Screening of Oxygen Reduction and Evolution Electrocatalysts By Scanning Electrochemical Microscopy

A rapid screening technique based on scanning electrochemical microscopy (SECM) in a tip-generation–substrate-collection (TG–SC) mode was applied to identify potential electrocatalysts for both oxidation reduction reaction (ORR) and oxidation evolution reaction (OER). Ternary ruthenium based chalcogenide and ruthenium based oxide electrocatalyst arrays were fabricated and screened for ORR and OER, respectively. The potential electrocatalysts were then characterized by SEM, EDX, XRD and XPS. The catalytic activity of potential electrocatalysts were further examined during cyclic voltammetric scans of the substrate with a tip close to the substrate. The quantitative rate of ORR on the candidate substrates was determined for different substrate potentials from SECM approach curves by fitting to a theoretical model. The electron transfer number of OER was calculated rotating ring-disk electrode (RRDE) technique. The best ruthenium based electrocatalysts for ORR and OER would be identified in this work.