Scanning electrochemical microscopy for studying electrocatalysis on shape-controlled gold nanoparticles and nanorods

The electrocatalytic activity for the oxygen reduction reaction (ORR) of different shape-controlled gold nanoparticles (NPs) and nanorods has been studied by scanning electrochemical microscopy (SECM). TEM images and lead underpotential deposition (UPD) voltammetric profiles were used to physically and electrochemically characterize all gold particles studied here, providing information on the shape and surface structure of the different NPs and nanorods. The SECM results demonstrate that cubic gold NPs are the most active towards ORR in 0.1 M NaOH, followed by the spherical gold NPs and, finally, by the short gold nanorods. These results are in agreement with previous studies using conventional electrochemical techniques with gold NPs and single crystal electrodes, since they established that higher ratio of (1 0 0) domains provide higher catalytic activity for ORR.