Risko, Chad

A&S College, Chemistry Department

One topic that is not covered in this document that I submitted in a few other applications is related to metal-oxide interface chemistry of interest for Li-ion batteries.

Project 1. Design of Catalysts for Oxidative Depolymerization of Lignin

Lignin, a potential source of renewable aromatics, is currently an underutilized plant-based byproduct of the pulp and paper industry. Products from lignin simplification have vast potential, both as fine chemicals and as intermediates for the production of fuels. Due to its complex, irregular, and insoluble nature, models of lignin linkages are often used to develop lignin depolymerization strategies. One of the key steps in lignin depolymerization is the oxidation of benzylic alcohol groups, which comprise up to 66% of lignin’s connectivity, to a ketone group. Here, models will be developed to investigate how metal nanoparticles supported on layered double hydroxides (LDH) act as catalysts for the oxidation of lignin. Thermodynamic reaction pathways and kinetic barriers for the oxidation of model alcohols will be developed. The molecular-scale details of this study, which will entail catalyst systems that show both poor and robust performance, will allow for the design of new generations of catalysts.

We are developing a collaboration with the group of Mark Crocker (Chemistry; CAER) to establish models of the catalytic activity of LDH-supported metal nanoparticles for the depolymerization of lignin. We would like to request dlx access for one of Dr. Crocker’s students, Yang (Vanessa) Song, as well as access to VASP. A research description for the project from Dr. Crocker is above.

Software:

VASP, Gaussian09, NWChem, QChem

Researchers:

Mark Crocker (PI); Yang Song

Christopher Mullins (P/T Faculty)

UK Collaborator:

Chad Risko

Morphology dependence of the electronic and optical properties of the active layers of organic solar cells

Organic photovoltaics (OPVs), whose active layers are multicomponent thin films derived from electron-rich (donor) and electron-deficient (acceptor) materials, are compelling as a means to advance solar energy harvesting as a wide-scale, alternative energy source. The realization of the bulk heterojunction (BHJ) thin-film architecture, progress in the synthetic design of small optical-gap materials, and a variety of processing refinements have led to certified single-junction OPVs with power conversion efficiencies (PCEs) over 9%. Nonetheless, refinements are needed to the theoretical understanding of device operation to continue to push OPVs towards a viable technology. The underlying processes of photocurrent generation in OPVs, as compared to inorganic solar cells, are complex and heavily dependent on local molecular morphologies. The complexity of the BHJ thin-film structure is vast as it can contain amorphous and well-ordered phase-separated bulk-like domains and amorphous, mixed interlayers as a function of component miscibility. Here, we will investigate the condensed-matter relationships between thin-film morphology and photocurrent generation by employing a combination of theoretical methodologies – ranging from quantum-mechanical calculations to derive electronic and optical properties through MD simulations to provide insight into how chemical structure impacts local molecular packing to CG dynamics simulations to study morphology at device relevant scales.

Students

Adam Rigby, Postdoc
Shi Li
Maxwell Duff, Undergraduate

Asare Nkansah, Undergraduate 08/28/2017
Allen William Smith, Undergraduate 08/31/2017
Kate Elizabeth Fraser, Undergraduate 01/18/2018

Camron DeVine, 05/18/2018
Stephen Goodlett, Undergraduate 08/29/2018
Uma Shantini Ramasamy
Parker D Sornberger 02/04/2020

Andrew J Smith 02/04/2020 

Conner Callaway, Postdoc 02/04/2020

Eesh Kulshrestha, added 06/09/2021

Kehinde H Fagbohungbe, added 06/09/2021

Tenzin Nangsel, External User, added 06/22/2021

Moses D Ogbaje, Added 08/23/2021

Corey A Roberts, Added 08/31/2021

Sashen A Ruhunage, Added 09/07/2021

Antonio Alcaraz, Added 12/08/2021 on LCC cluster

Ling-Yi Huang, Added 07/29/2022 on MCC cluster

Jordan M Chelle, Added on MCC cluster on 09/18/2022

Megan R Brown, Added on LCC cluster on 10/31/2022 

Sahar Bayat, Added on LCC cluster on 11/03/2022 

Shasanka Lamichhane, Added on LCC cluster on 11/22/2022 

Vijaykumar Karthikeyan, Added on MCC cluster on 01/04/2023 

Kyle n Eldridge, Added on LCC cluster on 01/12/2023 

Parker D Sornberger, Added on MCC cluster on 01/18/2023 

Zachary T Gardner, Added on LCC and MCC clusters, 06/07/2023 

Software

LAMMPS, GROMACS, Gaussian09

Collaborators

Sean M Ryno, Kaust Solar Center

Structure-packing-function relationships of crystalline organic electronic materials

π-conjugated molecular materials, whose properties can be tuned via the extensive toolbox of the synthetic chemist, offer distinctive characteristics that will enable a transformation in electronic devices. Here, quantum-chemical calculations will be used to understand how chemical composition impacts molecular structure and packing, and the resulting charge-carrier transport properties of organic semiconductors. Particular emphasis will be placed on the non-covalent interactions that determine molecular structure and packing and the relationship to electronic and optical properties.

Students

Kristen M Brooks, Undergraduate (summer 2016 + 1 yr)
Shi Li
Tristan Finn
Karol Jarolimek, Postdoc
Qianxiang Ai
Chamikara Karunasena, Graduate
Brandyn Thompson, Undergrad 08/28/2017

Software

Gaussian09, VASP, ADF

Collaborator

John Anthony, Faculty Chemistry

Nano-scale processes in composite metal-oxide electrodes for batteries and supercapacitors

Lithium ion batteries (LIB) hold great promise as energy storage systems across many applications, from mobile devices through transportation to smart grids. However, significant scientific and technological challenges remain to increase LIB energy density and integrity. In this program, we will investigate the chemical processes that occur within and at the surface of metal-oxide nanoparticles of interest for use in LIB composite electrodes. Our focus will be to determine: (i) the structural rearrangements of bulk and surface metal oxides, as a function of Li ion concentration, doping, and surface terminations, and the subsequent impact on the electronic and redox properties; (ii) thermodynamic pathways of Li ion insertion into metal oxides; and (iii) interactions and reactions at the metal oxides surface with carbon-based materials and electrolytes and the potential for controlled surface modification to manipulate these processes. State-of-the-art electronic-structure calculations and molecular-dynamics simulations will be used to detail key differences between bulk and surface metal-oxide physicochemical properties and delineate how the metal-oxide surface structure, coupled with the composition of the electrolyte, regulate transport and chemical reactivity at the metal-oxide−electrolyte interface.

Students

Corrine Elliot
Karol Jarolimek, Postdoc
Qianxiang Ai
Nick Telesz, UG

Software

VASP, Gaussian09

Collaborator

Susan Odom, Faculty Chemistry

Software

Gaussian, QChem, VASP, Turbomole, Crystal, PSI4, NWChem, ADF, GROMACS, GPUs and LAMMPS

Thermogalvanic Cells for Scavenging Waste Heat

The objective of this work is to establish the fundamental basis of understanding required to develop new generations of thermogalvanic cells (TC) that can efficiently scavenge low-grade (<130 °C) thermal energy for conversion to electrical energy. With an understanding founded through state-of-the-art electronic-structure methods and molecular-dynamics simulations, combined with synthesis and device characterization, this work will delineate how redox couple structure and ionic liquid composition regulate TC power output. Our focus will be to determine: (i) how the choice of metal center, ligand structure, and coordination geometry affect the activity of the redox couple; (ii) to what extent does the make-up of the ionic liquid components – including ion size, charge density, and polarization – determine the solubility and diffusion of the redox couple; and (iii) explicit connections between the chemical structure and oxidation state of the redox couple, chemical make-up of the ionic liquid, and resulting entropic contributions to the Seebeck coefficient. State-of-the-art electronic-structure calculations and molecular-dynamics simulations will be used to detail key differences between redox-couple and ionic liquid physicochemical properties. We will use the information generated for known species to determine in silico chemical design pathways to develop redox-couple–electrolyte formulations to reduce exploration cost and time.

Software:

Gaussian09

Researchers:

Chad Risko (PI);
Tristan Finn

UK Collaborator:

Cameron Lippert (CAER)

Grants:

Publications:

2023

2022

Large Variability and Complexity of Isothermal Solubility for a Series of Redox-Active Phenothiazines. A.S. Perera, T.M. Suduwella, N.H. Attanayake, R.K. Jha, W.L. Eubanks, I. Shkrob, C. Risko, A.P Kaur & S.A. Odom. Materials Advances (2022), 3, 8705-8715. DOI: 10.1039/D2MA00598K

The Role of Crystal Packing on the Optical Response of Trialkyltetrelethynyl Acenes. L.Y. Huang, Q. Ai & C. Risko. Journal of Chemical Physics (2022), 157, 084703. DOI: 10.1063/5.0097421