Solid-state dispersions of isolated single-walled carbon nanotubes (SWCNTs) in polymer matrices or networks of electronically coupled SWCNTs are gaining interest for a broad variety of optoelectronic applications. However, little is known about either the stability or degradation mechanisms of these systems. We show dramatic sp 2 -to-sp 3 defect transformations of the SWCNT sidewall when either the S 11 or S 22 exciton transitions are optically pumped in ambient conditions, leading to the rapid decay of absorption and emission properties in less than 24 h for conditions similar to exposure to solar illumination. Importantly, we demonstrate that either (i) encapsulation to block reactive O 2 from SWCNT excited states or (ii) exciton quenching via donor-to-acceptor electron transfer is an effective route for "kinetic stabilization" against photodegradation, with <8% loss in absorbance after 1200 h of illumination. We find that SWCNT:polymer loading does not impact degradation. Our study suggests that the sp 3 defects are associated with the formation of oxygenic groups on the SWCNT sidewall. While such defect populations can detrimentally evolve over time in films where SWCNTs are environmentally exposed in the presence of light, we offer multiple pathways to arrest this degradation and enable their robust application as advanced optical materials in optical and electronic devices.
Nanoparticulate Au, Ag, and Cu films with percolating ion-conducting polymers are common within devices for the electroreduction of carbon dioxide (CO2) to carbon monoxide, hydrocarbons, and alcohols. The kinetics of ion-transfer are influential on the rate of corrosion and catalyst sintering, but direct measurements of ion-transfer rates are challenging at bulk metal electrodes. We present data on the corrosion kinetics of metal nanoclusters and monolayers deposited via underpotential deposition on well-oriented and/or single-crystal metal surfaces within suspended ionomer electrolytes. Our results support the important role of nucleation and growth in corrosion processes as well as the influence of structural anions on reactive intermediates present during corrosion reactions.
Figure 1
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.