Critical role of intercalated water for electrocatalytically active nitrogen-doped graphitic systems.

Graphitic materials are essential in energy conversion and storage because of their excellent chemical and electrical properties. The strategy for obtaining functional graphitic materials involves graphite oxidation and subsequent dissolution in aqueous media, forming graphene-oxide nanosheets (GNs). Restacked GNs contain substantial intercalated water that can react with heteroatom dopants or the graphene lattice during reduction. We demonstrate that removal of intercalated water using simple solvent treatments causes significant structural reorganization, substantially affecting the oxygen reduction reaction (ORR) activity and stability of nitrogen-doped graphitic systems. Amid contrasting reports describing the ORR activity of GN-based catalysts in alkaline electrolytes, we demonstrate superior activity in an acidic electrolyte with an onset potential of ~0.9 V, a half-wave potential (E ½) of 0.71 V, and a selectivity for four-electron reduction of >95%. Further, durability testing showed E ½ retention >95% in N2- and O2-saturated solutions after 2000 cycles, demonstrating the highest ORR activity and stability reported to date for GN-based electrocatalysts in acidic media.

Tetraalkylphosphonium-based ionic liquids for a single-step dye extraction/MALDI MS analysis platform.

Room temperature ionic liquids, or RTILs, based on tetraalkylphosphonium (PR(4)(+)) cations were used as the basis of a platform that enables separation of dyes from textiles, extraction of dyes from aqueous solution, and identification of the dyes by MALDI-MS in a single experimental step for forensic purposes. Ionic liquids were formed with PR(4)(+) cations and ferulate (FA), α-cyano-4-hydroxycinnamate (CHCA), and 2,5-dihydroxybenzoate (DHB) anions. The use of tetraalkylphosphonium-based ionic liquids in MALDI-MS allowed detection of small molecule dyes without addition of a traditional solid MALDI matrix.