As an earth-abundant and inexpensive first-row transition metal, cobalt is a good candidate for the development of water oxidation catalysts. The (bpy)2Co (bpy = 2,2'-bipyridine) molecular motif offers stable and functional electrocatalytic water oxidation, while substituents on the bipyridyl group offer a ready means for attachment to materials. Data are consistent with the Co(II) complex (bpy)2Co(NO3)2 (1-H) serving as an active and robust catalyst in neutral aqueous conditions with a catalytic potential (Ecat) of 1.3 V vs NHE at a scan rate of 20 mV s-1 in 0.1 M phosphate buffer and an estimated turnover frequency of 40 s-1. A series of (Ybpy)2CoX2 complexes (Ybpy = 4,4'-disubstituted bpy ligands with Y = NH2 or NO2; X = NO3 or Cl) were synthesized and tested for electrocatalytic water oxidation to determine the effect of electron-withdrawing and electron-donating substituents on electrocatalytic activity. Additionally, the diamino-substituted complex (4,4'-NH2bpy)2Co(NO3)2 (1-NH2) serves as an avenue of approach for the functionalization of carbon-based material supports and the development of heterogeneous water oxidation catalysts. Complex 1-NH2 was utilized to append the (bpy)2Co motif to carbon-materials derived from the hydrothermal carbonization (HTC) of monosaccharide starting materials via diazotization. Alternatively, addition of 4,4'-divinyl-2,2'-bipyridine during the HTC synthesis provided a carbon material with pre-ligated coordination sites, which allowed for direct metalation with simple metal salts such as CoCl2●6H2O or CoNO3●6H2O.

Electrocatalytic water oxidation using (bpy)2Co-based precursors

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.