Oxygen evolution reaction (OER) is critical to renewable energy conversion technologies, but the structure-activity relationships and underlying catalytic mechanisms in catalysts are not fully understood. We herein demonstrate a strategy to promote OER with simultaneously achieved lattice oxygen activation and enhanced local electric field by dual doping of cations and anions. Rough arrays of Fe and F co-doped CoO nanoneedles are constructed, and a low overpotential of 277 mV at 500 mA cm−2 is achieved. The dually doped Fe and F could cooperatively tailor the electronic properties of CoO, leading to improved metal-oxygen covalency and stimulated lattice oxygen activation. Particularly, Fe doping induces a synergetic effect of tip enhancement and proximity effect, which effectively concentrates OH− ions, optimizes reaction energy barrier and promotes O2 desorption. This work demonstrates a conceptual strategy to couple lattice oxygen and local electric field for effective electrocatalytic water oxidation.
12 July 2017 in Journal of the American Chemical Society
The nature of molecule-electrode interface is critical for the integration of atomically precise molecules as functional components into circuits. Herein, we demonstrate that the electric field localized metal cations in outer Helmholtz plane can modulate interfacial Au-carboxyl contacts, realizing a reversible single-molecule switch. STM break junction and I-V measurements show the electrochemical gating of aliphatic and aromatic carboxylic acids have a conductance ON/OFF behavior in electrolyte solution containing metal cations (i.e., Na+, K+, Mg2+ and Ca2+), compared to almost no change in conductance without metal cations. In situ Raman spectra reveal strong molecular carboxyl-metal cation coordination at the negatively charged electrode surface, hindering the formation of molecular junctions for electron tunnelling. This work validates the critical role of localized cations in the electric double layer to regulate electron transport at the single-molecule level.
6 January 2021 in The Journal of Physical Chemistry Letters