complexes with zirconium phosphate nanoparticles for energy-related reactions

Abstracts of Papers of The American Chemical Society, 2018

Systematic Preparation Of Polyoxometalate Pillared Layered Double Hydroxides Via Direct Aqueous Reaction

MRS Proceedings, 1991

The series of layered double hydroxides, MgnAI(OH)2n+2X (n = 2-5, X = N0 3 " or Cl') and NinAl(OH... more The series of layered double hydroxides, MgnAI(OH)2n+2X (n = 2-5, X = N0 3 " or Cl') and NinAl(OH) 2 n+ 2 X (n = 2-4, X = NO3-or Cl-), were pillared with polyoxometalate ions of the Keggin structure, ranging from [PW 1 20 4 0] 3-to [PV 4 W 8 0 40 ] 7 ", in aqueous solution. Full exchange of the Keggin ions into the layers is achieved as evidenced by X-ray powder diffraction, infrared spectroscopy, elemental analysis and thermogravimetric analysis. Also, partial exchange was observed for Ni 5 Al(OH) 12 NO 3. The key factor that effects these reactions is the pre-swelling step. Thus, when the layered double hydroxides are thoroughly wet either by preparing wet solids or by soaking the dried products for an extended period, pillaring reactions proceed with great ease. Relations can be extracted between the water content and the separation between the layers, as well as between layer charge density and the charge of the Keggin ion. The pillared layered double hydroxides were found generally to have interlayer distances ranging from 11.0 to 13.5 A, which is smaller than the numerical sum of the Keggin ion diameter and the ideal thickness of the hydroxide layer. This fact and the low crystallinity are attributed to strong interaction between the basic layered double hydroxides and the acidic Keggin ions. A more crystalline phase with the expected 14.5 A interlayer spacing was also obtained as a mixture with the lower spaced products.

$X-ray powder diffraction (XRD) pattern for a thin film of Mg2Al(OH)¢6(PV3W9Oa0), /e+ Tuumbers referring to the d-spacing values in A.$

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Transition Metal-Modified Exfoliated Zirconium Phosphate as an Electrocatalyst for the Oxygen Evolution Reaction

ACS applied energy materials, Apr 19, 2019

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Electron transfer in ruthenium/zinc porphyrin derivatives of recombinant human myoglobins. Analysis of tunneling pathways in myoglobin and cytochrome c

Journal of the American Chemical Society, Feb 1, 1993

Site-directed mutants of human myoglobin have been prepared and characterized; each protein has a... more Site-directed mutants of human myoglobin have been prepared and characterized; each protein has a single surface-modifiable histidine (at position 48, 70, or 83). The proteins were .modified by covalent attachment of pentaammineruthenium (a5Ru) to the surface histidine and substitution of zinc mesoporphyrin IX diacid (ZnP) for the heme. Donor-acceptor separations (edge-edge distances d) in the modified proteins are 9.5 A, His70; 12.7 A, His48; and 15.5 A, His83. Rates of photoinduced electron transfer in these ruthenium-modified myoglobins were measured by transient absorption spectroscopy. The 3ZnP*-Ru3+ rate constants are 1.6 X IO' (His'lO), 7.2 X lo4 (His48), and 4.0 X lo2 s-I (His83) (-AGO = 0.82 eV); charge-recombination (Ru2+-ZnP') rates are 1.1 X lo5 (His48) and 7.3 X lo2 s-I (His83) (-AGO = 0.96 eV). Activationless (maximum) rates assuming h = 1.3 eV are 7.2 X lo7 (His70), 3.3 X lo5 (His48). and 1.8 X lo3 s-l (His83). Distant electronic couplings, which limit the maximum rates in the modified myoglobins, have been analyzed along with data from Ru-modified cytochromes c in terms of a tunneling pathway model. Single dominant pathways adequately describe. the electronic couplings in cytochrome c but do not satisfactorily account for the myoglobin couplings. The correlation of electronic coupling with tunneling length for myoglobin is improved significantly by the inclusion of multiple pathways. reaction^.^-'^ If a simple homogeneous medium separates donor

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Zirconium phosphate supported electrocatalysts for the oxygen-evolution reaction

The Solar Army

Water Splitting Electrocatalysis within Layered Inorganic Nanomaterials

IntechOpen eBooks, Feb 5, 2020

The conversion of solar energy into chemical fuel is one of the "Holy Grails" of twenty-first cen... more The conversion of solar energy into chemical fuel is one of the "Holy Grails" of twenty-first century chemistry. Solar energy can be used to split water into oxygen and protons, which are then used to make hydrogen fuel. Nature is able to catalyze both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) required for the conversion of solar energy into chemical fuel through the employment of enzymes that are composed of inexpensive transition metals. Instead of using expensive catalysts such as platinum, cheaper alternatives (such as cobalt, iron, or nickel) would provide the opportunity to make solar energy competitive with fossil fuels. However, obtaining efficient catalysts based on earthabundant materials is still a daunting task. In this chapter, we review the advancements made with zirconium phosphate (ZrP) as a support for earth-abundant transition metals for the OER. Our studies have found that ZrP is a suitable support for transition metals as it provides an accessible surface where the OER can occur. Further findings have also shown that exfoliation of ZrP increases the availability of sites where active species can be adsorbed and performance is improved with this strategy.

$duce expanded phases) are commonly used as precursors to intercalate the intended guest species. One problem that arises with this method is that the pre-intercalated species do not necessarily exchange completely with the intended guest, thus becoming a contaminant in the intercalation product. Marti and Colon developed a new direct intercalation method that does not require a pre-intercalation step using a highly hydrated phase of zirconium phos- phate, 8-ZrP [27]. 0-ZrP maintains the a-ZrP-type layered structure (Figure 2) but has an interlayer distance of 10.4 A and has six water molecules per formula unit, in contrast with a-ZrP that only has one [28]. Zirconium bis(monohydrogen ortho- phosphate) hexahydrate (9-ZrP) converts back to a-ZrP when it dehydrates. X-ray powder diffraction (XRPD) can be used to distinguished between both ZrP phases. When 0-Z1P is dried, producing a-ZrP, the first diffraction peak at 20 = 8.6° which corresponds to the 002-plane reflection of ZrP and that of the interlayer distance, shifts towards 11.6°; the angle corresponding to an interlayer distance of 7.6 A, characteristic of a-ZrP (Figure 3). For this reason, if a dry intercalation product is analyzed by XRPD and the first diffraction peak corresponds to a distance greater than 76 A, this indicates that the intercalation reaction was successful [29]. One of three possible patterns can be observed by XRPD for intercalation products of ZrP; either (i) a pattern with a peak corresponding to a larger interlayer spacing at lower 20 values than 11.6° indicates that the intercalant was introduced into the interlayer, (ii) a pattern with two distinct peaks, one at 20 = 11.6° and one that appears at lower$

$Figure 5. (a) X XRPD patterns for Fe(II), Fe(III), Co(II), and Ni(II)-intercalated ZrP at (from top to bottom) 10:1, 5:1, 3:1, 1:1, 1:3, 1:5, 1:10, and 1:20 M:ZrP molar ratios. The bottom diffraction pattern in all frames is that of pure a-ZrP; (b) interlayer distance as a function of M:ZrP molar ratio for the various metal-intercalated ZrP materials. Metal-adsorbed systems ave represented as dashed lines which have an exact interlayer spacing as pure a-ZrP indicating that metal intercalation did not occur. Taken from reference [69]. aed eG SAA A OE SSN AN SAS SO Ve Pe RA CLA Wet hel | a ie nen ‘kal CA VSsitstw sd £441 VL because of a stronger electrostatic attraction between the metal cation and the negatively charged ZrP layers. Ion-exchange in ZrP occurs at the Bronsted acid groups (P-OH) which are also present at the surface of the nanoparticles. Hence, there is no way of preventing that the metal cations get adsorbed to the surface. To obtain more insights into the nature of the activity of the samples, a metal-modified ZrP system in which the metals are only adsorbed onto the surface of the nanoparticles was also prepared. To prepare these samples, a-ZrP must be used as the ZrP source as the metal cations are large enough to not intercalate into the interlayer. XRPD data shows that the interlayer distance of these dry sample remains that of a-ZrP, 7.6 A (Figure 5b). The presence of the metals in these systems was confirmed by high resolution X-ray photoelectron spectroscopy (XPS). XPS was also used to determine the atomic concentration on both metal-modified ZrP systems, intercalated and adsorbed [69]. Due to the uptake of metal cations within the much larger area of the interlayers of ZrP rather than solely on the surface in the adsorbed case, XPS high resolution scans show that intercalated ZrP systems have higher atomic metal content when compared to adsorbed systems at similar M:ZrP ratios. eT i, ny ee or i ce i, ee ee 2$

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Puerto Rico's future at stake

Science, Sep 11, 2015

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