Jennifer D Lee

Jennifer D Lee
University of Pennsylvania | UP · Department of Chemistry

Doctor of Philosophy

About

34
Publications
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793
Citations

Publications

Publications (34)
Article
Hydrodeoxygenation (HDO) of 5-hydroxymethylfurfural (HMF) was examined over well-defined and uniform, Pt-Ni, Pt-Zn and Pt-Cu alloyed nanocrystals (NCs) supported on carbon, at 33 bar and between 160 and 200 °C. Pt-Ni alloy catalysts were prepared in three different Pt:Ni ratios, Pt6Ni, Pt3Ni, and PtNi. While all of the Pt-Ni alloys were more select...
Article
The collective magnetic properties of nanoparticle (NP) solid films are greatly affected by inter-particle dipole-dipole interactions and therefore proximity of the neighboring particles. In this study, a series of dendritic ligands (generations 0 to 3, G0-G3), has been designed and used to cover the surface of magnetic NPs to control the spacings...
Article
The design of selective and active heterogeneous catalysts for the hydrodeoxygenation (HDO) of biomass-derived platform molecules requires understanding of the catalyst structure under reaction conditions. In this work, we design, build and qualify an operando X-ray absorption (XAS) cell to characterize a highly selective NiCu3 catalyst under HDO c...
Article
The development of a suitable catalyst for the oxygen reduction reaction (ORR) – the cathode reaction of proton exchange membrane fuel cells (PEMFC) – is necessary to push this technology towards widespread adoption. There have been substantial efforts to utilize bimetallic Pt-M alloys that adopt the ordered face-centered tetragonal (L10) phase in...
Article
Hydrodeoxygenation (HDO) of 2-acetylfuran (2-AF) was examined at 473 K and 33 bar over carbon-supported, bimetallic catalysts. Monodispersed, Pt-based (PtNi, PtCo, and PtCu) and Ni-based (NiCu) nanocrystals (NCs) with well-defined sizes and compositions were prepared via colloidal synthesis. Steady-state, flow-reactor measurements demonstrate that...
Preprint
The dissociation of H2 is an essential elementary step in many industrial chemical transformations, typically requiring precious metals. Here, we report a hierarchical nanoporous Cu catalyst doped with small amounts of Ti (npTiCu) that increases the rate of H2-D2 exchange by approximately one order of magnitude compared to the undoped nanoporous Cu...
Article
The development of new catalyst materials for energy-efficient chemical synthesis is critical as over 80% of industrial processes rely on catalysts, with many of the most energy-intensive processes specifically using heterogeneous catalysis. Catalytic performance is a complex interplay of phenomena involving temperature, pressure, gas composition,...
Article
Platinum is the primary catalyst for many chemical reactions in the field of heterogeneous catalysis. However, platinum is both expensive and rare. Therefore, it is advantageous to combine Pt with another metal to reduce cost while also enhancing stability. To that end, Pt is often combined with Co to form Co-Pt nanocrystals. However, dynamical res...
Article
Full-text available
A novel approach for finding and evaluating structural models of small metallic nanoparticles is presented. Rather than fitting a single model with many degrees of freedom, libraries of clusters from multiple structural motifs are built algorithmically and individually refined against experimental pair distribution functions. Each cluster fit is hi...
Article
Full-text available
We report a generalized wet-chemical methodology for the synthesis of transition metal (M) doped brookite-phase TiO2 nanorods (NRs) with unprecedented wide-range tunability in dopant composition (M = V, Cr, Mn, Fe, Co, Ni, Cu, Mo, etc.). These quadrangular NRs can selectively expose {210} surface facets, which is induced by their strong affinity fo...
Article
The synthesis of colloidal III-V quantum dots (QDs), particularly of the arsenides and antimonides, has been limited by the lack of stable and available group V precursors. In this work, we exploit accessible InCl3- and pnictogen chloride-oleylamine as precursors to synthesize III-V QDs. Through coreduction reactions of the precursors, we achieve s...
Article
Substitutional doping is a potentially powerful technique to control the properties of nanocrystal (NC) superlattices (SL). However, not every NC can be substituted into any lattice, as the NCs have to be close in size and shape, limiting the application of substitutional doping. Here we show that this limitation can be overcome by employing ligand...
Article
In this study, the impact of supported Pt particles on the thermal and photocatalytic activity of well-defined anatase TiO2 (A-TiO2) nanocrystals (NCs) was investigated. Pt-decorated NCs were characterized using scanning transmission electron microscopy (STEM), energy dispersive x-ray spectroscopy (EDS), and x-ray photoelectron spectroscopy (XPS)....
Article
Colloidal semiconductor nanocrystals (NCs) are a promising materials class for solution-processable, next-generation electronic devices. However, most high-performance devices and circuits have been achieved using NCs containing toxic elements, which may limit their further device development. We fabricate high mobility CuInSe2 NC field-effect tran...
Preprint
Full-text available
We present a novel approach for finding and evaluating structural models of small metallic nanoparticles. Rather than fitting a single model with many degrees of freedom, the approach algorithmically builds libraries of nanoparticle clusters from multiple structural motifs, and individually fits them to experimental PDFs. Each cluster-fit is highly...
Article
The influence of adding Pt on the catalytic and photocatalytic activity of monodispersed brookite phase TiO2 (B-TiO2) nanorods (NRs) was investigated. Pt was deposited on the NRs by photo-deposition in solution and the Pt-modified NRs were characterized using XPS, STEM, and LEIS. The thermal and photocatalytic activity of the Pt-modified NRs were t...
Article
Nanoparticle (NP) stability is imperative for commercialization of nanotechnology. In this study, we compare the stability of Au NPs with surfaces functionalized with oleylamine, dodecanethiol, and two dendritic ligands of different generations. The dendrimer ligands provide a significant increase in the chemical stability of the Au NPs when analyz...
Article
Nanocrystal (NC) solids are an exciting class of materials, whose physical properties are tunable by choice of the NCs as well as the strength of the interparticle coupling. One can consider these NCs as “artificial atoms" in analogy to the formation of condensed matter from atoms. Akin to atomic doping, the doping of a semiconducting NC solid with...
Article
Full-text available
A series of ZrO2-supported WOx catalysts were prepared using atomic layer deposition (ALD) with W(CO)6, and were then compared to a WOx/ZrO2 catalyst prepared via conventional impregnation. The types of sites present in these samples were characterized using temperature-programmed desorption/thermogravimetric analysis (TPD-TGA) measurements with 2-...
Article
Full-text available
We report direct photocatalytic hydrogen evolution from sub-stoichiometric highly reduced tungsten oxide (WOx) nanowires (NWs) using sacrificial alcohol. WOx NWs are synthesized via non-aqueous colloidal synthesis with a diameter of about 4 nm and an average length of about 250nm. As-synthesized WOx NWs exhibit a broad absorption across the visible...
Article
Full-text available
The hydrogenolysis of tetrahydrofurfural alcohol to 1,5-pentanediol was studied over a series of carbon-supported metal/metal-oxide pairs. In agreement with previous reports, specific pairs, especially Pt and Ir paired with WOx, MoOx and ReOx, exhibited high activity and selectivity, even though the individual components were not active or selectiv...
Article
Rare-earth (RE) compounds have been actively pursued for therapeutic and diagnostic applications due to their ability to upconvert near infrared light into the UV–vis range. Through nanoengineering and bottom-up synthesis, additional functionality can be added to these upconverting systems. Herein, we report the synthesis of ⁹⁰Y-doped β-NaYF4:Er, Y...
Article
Controlling nanoparticles’ (NPs) surface polarity, colloidal stability, and self-assembly into well-defined complex architectures is of paramount importance for emergent nano- and biotechnologies, and each depends strongly on the ligand shell composition and chemical nature. In this study, a series of dendritic ligands with hydrophobic, hydrophilic...
Article
The hydrodeoxygenation (HDO) of furfural to 2-methylfuran (MF) was investigated in a continuous flow reactor over carbon-supported, PtCo3 nano-crystals (NCs) and NiFe bimetallic catalysts, along with their monometallic counterparts, at 1 and 33 bar, respectively. At 1 bar, the decarbonylation reaction to furan was a major non-selective pathway on b...
Article
The selective hydrodeoxygenation (HDO) of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF) is an important step in cellulosic biomass upgrading to biofuels, where bimetallic oxophilic catalysts have shown promising performance. Well controlled, bimetallic NiCu and NiCu3 nanocrystals supported on carbon are shown to give high yields and sele...
Article
Several DNA templates with the sequence 5'-T n TAACCCCTAACCCCT-3' (n=0, 15, 30, and 45) were used to prepare DNA template-silver nanoclusters (DNA-Ag NCs). The T n sequence acts as a recognition element for Hg²⁺, while the rest of the sequence acts as a template for DNA-Ag NCs. At pH 3.0, the fluorescence intensity of DNA-Ag NCs is enhanced by ATP,...
Article
Carbon-supported, Pt and PtCo nanocrystals (NCs) with controlled size and composition were synthesized and examined for hydrodeoxygenation (HDO) of 5-hydroxymethylfurfural (HMF). Experiments in a continuous flow reactor with 1-propanol solvent, at 120 to 160°C and 33 bar H2, demonstrated that reaction is sequential on both Pt and PtCo alloys, with...
Article
Oligonucleotide-templated Ag nanoclusters (DNA-Ag NCs) prepared from AgNO3 using an oligonucleotide (5'-TAACCCCTAACCCCT-3') as a template and NaBH4 as a reducing agent have been used for sensing of adenosine 5'-triphosphate (ATP). The fluorescence intensity and emission wavelength of DNA-Ag NCs are dependent on the pH value and ATP concentration. A...

Projects

Projects (2)
Project
Catalysts for biomass valorization
Project
Well defined nanomaterials for catalytic and photocatalytic applications