Insights on the Electrochemical Atomic Force Microscopic Catalytic Oxygen Reduction on Tip Guided Platinum Particle Deposits

Oxygen reduction reaction (ORR) is traditionally studied on electrodes of large surface covered with a layer of catalysts. However it is important to understand the oxygen reduction reaction occurring on separated catalytic metal particles of different morphology, size and also to probe the hydrogen peroxide byproduct, if any, generated during the reduction process. Therefore, it is necessary to produce metal particles under controlled electrochemical conditions that will allow concomitant high resolution imaging. Herein, we have used a relatively less explored technique- ‘Electrochemical Atomic Force Microscopy (EC-AFM)’ to do controlled electrodeposition and subsequently image the catalytic platinum particles deposited on conductive carbon substrates on a nanometric scale. AFM tip electrodes were used to direct the deposition of platinum particles while simultaneously scanning the substrate. We have presented the effect of deposition parameters including tip scan rate, platinum salt concentration and electrodeposition time on the nature of platinum deposits and oxygen reduction activity of these deposits.