A parametric study of the carbon black slurry electrode

Abstract

Slurry electrodes in 1 M H 3PO 4 made from carbon blacks with specific surface areas ranging from 28 to 1475 m 2 g −1 were studied by cyclovoltammetry (5 mV s −1) at potentials ranging from −0.1 V to +2.3 V vs. SHE. The main parameters affecting the electrode performance were investigated in detail, i.e., carbon black concentration C R , stirring rate n, voltage scan rate v s , feeder material and structure, and potential of positive scan reversal. High stirring rates ( n > 100 rpm) were crucial as well as low voltage scan rates ( v s < 10 mV s −1) and an inert feeder of Pt or Au with a grid structure. Smooth sheets and other materials were inefficient. Optimal carbon black concentrations C R were in the range of 0.1–1 g/l. Only at the very positive potentials of scan reversal, quoted above, could all features of the anodic current voltage curves, charging of a large double layer capacity at low potentials and irreversible surface oxidation at more positive potentials be observed. All findings can be rationalized with a model of a thin layer adhering to the feeder electrode in a steady state.