Francisco C. Robles-Hernández

University of Houston | U of H, UH · Department of Engineering Technology

Protein rich culture media are employed in the production of lactic acid bacteria (LAB); however, production costs are high. In this work media formulation and evaluation for LAB production were conducted considering physiological properties of lactic acid bacteria. Consumption efficiency (E), yield production (Y) and specific substrate consumption...

Over the past decade, the alarming rise in antibiotic resistance and adverse drug reactions has spurred intense research efforts to uncover innovative antimicrobial agents. In this comprehensive study, our primary goal was to unravel the intricate chemical composition of the essential oil, hexane, alcoholic, and aqueous extracts from Brassica olera...

All-solid-state batteries with lithium metal anodes hold great potential for high-energy battery applications. However, forming and maintaining stable solid-solid contact between the lithium anode and solid electrolyte remains a major challenge. One promising solution is the use of a silver-carbon (Ag-C) interlayer, but its chemomechanical properti...

Atmospheric pressure microwave plasma has the lead in synthesizing freestanding and scalable graphene within seconds without the need for high vacuum and temperature. However, the process is limited in utilizing chemical sources for synthesis, such as methane and ethanol. Herein, the usage of an extract of a sustainable precursor, that is, Melaleuc...

Modifiers are commonly used in natural, biological, and synthetic crystallization to tailor the growth of diverse materials. Here, we identify tautomers as a new class of modifiers where the dynamic interconversion between solute and its corresponding tautomer(s) produces native crystal growth inhibitors. The macroscopic and microscopic effects imp...

Modifying and functionalizing activated carbon using metal nanoparticles have received great scientific attention in recent decades as a method to improve its inherent properties. The synergistic effects between the dopant and the activated carbon could lead to advanced properties in the hybrid material compared to individual counterparts. In this...

Electrocatalysts with high activity and stability for hydrogen generation from water have become the increasing demand of future energy system. Despite all the advances in the synthesis of transition metal selenide nanostructures, the fabrication of two-dimensional (2D) electrocatalyst remains a major challenge. Here, a unique 2D FeSe2/CoSe nanoshe...

Continuous device downsizing and circuit complexity have motivated atomic-scale tuning of memristors. Herein, we report atomically tunable Pd/M1/M2/Al ultrathin (<2.5 nm M1/M2 bilayer oxide thickness) memristors using in vacuo atomic layer deposition by controlled insertion of MgO atomic layers into pristine Al2O3 atomic layer stacks guided by theo...

A ubiquitous phenomenon in zeolite synthesis is the generation of polymorphs leading to either single or multi-phase products. The use of organic structure-directing agents (OSDAs) often ensures a high degree of phase purity for a desired zeolite; however, OSDAs can be economically and environmentally prohibitive. The use of alkali metals as inorga...

Here we demonstrate the potential for solar-to-heat conversion of carbon byproducts and their outstanding effects to reduce anthropogenic emissions. Those carbon byproducts are soots (biomass, evaporated carbon, etc.) as well as morphed graphenes. Our results cover optical characterization to demonstrate their suitability as heat capacitors and sol...

In a time where global agricultural stability is facing unprecedented challenges due to growing population, climate change, and emerging pandemics, the development of advanced organic-inorganic functional nanohybrids as advanced fertilizers could contribute significantly to meeting these challenges. They hold the potential of reducing overall ferti...

In this work we report the bandgap tuning of pseudoboehmite achieved by high energy ball milling. The milling process of pseudoboehmite was performed using a SPEX 8000 mill for of up to 10 h. Pseudooehmite powders were characterized before and after milling by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectrosc...

In this paper, we present the design of an effective pulse current deposition process for low stress, crack-free Cr coatings deposited from standard Cr ³⁺ electrolyte commonly used by industry. Parameters for pulse current deposition process such as t on , t off , and duty cycle are based on detailed analysis and modeling of in situ stress transien...

The integration of highly luminescent CsPbBr3 quantum dots on nanowire waveguides has enormous potential applications in nanophotonics, optical sensing, and quantum communications. On the other hand, CsPb2Br5 nanowires have also attracted a lot of attention due to their unique water stability and controversial luminescent property. Here, the growth...

Supercapacitors will serve as essential components of distributed energy storage networks and structural power devices in many emerging technologies. Current supercapacitors are engineered, however, using ‘sandwich’ architecture that undermines their physical integrity under stress and at high temperatures due to delamination. It also limits the su...

The chemical synthesis of monoatomic metallic copper is unfavorable and requires inert or reductive conditions and the use of toxic reagents. Here, we report the environmental extraction and conversion of CuSO4 ions into single-atom zero-valent copper (Cu0) by a copper-resistant bacterium isolated from a copper mine in Brazil. Furthermore, the bios...

Synthesis of ultrathin heterostructures has received much attention in the recent past due to their unique physical and chemical properties. In this work, we report the synthesis of Fe2TiO5-TiO2 heterostructures using a simple hydrothermal technique employing natural ilmenite as the source. Hierarchically arranged nanostructures with interconnected...

Studies on intercalation or substitution of atoms into layered two-dimensional (2D) materials are rapidly expanding and gaining significant consideration due to their importance in electronics, catalysts, batteries, sensors, etc. In this manuscript, we report a straightforward method to create a Sulphur (S) deficient Molybdenum (Mo) sulfide (MoS2-x...

We report on a feasibility study of using Raman micro-spectroscopy as a characterization method for quality control of REB a 2 C u 3 O 7 − δ (REBCO, rare-earth barium copper oxide) coated conductors (CC). Fragments of long REBCO tape deposited using advanced metal organic chemical vapor deposition with dropouts in critical current ( I c ) were anal...

Synthesis of hybrid drug molecules from naturallyoccurring organic compounds has potential applications in severalfields, including theranostics. In this work, we report the extraction ofplumbagin from the roots ofPlumbago indicaL. and used it as aprecursor to prepare plumbagin-functionalized magnetite nanoparticles(PFMNPs). The derived PFMNPs were...

Graphene is a promising material for many biointerface applications in engineering, medical, and life-science domains. Here, we explore the protection ability of graphene atomic layers to metals exposed to aggressive sulfate-reducing bacteria implicated in corrosion. Although the graphene layers on copper (Cu) surfaces did not prevent the bacterial...

In this study, self-standing and flexible Li-ion battery negative electrodes made of interconnected two-dimensional carbonized cotton fibers are developed by using a controlled pyrolysis method, and their electrochemical performance in laboratory-scale lithium-based cells is investigated at ambient temperature. By applying this binder- and current...

The discovery of ferromagnetism in atomically thin layers at room temperature widens the prospects of 2D materials for device applications. Recently, two independent experiments demonstrated magnetic ordering in two dissimilar 2D systems, CrI3 and Cr2Ge2Te6, at low temperatures and in VSe2 at room temperature, but observation of intrinsic room‐temp...

Two-dimensional (2D) magnetism has been highly sought after since the discovery of graphene, the first and most studied of all the 2D materials. However, experimental evidence for ferromagnetic ordering in isotropic 2D crystals has been missing until a three-atoms thick CrI3 was shown to retain ferromagnetic ordering at finite temperatures down to...

The photocatalytic solar water splitting with Pt loaded graphitic carbon nitride (g-C3N4) and without sacrificial reagent is still a big challenge. In this work, g-C3N4 nanosheets were exfoliated for the first time by a femtosecond pulsed laser. After loaded with 1.4 wt.% of Pt, g-C3N4 becomes active towards the overall water splitting with a produ...

Present work explores graphene-coated vanadium pentoxide (G-V2O5) as novel electrosorption material for the desalination of low molarity saline/brackish water. During the desalination cycles, along with the electrical double layer formation at the graphene layer, ion intercalation is observed in the honeycomb structure of the hydrothermally grown V...

Lithium-sulfur batteries have shown great promise as next-generation high energy density power sources, but their commercial applications are hindered by short cycle life arising from the dissolution and shuttling of polysulfides. To address this shortcoming, we prepared two types of semi-hollow core-shell nanoparticles in which (1) elemental sulfu...

In the present study, we proposed an eco-friendly method to produce exfoliated graphite based on a dry mechanochemical process. This route represents an alternative that avoids the use and disposal problems related to highly corrosive and dangerous reagents use, manipulation and elimination. As non-toxic alternative exfoliation route, an equimolar...

Low Dose Electron MIcroscopy of Amonium Urates - Hector Calderon, Jeffrey Rimer, Francisco Robles-Hernandez, Christian Kisielowski

Mill Processing in Three Different Devices; The Effect of Intrinsic Intensity on the Material - G. Tarango-Rivero, J.M. Mendoza-Duarte, Francisco Robles-Hernandez, C.D. Gómez-Esparza, Caleb Carreño-Gallardo, C.G. Garay-Reyes, Ivanovich Estrada, R. Martínez-Sánchez

Fullerene Carbon Soot Characterization for Application as a New Solar Energy Absorption Material - Luis Bernardo López-Sosa, Francisco Robles-Hernandez, Mauricio González-Avilés, Ismael Santos-Ramos, J. Zárate-Medina, Luis Mariano Hernández-Ramírez, Ariosto Medina-Flores

This paper reports the synthesis and study of doped metal oxides as the shell in core-shell nanoparticle architectures. Specifically, the manuscript describes the synthesis of gold nanoparticles (Au NPs) and gold-silver nanoshells (GS-NSs) coated with antimony-doped and zinc-doped tin oxide shells (i.e., [email protected], [email protected], [email...

We present the antimicrobial properties of CoO-TiO2 tested against Listeria monocytogenes (L. monocytogenes), a harmful foodborne pathogenic microorganism. In this study we characterized the interaction of L. monocytogenes and CoO-TiO2 and identified the efficacy of CoO-TiO2 against L. monocytogenes using viability assays. The results show that CoO...

Graphene and its derivatives have acquired substantial research attention in recent years due to a wide range of potential applications. Implementing sustainable technologies for fabricating these functional nanomateri-als is becoming increasingly apparent, and therefore a wide spectrum of naturally derived precursors have been identified and refor...

The observation of low energy edge photoluminescence and its beneficial effect on the solar cell efficiency of Ruddlesden-Popper perovskites has unleashed an intensive research effort to reveal its origin. This effort, however, has been met with more challenges as the underlying material structure has still not been identified; new modellings and o...

With the rising cost and insufficient supply of cobalt, the thrust for cobalt-free cathode materials with the high specific capacity to build Li-ion batteries has increased significantly. Using nickel as the prime electrochemical active species, we have synthesized a new-class of materials with the combination of ordered and disordered phases. To o...

Here is described an effective form to degrade paraoxon using titanium dioxide (TiO2) doped with various metals (Al, C, Co, Fe, and Rh). The degradation of paraoxon was conducted under sunlight or assisted by a commercial light bulb. The synthesis of the TiO2 was conducted by sonochemical means. The heat treatment conditions were carefully manipula...

Chitosan is a natural-occurring biopolymer found commonly in the exoskeleton of crustaceans, vegetables, fungi and plants. Due to its relatively high mechanical properties, chitosan, is attractive for structural applications. Here, we show the benefits of morphed graphene as reinforcement for chitosan composites. Morphed graphene is incorporated in...

The presented work investigates the pulse current deposition as an approach for electrodeposition of functional Cr films. Our data suggest that observed growth stress during DC Cr deposition are negative, i.e. compressive with steady state values in the range below -100 MPa. The negative stress is associated with blistering in Cr films and accumula...

Mechanical Synthesis of Fullerene-Graphene/Morphed Graphene Architectures - Volume 25 Supplement - Hector A. Calderon, Omar Velazques Meraz, Luis Echegoyen, Francisco C. Robles Hernandez

Electron Microscopy of Sulfur Selenium Alloy with High –K Dielectric Properties. - Volume 25 Supplement - Hector A. Calderon, Francisco C. Robles Hernandez, Pulickel M. Ajayan

Atomic Resolution Characterization of Cr Thin Films Produced from Cr3+ Electrolytes - Volume 25 Supplement - Francisco C. Robles Hernandez, Kamyar Ahmadi, Adam Stokes, Jace McNeil, Stanko R. Brankovic

Low Dose TEM on the Degradation of the MAPbI3 Perovskite - Volume 25 Supplement - Hector A Calderon, Jiming Bao, Yanan Wang, Viktor Hadjiev, Francisco C. Robles Hernandez

The design of new and improved catalysts is an exciting field and are being constantly improved for development of economical, highly efficient material and as well for possible replacement of platinum (Pt) based catalysts. In this, carbon-based materials play a pivotal role due to their easy availability and environmental friendliness. Herein, we...

We present the properties of a photo-catalytically activated CoTiO3 framework supported on TiO2 (rutile). To demonstrate the effectiveness of this TiO2–CoTiO3 compound under light illumination, we tested its degradation potential against acid orange 7 dye. The dye degradation is effective over a wide range of laser excitation wavelengths from 1064...

We present the mechanical properties of all-carbon composites reinforced with in situ incorporated morphed graphene nanostructures by means of high energy ball milling and spark plasma sintering. The composites demonstrate enhanced elasticity for carbon sp³/sp² ratio ≈1/4. High resolution TEM characterization and molecular dynamics simulations show...

Since the first report of the green emission of 2D all‐inorganic CsPb2Br5, its bandgap and photoluminescence (PL) origin have generated intense debate and remained controversial. After the discovery that PL centers occupy only specific morphological structures in CsPb2Br5, a two‐step highly sensitive and noninvasive optical technique is employed to...

Sodium silicate has a wide range of applications such as adhesives, lower carbon cements, cleaning compounds, deflocculants, protective coatings, soaps and detergents, silica-type catalysts and gels, and pigments. It is mainly obtained as a liquid, but a small fraction can be found in solid state. In this work, three different synthesis methods to...

Upcoming advancements in flexible technology require mechanically compliant dielectric materials. Current dielectrics have either high dielectric constant, K (e.g., metal oxides) or good flexibility (e.g., polymers). Here, we achieve a golden mean of these properties and obtain a lightweight, viscoelastic, high-K dielectric material by combining tw...

Zeolite crystals can be used as seeds or aluminosilicate sources in syntheses to control polymorphs and/or reduce the quantity of organics used as structure‐directing agents. A frequently invoked hypothesis for interzeolite transformations is that zeolites share some underlying similarity in structure, most notably in cases pertaining to organic‐fr...

In this work we present a unique method to synthesize χ‐Al2O3 and α‐Al2O3 doped with Cr³⁺ (ruby). The ruby is synthesized by mechanical milling of pseudoboehmite that is doped in‐situ with chromium. The doping is carried by adding chromium sulfate hydrate to an aqueous solution rich in aluminum sulfate hydrate. The pH in the solution is controlled...