BEGIN:VCALENDAR VERSION:2.0 X-WR-CALNAME:EventsCalendar PRODID:-//hacksw/handcal//NONSGML v1.0//EN CALSCALE:GREGORIAN BEGIN:VTIMEZONE TZID:America/New_York LAST-MODIFIED:20240422T053451Z TZURL:https://www.tzurl.org/zoneinfo-outlook/America/New_York X-LIC-LOCATION:America/New_York BEGIN:DAYLIGHT TZNAME:EDT TZOFFSETFROM:-0500 TZOFFSETTO:-0400 DTSTART:19700308T020000 RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU END:DAYLIGHT BEGIN:STANDARD TZNAME:EST TZOFFSETFROM:-0400 TZOFFSETTO:-0500 DTSTART:19701101T020000 RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU END:STANDARD END:VTIMEZONE BEGIN:VEVENT CATEGORIES:College of Arts and Sciences,Thesis/Dissertations DESCRIPTION:Title: Single-particle spectroelectrochemistry on electrodeposi ted palladium nano particles Advisor: Dr. Wei-Shun Chang, Associate Profes sor, Chemistry & Biochemistry Dept. Committee Members: Dr. Patrick Cappill ino, Associate Professor, Graduate Program Director, Chemistry & Biochemis try Dept.; Dr. Milana Vasudev, Associate Professor, Bioengineering Dept. A bstract:  Palladium nanoparticles drive chemical innovation due to their high surface-to-volume ratio and tunable quantum properties. Their ability to readily activate hydrogen and form stable lattices makes them a corner stone of modern chemistry. Therefore, to optimize chemical performance, co ntrolling size and density during synthetic processes is critical because these two factors dictate the catalyst's reactivity, stability, and cost-e fficiency. While wet synthesis is an excellent approach to facilitate part icle size and shape, surface ligands/surfactants removal together with par ticle immobilization on substrates remain problematic.  Electrodeposition offers precise, template-free, and ligand-free control by tuning electroc hemical parameters. In this dissertation, electrodeposition of Pd nanopart icles with controlled size and density on indium-doped tin oxide substrate was firstly carried out using a combination of fast potential pulse and c hronoamperometry techniques. As confirmed by electrochemical data and anal ysis of scanning electron microscopy images, a lower concentration of acti ve species in the electrolyte solution results in a lower density of Pd nu clei during the nucleation step, and a larger particle size during the gro wth step. Meanwhile, at the same nuclei density, a higher concentration of active species gives larger particle size during the growth phase. This a pproach provides convenient means of fabricating nanostructures on substra tes with desired sizes and densities and sheds light on the mechanism of g rowth. Secondly, in another approach, the growth of single Pd nanoparticle s can be monitored with the power of dark-field microscope during electroc hemical experiments. Through analyzing light scattering intensity of Pd nu clei exposing to a constant flow rate of electrolyte solution and chronoam perometric potential in a flow cell, a corresponding mechanism for the ele ctrodeposition was uniquely obtained. This technique reveals a possibility to utilize optical data as a source of information in order to further un derstand the electrochemical processes at single particle level as opposed to average data retrieved from ensemble current. Lastly, we demonstrate a single-particle optical cyclic voltammetry technique that tracks hydrogen sorption dynamics in individual electrodeposited Pd nanoparticles by conv erting electrochemical processes into optical signals. This high-throughpu t method captures absorption and desorption across thousands of particles at once, bridging single-particle mechanisms with bulk statistical analysi s. The technique exposes severe interparticle and intraparticle heterogene ity, along with cycling-induced deactivation caused by surface reorganizat ion and deep trapping sites. Interestingly, the individual potential profi les show symmetric kinetic behavior via consistent shifts and broadening. These findings confirm that electrochemical activity is inherently heterog eneous and evolves dynamically under operando conditions. Ultimately, sing le-particle optical cyclic voltammetry offers a universal framework for ma pping structure-activity relationships in energy materials, highlighting n anoscale behaviors that traditional ensemble measurements completely miss. \nEvent page: https://www.umassd.edu/events/cms/9-1-26-defense-by-trang-n- nguyen-single-particle-spectroelectroch.php X-ALT-DESC;FMTTYPE=text/html:

Title: Single-particle spectroe lectrochemistry on electrodeposited palladium nano particles

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Advis or: Dr. Wei-Shun Chang\, Associate Professor\, Chemistry & Biochemistry De pt.

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Committee Members: Dr. Patrick Cappillino\, Associate Professo r\, Graduate Program Director\, Chemistry & Biochemistry Dept.\; Dr. Milan a Vasudev\, Associate Professor\, Bioengineering Dept.

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Abstract:  Palladium nanoparticles drive chemical innovation due to their high surf ace-to-volume ratio and tunable quantum properties. Their ability to readi ly activate hydrogen and form stable lattices makes them a cornerstone of modern chemistry. Therefore\, to optimize chemical performance\, controlli ng size and density during synthetic processes is critical because these t wo factors dictate the catalyst's reactivity\, stability\, and cost-effici ency. While wet synthesis is an excellent approach to facilitate particle size and shape\, surface ligands/surfactants removal together with particl e immobilization on substrates remain problematic.  Electrodeposition off ers precise\, template-free\, and ligand-free control by tuning electroche mical parameters. In this dissertation\, electrodeposition of Pd nanoparti cles with controlled size and density on indium-doped tin oxide substrate was firstly carried out using a combination of fast potential pulse and ch ronoamperometry techniques. As confirmed by electrochemical data and analy sis of scanning electron microscopy images\, a lower concentration of acti ve species in the electrolyte solution results in a lower density of Pd nu clei during the nucleation step\, and a larger particle size during the gr owth step. Meanwhile\, at the same nuclei density\, a higher concentration of active species gives larger particle size during the growth phase. Thi s approach provides convenient means of fabricating nanostructures on subs trates with desired sizes and densities and sheds light on the mechanism o f growth. Secondly\, in another approach\, the growth of single Pd nanopar ticles can be monitored with the power of dark-field microscope during ele ctrochemical experiments. Through analyzing light scattering intensity of Pd nuclei exposing to a constant flow rate of electrolyte solution and chr onoamperometric potential in a flow cell\, a corresponding mechanism for t he electrodeposition was uniquely obtained. This technique reveals a possi bility to utilize optical data as a source of information in order to furt her understand the electrochemical processes at single particle level as o pposed to average data retrieved from ensemble current.

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Lastly\, w e demonstrate a single-particle optical cyclic voltammetry technique that tracks hydrogen sorption dynamics in individual electrodeposited Pd nanopa rticles by converting electrochemical processes into optical signals. This high-throughput method captures absorption and desorption across thousand s of particles at once\, bridging single-particle mechanisms with bulk sta tistical analysis. The technique exposes severe interparticle and intrapar ticle heterogeneity\, along with cycling-induced deactivation caused by su rface reorganization and deep trapping sites. Interestingly\, the individu al potential profiles show symmetric kinetic behavior via consistent shift s and broadening. These findings confirm that electrochemical activity is inherently heterogeneous and evolves dynamically under operando conditions . Ultimately\, single-particle optical cyclic voltammetry offers a univers al framework for mapping structure-activity relationships in energy materi als\, highlighting nanoscale behaviors that traditional ensemble measureme nts completely miss.

Event page: https://www.umassd.edu/events/cms/9-1-26-defense-by-trang-n-nguyen-si ngle-particle-spectroelectroch.php

DTSTAMP:20260810T211623 DTSTART;TZID=America/New_York:20260901T130000 DTEND;TZID=America/New_York:20260901T150000 LOCATION:VIOL 210 SUMMARY;LANGUAGE=en-us:Single-particle spectroelectrochemistry on electrode posited palladium nano particles UID:e4405df622a5d4eac997429bc11d7399@www.umassd.edu END:VEVENT END:VCALENDAR