Hetero-N-Coordinated Co Single Sites with High Turnover Frequency for Efficient Electrocatalytic Oxygen Evolution in an Acidic Medium

Abstract

The development of noble-metal-free, acid-compatible oxygen electrocatalysts and monitoring their active sites’ evolution under working conditions are crucial for global renewable energy storage and conversion. Here, we present a new type of hetero-N-coordinated Co (HNC-Co) single sites, with Co active centers bonding to hetero pyridinic- and amino-N ligands, as an efficient oxygen evolution reaction (OER) electrocatalyst in an acidic medium. The atomically dispersed HNC-Co electrocatalyst could effectively oxidize water at a quite low overpotential of 265 mV at 10 mA cm–2 in 0.5 M H2SO4 solution with an ultrahigh turnover frequency of 2.8 s–1 and a huge mass activity of 7.6 A mg–1, ∼80–240 times that of commercial IrO2. By using operando synchrotron infrared spectroscopy, a potential-driven active site evolution of H2N–(*O–Co)–N4 is observed for the first time during the OER process, which greatly promotes the surface oxo-species transformation for efficient acidic OER catalysis.

Exposing unsaturated Cu 1 -O 2 sites in nanoscale Cu-MOF for efficient electrocatalytic hydrogen evolution

“…3B) show that only a dominant peak at about 1.50 Å, evidently contributed from the nearest coordination shell of Cu-O bonds (37,38), is observed for both Fe(OH) x @Cu-MOF NBs and Cu-MOF NPs. This suggests a dispersed planar Cu 1 -O x configuration of Cu nodes in both Fe(OH) x @Cu-MOF NBs and Cu-MOF NPs (39,40). Notably, Fe(OH) x @Cu-MOF NBs show a weaker Cu-O peak relative to that of Cu-MOF NPs, possibly indicating the presence of partial coordinatively unsaturated Cu nodes.…”

Modifying redox properties and local bonding of Co3O4 by CeO2 enhances oxygen evolution catalysis in acid

“…As a result, there have been very limited choices of earth-abundant OER catalysts that are both active and stable in acidic media 17 – 20 . Cobalt (Co)-based catalysts such as Ba[Co-POM] 17 , hetero-N-coordinated Co single atom catalyst 21 , CoFePbO x 18 , Co 2 TiO 4 22 , and Co 3 O 4 23 – 25 are promising for acidic OER; however, the mechanistic details have rarely been studied for these emerging OER catalysts in acidic media.…”

Dipole Field Interactions Determine the CO2 Reduction Activity of 2D FeNC Single Atom Catalysts

“…4 Single-atom catalysts which consist of earthabundant elements such as Fe, Co, and Ni doped on a support material such as graphene, have emerged as promising alternatives to Au. [5][6][7] Very recently, FeNC catalysts, fabricated through pyrolysis on defected graphene and characterized within a gas-diffusion electrode showed an impressive geometric current density of 100 mA/cm 2 with Faradaic efficiency toward CO greater than 90% at -0.4 V vs. RHE. This high activity was suggested to arise from tailored Fe sites with a +3 oxidation state.…”