Electrocatalysis of oxygen on single crystal gold electrodes

Shape‐Dependent Electrocatalysis: Oxygen Reduction on Carbon‐Supported Gold Nanoparticles

“…The Au octahedra had a somewhat low SA value, and similarly to the results obtained in acidic solution, the highest SA was determined for Au nanocubes. This order of activities is in agreement with studies on Au single-crystal electrodes, [21] which show that Au(111) is the least active and Au(100) the most active single-crystal plane, and it confirms the results of previous O 2 reduction studies on shape-controlled AuNPs. [12] As expected, the MA increased in the following order: Au octahedra % Au cubes < 30 nm Au spheres < 5 nm Au spheres.…”

“…This is in accordance with the previous studies, in which it has been determined that the Au(100) is the most active single-crystal surface for ORR. [21,22] As expected, the smallest Au particles (5 nm spheres) demonstrated the highest mass activity.…”

“…The absolute values of the Tafel slope are slightly higher than the typical value of À120 mV, which suggests that the rate-determining step is the transfer of the first electron to an O 2 molecule. Similarly, more-negative slope values have been previously observed for some Au single-crystal electrodes [21,22] and Au/ C catalysts. [47] In addition, morenegative Tafel slope values due to the porosity of the catalyst have been obtained in case of thick catalyst layers, [77] however, in this work the catalyst loading was much lower and presumably the reaction was not limited by thin-layer diffusion, as confirmed for Au/C catalysts of various loadings.…”

“…[20] The highest ORR activity of Au(100) among low-index crystal planes in acidic media has been suggested to be caused by structural effects. [21,22] More recently, it has been shown on the basis of spectroscopic data that the ORR takes place via a series mechanism where peroxide is the reaction intermediate in alkaline media, [23] and the formation of adsorbed superoxide species is also evident. [24] In contrast, the reduction of O 2 proceeds only through a two-electron process, yielding H 2 O 2 as the final product on all Au single-crystal faces in acidic media.…”

Activation Effect of Electrochemical Cycling on Gold Nanoparticles towards the Hydrogen Evolution Reaction in Sulfuric Acid

“…The formation of this OA1 peak is complicated. Some reports [18,34,35] have associated it with an increase of the surface defects [36,37] while others suggest the electrodeposition of OH and O species on the anion free surface of the electrode [30,38]. In a paper by Compton [18], decreased electroactivity of the ORR was observed on gold nanoparticles with an increased intensity of this peak.…”