Rotating Disk Electrode - Online Electrochemical Mass Spectrometry for Oxygen Reduction Reaction on Pt Electrode Surfaces

摘要

Potential-dependent molecular behavior of dissolved O_2 in the vicinity of a polycrystalline Pt electrode surface was studied in O_2-saturated 0.1 M HClO_4 solution using a newly developed online electrochemical mass spectrometry (OLEMS) with rotating disk electrode (RDE) method (RDE-OLEMS). A gas sampling tip was positioned at ～50 μm from the electrode surface; O_2 concentration in the vicinity of the Pt electrode at open circuit potential (～0.8 V vs. RHE) depended on the disk rotation rates, and linear sweep voltammetry (LSV) of the Pt electrode showed diffusion-limiting currents in the RDE-OLEMS layout. Furthermore, simultaneously recorded RDE-OLEMS data for the potential-dependent O_2 concentration were consistent with the LSV data recorded for a negative-going sweep. We have successfully applied the newly developed RDE-OLEMS method and it is effective for in-situ analysis of gaseous electrochemical reaction products and dissolved molecules in the vicinity of the electrode under electrochemical conditions.