Doctor of Philosophy, University of Illinois Chicago (2021)
Bachelor of Science, University of Belgrade (2013)
Master of Science, Bowling Green State University (2017)
BSc, University of Belgrade (Serbia), Chemistry (2013)
MSc, Bowling Green State University, Photochemistry (2017)
PhD, University of Illinois at Chicago, Chemistry (2021)
Kelly Gaffney, Postdoctoral Faculty Sponsor
- Strong Electronic Coupling of Graphene Nanoribbons onto Basal Plane of a Glassy Carbon Electrode ACS APPLIED ELECTRONIC MATERIALS 2021; 3 (2): 854-860
Toward a mechanistic understanding of electrocatalytic nanocarbon.
2021; 12 (1): 3288
Electrocatalytic nanocarbon (EN) is a class of material receiving intense interest as a potential replacement for expensive, metal-based electrocatalysts for energy conversion and chemical production applications. The further development of EN will require an intricate knowledge of its catalytic behaviors, however, the true nature of their electrocatalytic activity remains elusive. This review highlights work that contributed valuable knowledge in the elucidation of EN catalytic mechanisms. Experimental evidence from spectroscopic studies and well-defined molecular models, along with the survey of computational studies, is summarized to document our current mechanistic understanding of EN-catalyzed oxygen, carbon dioxide and nitrogen electrochemistry. We hope this review will inspire future development of synthetic methods and in situ spectroscopic tools to make and study well-defined EN structures.
View details for DOI 10.1038/s41467-021-23486-1
View details for PubMedID 34078884
Exciton Coherence Length and Dynamics in Graphene Quantum Dot Assemblies
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
2020; 11 (1): 210-216
Exciton size and dynamics were studied in assemblies of two well-defined graphene quantum dots of varying size: hexabenzocoronene (HBC), where the aromatic core consists of 42 C atoms, and carbon quantum dot (CQD) with 78 C atoms. The synthesis of HBC and CQD were achieved using bottom-up chemical methods, while their assembly was studied using steady-state UV/vis spectroscopy, X-ray scattering, and electron microscopy. While HBC forms long ordered fibers, CQD was found not to assemble well. The exciton size and dynamics were studied using time-resolved laser spectroscopy. At early times (∼100 fs), the exciton was found to delocalize over ∼1-2 molecular units in both assemblies, which reflects the confined nature of excitons in carbon-based materials and is consistent with the calculated value of ∼2 molecular units. Exciton-exciton annihilation measurements provided the exciton diffusion lengths of 16 and 3 nm for HBC and CQD, respectively.
View details for DOI 10.1021/acs.jpclett.9b03384
View details for Web of Science ID 000506088000033
View details for PubMedID 31842548
Electron Transfer Kinetics at Graphene Quantum Dot Assembly Electrodes
ACS APPLIED MATERIALS & INTERFACES
2019; 11 (49): 46303-46310
Electrochemical performance of nanostructured carbon electrodes was evaluated using cyclic voltammetry and a simple simulation model. The electrodes were prepared from soluble precursors by anodic electrodeposition of two sizes of graphene quantum dot assemblies (hexabenzocoronene (HBC) and carbon quantum dot (CQD)) onto a conductive support. Experimental and simulated voltammograms enabled the extraction of the following electrode parameters: conductivity of the electrodes (a combination of ionic and electronic contributions), density of available electrode states at different potentials, and tunneling rate constant (Marcus-Gerischer model) for interfacial charge transfer to ferrocene/ferrocenium (Fc/Fc+) couple. The parameters indicate that HBC and CQD have significant density of electronic states at potentials more positive than -0.5 V versus Ag/Ag+. Enabled by these large densities, the electron transfer rates at the Fc/Fc+ thermodynamic potential are several orders of magnitude slower than those commonly observed on other carbon electrodes. This study is expected to accelerate the discovery of improved synthetic carbon electrodes by providing fast screening methodology of their electrochemical behavior.
View details for DOI 10.1021/acsami.9b14161
View details for Web of Science ID 000502689000100
View details for PubMedID 31729857
- Conformational analysis of diols: Role of the linker on the relative orientation of hydroxyl groups JOURNAL OF PHYSICAL ORGANIC CHEMISTRY 2019; 32 (10)
Cocatalysis: Role of Organic Cations in Oxygen Evolution Reaction on Oxide Electrodes
ACS APPLIED MATERIALS & INTERFACES
2018; 10 (32): 26825-26829
Cocatalysis is a promising approach toward enhanced electrocatalytic activity. We report such synergic catalysis involving organic xanthylium-based catalyst, Xan2+, and oxides formed on the electrode surface. The oxygen evolution reaction (OER) was observed on some working electrodes (gold, platinum, glassy carbon, boron-doped diamond), while others (titanium and fluorine-doped tin oxide) exhibited no OER activity. On the basis of experimental data and supported by calculations, we propose a mechanism in which oxidized Xan2+ activates electrode toward the rate-determining O-O bond formation. In light of our findings, efficient OER electrocatalysis can be achieved using materials that strongly bind oxygen species and electron-deficient organic cations.
View details for DOI 10.1021/acsami.8b10232
View details for Web of Science ID 000442460400002
View details for PubMedID 30063133
Metal-Free Motifs for Solar Fuel Applications
ANNUAL REVIEW OF PHYSICAL CHEMISTRY, VOL 68
2017; 68: 305-331
Metal-free motifs, such as graphitic carbon nitride, conjugated polymers, and doped nanostructures, are emerging as a new class of Earth-abundant materials for solar fuel devices. Although these metal-free structures show great potential, detailed mechanistic understanding of their performance remains limited. Here, we review important experimental and theoretical findings relevant to the role of metal-free motifs as either photoelectrodes or electrocatalysts. First, the light-harvesting characteristics of metal-free photoelectrodes (band energetics, exciton binding energies, charge carrier mobilities and lifetimes) are discussed and contrasted with those in traditional inorganic semiconductors (such as Si). Second, the mechanistic insights into the electrocatalytic oxygen reduction and evolution reactions, hydrogen evolution reaction, and carbon dioxide reduction reaction by metal-free motifs are summarized, including experimental surface-sensitive spectroscopy findings, studies on small molecular models, and computational modeling of these chemical transformations.
View details for DOI 10.1146/annurev-physchem-052516-050924
View details for Web of Science ID 000401335600015
View details for PubMedID 28301760
- Conformational flexibility of xanthene-based covalently linked dimers JOURNAL OF PHYSICAL ORGANIC CHEMISTRY 2016; 29 (10): 505-513