14 research outputs found
Nanoscale Limitations in Metal Oxide Electrocatalysts for Oxygen Evolution
Metal oxides are attractive candidates
for low cost, earth-abundant
electrocatalysts. However, owing to their insulating nature, their
widespread application has been limited. Nanostructuring allows the
use of insulating materials by enabling tunneling as a possible charge
transport mechanism. We demonstrate this using TiO<sub>2</sub> as
a model system identifying a critical thickness, based on theoretical
analysis, of about ∼4 nm for tunneling at a current density
of ∼1 mA/cm<sup>2</sup>. This is corroborated by electrochemical
measurements on conformal thin films synthesized using atomic layer
deposition (ALD) identifying a similar critical thickness. We generalize
the theoretical analysis deriving a relation between the critical
thickness and the location of valence band maximum relative to the
limiting potential of the electrochemical surface process. The critical
thickness sets the optimum size of the nanoparticle oxide electrocatalyst
and this provides an important nanostructuring requirement for metal
oxide electrocatalyst design
Nanoscale Investigation of Solid Electrolyte Interphase Inhibition on Li-Ion Battery MnO Electrodes via Atomic Layer Deposition of Al 2
Reversible temperature-controlled gelation in mixtures of pNIPAM microgels and non-ionic polymer surfactant
Efficient Bifunctional Fe/C/N Electrocatalysts for Oxygen Reduction and Evolution Reaction
Rheological Behaviors and Miscibility of Mixture Solution of Polyaniline and Cellulose Dissolved in an Aqueous System
Electrocatalytic oxygen evolution over supported small amorphous ni-fe nanoparticles in alkaline electrolyte
The electrocatalytic oxygen evolution reaction (OER) is a critical anode reaction often coupled with electron or photoelectron CO2 reduction and H2 evolution reactions at the cathode for renewable energy conversion and storage. However, the sluggish OER kinetics and the utilization of precious metal catalysts are key obstacles in the broad deployment of these energy technologies. Herein, inexpensive supported 4 nm Ni-Fe nanoparticles (NiyFe1-yOx/C) featuring amorphous structures have been prepared via a solution-phase nanocapsule method for active and durable OER electrocatalysts in alkaline electrolyte. The Ni-Fe nanoparticle catalyst containing 31% Fe (Ni0.69Fe0.31Ox/C) shows the highest activity, exhibiting a 280 mV overpotential at 10 mA cm -2 (equivalent to 10% efficiency of solar-to-fuel conversion) and a Tafel slope of 30 mV dec-1 in 1.0 M KOH solution. The achieved OER activity outperforms NiOx/C and commercial Ir/C catalysts and is close to the highest performance of crystalline Ni-Fe thin films reported in the literature. In addition, a Faradaic efficiency of 97% measured on Ni 0.69Fe0.31Ox/C suggests that carbon support corrosion and further oxidation of nanoparticle catalysts are negligible during the electrocatalytic OER tests. Ni0.69Fe0.31O x/C further demonstrates high stability as there is no apparent OER activity loss (based on a chronoamperometry test) or particle aggregation (based on TEM image observation) after a 6 h anodization test. The high efficiency and durability make these supported amorphous Ni-Fe nanoparticles potentially applicable in the (photo)electrochemical cells for water splitting to make H2 fuel or CO2 reduction to produce usable fuels and chemicals. © 2014 American Chemical Society