Fernando Vallejos-Burgos

Fernando Vallejos-Burgos
Morgan Advanced Materials · Carbon Science Centre of Excellence

Dr. Chemical Engineering Science

About

38
Publications
196,311
Reads
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445
Citations
Additional affiliations
November 2018 - present
Morgan Advanced Materials
Position
  • Researcher
April 2013 - November 2018
Shinshu University
Position
  • PostDoc Position
January 2006 - January 2012
University of Concepción
Position
  • PhD Student

Publications

Publications (38)
Article
The efficient separation of hydrogen from methane and light hydrocarbons for clean energy applications remains a technical challenge in membrane science. To address this issue, we prepared a graphene-wrapped MFI (G-MFI) molecular-sieving membrane for the ultrafast separation of hydrogen from methane at a permeability reaching 5.8 × 106 barrers at a...
Article
Reactions of carbon and oxygen containing molecules, such as O2, NO, H2O and CO2, are ubiquitous on earth and the universe. Through ab initio calculations, we study the reactions of H2O and CO2 with small graphene clusters containing armchair edges, both H- and non-H terminated, and compare with studies of zigzag carbon edges interacting with oxyge...
Technical Report
Isotopes like these are extremely valuable for a wide variety of applications like medical imaging and radiopharmaceuticals. This is the case with 18O, which makes up only 0.2 percent of the oxygen on earth. But generating pure 18O is very expensive, driving up the costs of medical applications. New research reported in Nature Communications intro...
Article
Full-text available
Isotopes of heavier gases including carbon (13C/14C), nitrogen (13N), and oxygen (18O) are highly important because they can be substituted for naturally occurring atoms without significantly perturbing the biochemical properties of the radiolabelled parent molecules. These labelled molecules are employed in clinical radiopharmaceuticals, in studie...
Preprint
Full-text available
This article was renamed after peer-review as: Oyarzún-Aravena, A.M., Gottschalk-Ojeda, C., Moya-Barría, I., and Vallejos-Burgos, F., Edge type effect in the gasification mechanism of graphene clusters with H2O and/or CO2: armchair vs. zigzag. Carbon, 2022. 193: p. 412-427. https://doi.org/10.1016/j.carbon.2022.02.048
Article
Full-text available
The Ar (87.3 K) and N2 (77.4 K) adsorption isotherms of six non-graphitized carbon blacks are compared to choose the best reference material for an accurate determination of surface area of porous carbons with subtracting pore effect (SPE) method using high resolution αs-plot. Microporous carbon blacks cannot be used as references for SPE method si...
Article
We report a route for opening nanowindows on graphene wall of single wall carbon nanohorn (SWCNH) aided by copper (II) 2,3,9,10,16,17,23,24-octakis (octyloxy)-29H, 31H-phthalocyanine (CuPc), which acts as a catalyst for nanowindow formation. CuPc is adsorbed on SWCNH from liquid phase and heat treated in oxygen atmosphere to produce nanowindows on...
Article
The fractional filling dependence of corrected diffusivity of H2O and D2O confined in activated carbon fiber (ACF) determined using newly developed pressure-feedback analysis clearly shows that the adsorption kinetics of H2O and D2O on ACF are governed by cluster growth associated with molecular hopping and cluster-aggregation. The isotope effect p...
Article
We fabricated mesoscopic cage-like structured Single-Wall Carbon Nanotube (SWCNT) cryogels having ultramicroporous necks using highly concentrated SWCNT-water inks with the aid of Zn–Al sol-gel dispersant. High-resolution transmission electron microscopy (TEM) image shows the presence of three-dimensional cage-like structures in the SWCNT cryogels,...
Preprint
Full-text available
Monitoring structural integrity during and after extreme events such as an earthquake or a tsunami is a mundane yet important task that still awaits a workable solution. Currently available stress sensors are not sufficiently robust and are affected by humidity. Insufficient information about crack formation preceding structural failure increases r...
Article
Monitoring structural integrity during and after extreme events such as an earthquake or a tsunami is a mundane yet important task that still awaits a workable solution. Additionally, the mechanical frame strength of transportation must be continuously monitored for sufficient safety. Currently available sensors are not sufficiently robust and are...
Article
Full-text available
Monitoring structural integrity during and after extreme events such as an earthquake or a tsunami is a mundane yet important task that still awaits a workable solution. Additionally, the mechanical frame strength of transportation must be continuously monitored for sufficient safety. Currently available sensors are not sufficiently robust and are...
Article
Full-text available
We revisit the quasi-equilibrium adsorption method as an inexpensive alternative to commercial volumetric apparatus for the measurement of gas adsorption isotherms. This method is based on how the pressure of a manifold containing the sample increases as a function of time when an adsorbing gas is introduced. We show that, under certain conditions,...
Chapter
Full-text available
Understanding of the explicit difference between supercritical gas and vapor is necessary for a better design of nanoporous materials for gas storage; we show the difference between supercritical gas and vapor with the van der Waals equation which leads to the critical point and the second virial coefficient. Detailed explanation on intermolecular...
Chapter
Full-text available
Understanding of the explicit difference between supercritical gas and vapor is requested for better design of nanoporous materials for gas storage, we show the difference between supercritical gas and vapor with the van der Waals equation which leads to the critical point and the second virial coefficient. Detailed explanation on intermolecular in...
Chapter
Full-text available
High pressure adsorption measurement of supercritical gas needs accurate particle density which should be obtained by high pressure He buoyancy measurement. As the surface excess mass adsorption is not greatly larger than the bulk gas contribution in the adsorbed layer, the absolute adsorption amount containing the bulk gas contribution in the adso...
Article
Electrically-conductive graphene colloids with tuned nanoporosity are promising materials for numerous applications. As charge-transfer interaction enhances electrical conductivity of polyaromatic hydrocarbon crystals, we intercalated water-soluble pyrene derivatives such as pyrene-boronic acid in nanoporous graphene by reduction of a mixture of gr...
Article
Full-text available
Nanoscale windows in graphene (nanowindows) have the ability to switch between open and closed states, allowing them to become selective, fast, and energy-efficient membranes for molecular separations. These special pores, or nanowindows, are not electrically neutral due to passivation of the carbon edges under ambient conditions, becoming flexible...
Article
Fabrication of nanographene can show a promising route for production of designed porous carbons, which is indispensable for high-efficient molecular separation and energy storage applications. This process requires a better understanding of the mechanical properties of nanographene in their aggregated structure. We study the structural and mechani...
Article
The detonation nanodiamonds form the aggregate having interparticle voids, giving a marked hygroscopic property. As the relationship between pore structure and water adsorption of aggregated nanodiamonds is not well understood yet, adsorption isotherms of N2 at 77 K and of water vapor at 298 K of the well-characterized aggregated nanodiamonds were...
Article
Carbide-derived carbons (CDCs) are nanoporous carbons with a tunable pore size, making them desirable for their adsorption properties. Despite their applicability, reliable structural models are difficult to construct due to the interplay between strong short-range order and long-range disorder. Here, a mimetic methodology is developed to generate...
Conference Paper
Full-text available
The special behavior of graphene nanowindows will be discussed mainly based on molecular dynamics simulations. We show that in order to understand permeation through a graphene framework, the framework motion, its electrostatic field and functional groups dihedral rotations need to be taken into account in the simulation.
Article
Rapidly growing research on biomass reactivity has not benefited enough from the very abundant knowledge acquired on coal-derived materials. Literature comparisons using similar methods are scant and inconclusive. To clarify differences (or similarities) between coal- and biomass-derived chars, we performed a systematic study using three different...
Article
High surface area graphene monoliths consist mainly of single graphene layers wider than 10 nm. The interlayer porosity of high temperature treated nanoporous graphene monoliths with tuned intergraphene layer structures is evaluated by hybrid analysis of Ar adsorption at 87 K, N2 adsorption at 77 K, high resolution transmission electron microscopic...
Article
Full-text available
We have developed a laser-induced chemical vapor deposition (LCVD) method for preparing nanocarbons with the aid of SF6. This method would offer advantages for the production of aggregates of nanoscale foams (nanofoams) at high rates. Pyrolysis of the as-grown nanofoams induced the high surface area (1120 m2 g 1) and significantly enhanced the adso...
Conference Paper
Full-text available
Low temperature flow of a multicomponent gas in a porous sample (dynamic multimolecular probe adsorption), allowed for quick determination of the extent of nanowindow opening, its size and adsorbed molecular distribution in samples of single wall carbon nanohorns (SWCNH) opened at different extents. Two different methods were employed for this purp...
Conference Paper
Full-text available
Flow of a multicomponent gas in a porous sample near condensation temperature (dynamic multimolecular probe adsorption), allowed for quick determination of the extent of pore opening, nanowindow size and adsorbed molecular distribution; this method was used to study the textural properties of single wall carbon nanohorns (SWCNH) oxidized at differe...
Article
Full-text available
Deposited and heat-treated phthalocyanines are promising electrocatalysts for replacing platinum in the oxygen reduction reaction (ORR), the most important process in energy conversion systems such as fuel cells; and yet its key mechanistic features are not well understood. To optimize their use, it is necessary to understand their behavior in the...
Article
Alumina supported cobalt (Co) catalysts are the preferred choice for Fischer-Tropsch synthesis (FTS) when using natural gas as raw material, which is the case of Qatar. It is thus of economical interest to find ways of increasing activity and/or selectivity of these catalysts. One way of modifying catalytic activity, consists of transformation of t...
Article
It is now a widely accepted fact that oxidized graphene surfaces are populated, to a greater or lesser extent, with epoxide groups. And yet the origin of these groups has heretofore been mysterious. We report the results of a computational (DFT) analysis of this issue carried out by combining the theoretical and experimental knowledge of three seem...
Article
Thermodynamic affinities, activation energies and diffusion coefficients for oxygen mobility on the graphene surface are calculated using density functional theory (DFT). We report and discuss the effects of geometry, charge distribution and heteroatom substitution on the migration of epoxy oxygen on the basal plane: both the driving force and the...
Article
Relatively inexpensive heterogeneous catalysts for two reactions of great importance in air pollution control, NO reduction and VOC combustion, were prepared and characterized. Apart from their common practical goal and the frequent need for simultaneous removal of air pollutants, these reactions share a similar redox mechanism, in which the formul...

Questions

Questions (3)

Projects

Projects (3)
Project
The project studies the reactivity of graphene sheets. Two main subtopics: a) Special effects seen at the edge of graphene layers and b) gas-graphene reaction (including NO, O2, H2O and CO2). This is done through computational chemistry. ---------------------------------------------------------------------------------------------------------------- Se pretende implementar computadores de alto rendimiento (HPC) para desarrollar investigación teórica sobre reacciones de combustión. Este proyecto fue ideado a partir de interrogantes surgidas en el trabajo de tesis de la investigadora principal y busca contestar preguntas fundamentales referentes a dos temas específicos: (a) efectos particulares observados ante la saturación de los bordes de grafeno y (b) el mecanismo de reacción de los NO con los bordes de la molécula de grafeno.
Project
I am striving to understand the role of a graphene nanowindow rim in molecular separations, when using a graphene layer as a membrane.