{"id":{"repo_id":"buffalo","oai_identifier":"oai:ubir.buffalo.edu:10477/86485"},"canonical_url":"https://search.dev.ndltd.org/etd/buffalo/oai:ubir.buffalo.edu:10477/86485","repository":{"repo_id":"buffalo","name":"Buffalo","base_url":"https://ubir.buffalo.edu/oai/request"},"display":{"title":"Multiscale Modeling of Charge Dynamics in Photoelectrocatalytic Systems","abstract":"Ph.D.","abstract_html":"Ph.D.","abstract_has_math":false,"creators":["Pasumarthi, Viswanath; 0000-0001-8104-4918"],"institution":"State University of New York at Buffalo","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Dupuis, Michel","Chemical and Biological Engineering"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-02-21T17:22:53Z","date_published":"2025-02-21T17:22:53Z","updated_at":"2026-07-27T19:05:32Z","subjects":["computational chemistry","materials science","chemical engineering"],"languages":["eng"],"rights":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10477/86485","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dupuis, Michel","Chemical and Biological Engineering"]},{"key":"dc:creator","label":"Author","values":["Pasumarthi, Viswanath; 0000-0001-8104-4918"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2025-02-21T17:22:53Z","2020"]},{"key":"dc:publisher","label":"Institution","values":["State University of New York at Buffalo"]},{"key":"dc:type","label":"Dc Type","values":["Text","Dissertation"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["computational chemistry","materials science","chemical engineering"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/10477/86485"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Ph.D.","The Holy Grail in efficient and cost-effective conversion of solar energy into electrical and chemical energy is solar energy-driven water splitting using semi-conductor-based photo-catalysts. Overall conversion efficiencies of the best systems so far are however far from the level needed for practical applications. Viable materials must exhibit good visible light absorption and carrier generation, good carrier transport, and good redox reactivity. A fundamental understanding of the charge carrier dynamics will inform the extent to which the photocatalytic performance of the material can be improved. While the charge properties in the form of diffusion length, mobility and lifetime can be determined using a wide variety of spectroscopic, time- and frequency-resolved measurements, an atomistic perspective of the fundamental carrier dynamics can unlock a new avenue for performance enhancement that is only possible through computational modeling. This dissertation work focuses on investigating collective behavior of charge carrier transport in photoelectrocatalytic systems intended towards enhancing carrier transport and separation features. We employed multiscale modeling, combining DFT+U calculations of polaron hopping by Marcus/Holstein theory and kinetic Monte Carlo (KMC) modeling of mesoscale transport. We developed a KMC based computational model called PyCD (Python-based Charge Dynamics) to characterize the collective charge dynamics in crystalline systems by modeling the multiscale physics of interaction and carrier dynamics. Employing this modeling framework, we investigated the charge carrier dynamics in stoichiometric bulk BiVO4 (BVO), the most promising anode material to date for solar water splitting: simulations reveal that hole transport is bi-modal and confirm that charge carrier transport in BVO is gated by e- transport. We also conducted mesoscale characterization of charge transport physics in sulfur anion incorporated BVO. We found sulfur atoms substitutes in pairs, and arrange to result in a uniquely anisotropic doping distribution. Electronic scale calculations using DFT revealed a transformation in the nature of hole transport with sulfur incorporation. Mesoscale hole transport calculations showed the hole mobility is increased with sulfur incorporation, which is validated by experimental observations. Anisotropic analysis of charge transport has allowed us to derive synthesis guidelines for facet selectivity in BVO-based photoelectrode designs. We also performed a mesoscale characterization of electron transport in W/Mo-doped BVO. A comprehensive set of electronic scale calculations indicated the existence of shallow interaction regions around W/Mo dopant atoms acting as 'soft-traps' for electron carriers. Yet, the material conductivity is found to be improved with doping contributed by the motile excess electron carriers from dopants. Current efforts are focused towards characterizing charge transport in complex systems such as W/Mo gradient-doped BVO homojunctions towards enhanced charge separation, finite-sized nanocrystals towards facet selectivity.","**To request an accessible version of the file(s) associated with this item, contact library@buffalo.edu. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.**"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Multiscale Modeling of Charge Dynamics in Photoelectrocatalytic Systems"]}]}],"canonical_facts":{"dc:contributor":["Dupuis, Michel","Chemical and Biological Engineering"],"dc:creator":["Pasumarthi, Viswanath; 0000-0001-8104-4918"],"dc:date":["2025-02-21T17:22:53Z","2020"],"dc:description":["Ph.D.","The Holy Grail in efficient and cost-effective conversion of solar energy into electrical and chemical energy is solar energy-driven water splitting using semi-conductor-based photo-catalysts. Overall conversion efficiencies of the best systems so far are however far from the level needed for practical applications. Viable materials must exhibit good visible light absorption and carrier generation, good carrier transport, and good redox reactivity. A fundamental understanding of the charge carrier dynamics will inform the extent to which the photocatalytic performance of the material can be improved. While the charge properties in the form of diffusion length, mobility and lifetime can be determined using a wide variety of spectroscopic, time- and frequency-resolved measurements, an atomistic perspective of the fundamental carrier dynamics can unlock a new avenue for performance enhancement that is only possible through computational modeling. This dissertation work focuses on investigating collective behavior of charge carrier transport in photoelectrocatalytic systems intended towards enhancing carrier transport and separation features. We employed multiscale modeling, combining DFT+U calculations of polaron hopping by Marcus/Holstein theory and kinetic Monte Carlo (KMC) modeling of mesoscale transport. We developed a KMC based computational model called PyCD (Python-based Charge Dynamics) to characterize the collective charge dynamics in crystalline systems by modeling the multiscale physics of interaction and carrier dynamics. Employing this modeling framework, we investigated the charge carrier dynamics in stoichiometric bulk BiVO4 (BVO), the most promising anode material to date for solar water splitting: simulations reveal that hole transport is bi-modal and confirm that charge carrier transport in BVO is gated by e- transport. We also conducted mesoscale characterization of charge transport physics in sulfur anion incorporated BVO. We found sulfur atoms substitutes in pairs, and arrange to result in a uniquely anisotropic doping distribution. Electronic scale calculations using DFT revealed a transformation in the nature of hole transport with sulfur incorporation. Mesoscale hole transport calculations showed the hole mobility is increased with sulfur incorporation, which is validated by experimental observations. Anisotropic analysis of charge transport has allowed us to derive synthesis guidelines for facet selectivity in BVO-based photoelectrode designs. We also performed a mesoscale characterization of electron transport in W/Mo-doped BVO. A comprehensive set of electronic scale calculations indicated the existence of shallow interaction regions around W/Mo dopant atoms acting as 'soft-traps' for electron carriers. Yet, the material conductivity is found to be improved with doping contributed by the motile excess electron carriers from dopants. Current efforts are focused towards characterizing charge transport in complex systems such as W/Mo gradient-doped BVO homojunctions towards enhanced charge separation, finite-sized nanocrystals towards facet selectivity.","**To request an accessible version of the file(s) associated with this item, contact library@buffalo.edu. Please include the item's persistent URL [http://hdl.handle.net/. . .] in your request.**"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/10477/86485"],"dc:language":["eng"],"dc:publisher":["State University of New York at Buffalo"],"dc:rights":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."],"dc:subject":["computational chemistry","materials science","chemical engineering"],"dc:title":["Multiscale Modeling of Charge Dynamics in Photoelectrocatalytic Systems"],"dc:type":["Text","Dissertation"]},"updated_at":"2026-07-27T19:05:32Z"}