The size- shape- and composition-dependent optoelectronic properties of semiconducting metal chalcogenide (MC) nanoparticles (NPs) make them promising materials for sustainable energy production processes such as solar power conversion and photocatalysis. Assembling NPs into 2-D and 3-D architectures that possess short and robust interparticle linkages is essential for diverse energy-related applications that require efficient charge transport through the structure. The oxidative gelation approach has been successfully deployed to assemble metal chalcogenide NPs obtained by solution phase synthetic routes into 2-D thin films and 3-D gel structures. However, oxidized surfaces resulting from the assembly mechanism and the consequent instability of the ultimate gel network in the presence of reducing chemicals hinders their performance and applicability in energy related applications. Therefore, it is necessary to discover alternative strategies to assemble NPs without compromising their performance and/or to bring effective modifications to the current gelation approach to overcome existing drawbacks. To address the redox instability problem, oxidized dichalcogenide linkers (Q--Q-; Q= S, Se) produced by oxidative gelation are modified by treatment with oxidative addition reagents such as Ni(COD)2 (COD- cyclooctadiene) and Fe(CO)5. We hypothesize that, like organic dichalcogenides, the inorganic dichalcogenide linkages will react with these reagents to reduce Q--Q- bonds to 2Q2- with insertion of M2+ (M= Ni, Fe) to form a dative bond. Redox stability of oxidatively assembled ZnS and CdSe aerogels modified with oxidative addition reagents will be compared to that of untreated aerogels and aerogels produced by the metal ion cross-linking of sulfide-ligand capped NPs.

Effect of oxidative gelation on the redox stability of metal chalcogenide gels:  Modification of nanoparticle-nanoparticle dichalcogenide interfaces obtained from the oxidative gelation mechanism

2019 Spring National Meeting

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