Our project focuses on Europium-doped Cerium Oxide nanotubes and their use as potential probes for bioimaging and optical sensors. Most CeO2 nanomaterials are not intrinsically fluorescent in the visible region, so these materials can be doped with rare earth ions that possess visible fluorescence. Rare earth ions that prefer the +3 oxidation state can be efficiently doped into CeO2 nanomaterials due to their similar ionic radii. Our research utilizes Europium (III) for doping, which is known for its red-orange emission and hypersensitive 5D0→7F2 transition. We choose a one-dimensional architecture for the target nanostructure because of its ideal geometry to interact with cells. A sacrificial template is employed, beginning with the synthesis of Zinc Oxide nanowires on an FTO substrate. After the nanowires are grown, a Europium (III) - Cerium (III) cycling process is performed to construct the nanotube, using the nanowire as a template.
The size and morphology of the nanotubes are measured using a Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The crystalline structure of the Europium-doped CeO2 nanotubes can be characterized using X-ray diffraction (XRD) to determine how varying Eu3+ concentration can change the XRD peaks. Their photoluminescence (PL) spectra are measured as a function of varying the percentage concentration of Eu3+. Light emission is compared as a function of dopant concentration by varying the Eu3+ concentration between 5%-15% to determine the concentration with the optimal fluorescence intensity. Ultimately, the desired characteristic fluorescence of the nanotubes enables their use in bioimaging and as optical sensors.

Every 65 seconds, someone is diagnosed with Alzheimer's disease, which is the seventh leading cause of death in the United States. A major barrier to potential therapeutics is the permeability of these molecules across the blood-brain barrier. We have developed small molecules with strong reactivity to combat the oxidative stress known to cause Alzheimer’s disease. However, the permeability is less than ideal. As a result, my goal is to produce a molecule that has enhanced permeability but retains the reactivity of the parent molecules. To achieve this, the BOILED-Egg model was used to assess different derivatives of our parent molecule, Py2N2. This model showed the differences in lipophilicity among different Py2N2 compounds and how they impact permeability into the blood-brain barrier and gastrointestinal tract. Background information on our parent molecule and its function regarding Alzheimer's development will be outlined to give a scope of what these compounds can target and how they function. Compounds with high lipophilicity reflected in the model will have schemes of synthetic synthesis for future directions.

The binding of the water-soluble porphyrin tetrasodium tetraphenylporphyrintetrasulfonate (TPPS) to bovine serum albumin (BSA) in aqueous media at room temperature can be explored for developing an analytical assay for PFAS (or “forever chemicals”) detection. Indeed, we determined that spectrophotometric detection of PFAS is optimized by exploiting competitive binding of PFAS and TPPS to BSA at pH 4.7. In this poster, we spectrophotometrically investigated BSA-TPPS binding at pH 3.0, 4.7, and 7.2. Specifically, TPPS concentration was maintained constant at 80 M in our experiments and BSA concentration was varied. Interestingly, while BSA-TPPS complexes are soluble at pH 7.2, they form insoluble precipitates in acidic conditions (pH 3.0 and 4.7) at low BSA concentration. Specifically, we find that solubility of TPPS exhibits a minimum as BSA concentration increases. We therefore developed a theoretical model that successfully describes the observed behavior of TPPS solubility. Spectrophotometric calibration curves for the determination of PFAS concentration were constructed using solutions with a sufficiently high BSA:TPPS molar ratio.

Salt-induced diffusiophoresis is the migration of a charged nanoparticle in water, induced by an imposed directional gradient of salt concentration. This transport phenomenon has emerged as a valuable tool for particle manipulation inside porous materials and microfluidics. Micelles are a common example of nanoparticles with the crucial ability of hosting small guest molecules. Thus, micelle diffusiophoresis is important in the manipulation of small molecules. Diffusiophoresis depends on the intrinsic ability of micelles to randomly move (diffuse) in water. In this poster, we report experimental micelle diffusion coefficients for the surfactant hexadecylpyridinium chloride (CPC) in the presence of aqueous NaCl and KCl. The electrical double layer theory was successfully employed to explain the effect of surfactant and salt concentrations on the observed micelle diffusion coefficient. These data were then used to characterize salt-induced diffusiophoresis of charged micelles.

Influence of a NiO Hole Transport Layer on Charge Separation in FTO|WO₃|BiVO₄ Photoanodes for TEMPO-Mediated Oxidation

Favor Igwilo, Texas Christian University, Class of 2026
Laboratory of Dr. Benjamin Sherman, PhD;
Department of Chemistry and Biochemistry

Efficient hole transport is critical for driving oxidative transformations in photoelectrochemical systems. In this study, we investigate multilayer FTO|WO₃|BiVO₄|NiO photoanodes for application in TEMPO-mediated oxidation of benzyl alcohol to benzaldehyde, an important chemical reaction used in industrial processes. The stable radical 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) enables selective alcohol oxidation under mild conditions and represents a more sustainable alternative to conventional stoichiometric oxidants that generate hazardous waste. Enhancing interfacial charge transport is essential to improve the viability of this photoelectrosynthetic process.
We hypothesize that nickel oxide (NiO), a p-type semiconductor, can function as an effective hole transport layer due to its favorable valence band alignment, hole mobility, abundance, and low cost relative to traditional materials such as titanium dioxide (TiO₂). A liquid phase deposition protocol was developed to fabricate uniform NiO thin films on fluorine-doped tin oxide substrates, which were subsequently integrated into FTO|WO₃|BiVO₄ substrates. The resulting multilayer photoanodes were evaluated to determine whether NiO enhances charge separation and hole extraction under various conditions.
Electrochemical characterization was performed using cyclic voltammetry to probe redox behavior and assess catalytic onset potentials, chronoamperometry to quantify steady-state photocurrent and operational stability, and electrochemical impedance spectroscopy to evaluate interfacial charge transfer resistance. Measurements were conducted under both dark and illuminated conditions, with and without TEMPO, in Tetrabutylammonium hexafluorophosphate (TBAPF6)in acetonitrile (ACN) solution. We anticipate that incorporation of NiO will reduce interfacial charge transfer resistance, increase photocurrent density in the presence of TEMPO, and improve kinetic parameters associated with benzyl alcohol oxidation.
Photocurrent densities of FTO–WO₃–BiVO₄ and FTO–WO₃–BiVO₄–NiO photoanodes were directly compared to quantify the effect of the NiO interlayer. Additionally, heterogeneous electron transfer rate constants (k₀) were determined under TEMPO-containing conditions to assess how the multilayer structure influences interfacial electron transfer kinetics.
This work establishes a working protocol for NiO liquid phase deposition and clarifies the role of NiO in enhancing TEMPO-mediated photoelectrosynthetic oxidation. These findings can later inform the design of cost-effective photoelectrode architectures for sustainable organic reactions.