GALVANOSTATIC GRAPHITE ELECTROACTIVATION FOR HYDROGEN PEROXIDE ELECTROSYNTHESIS BY MULTI-SEQUENCE AND AUTO-ADAPTIVE TECHNIQUES

Abstract

Electrochemical oxidation/reduction of carbonaceous electrodes represents a simple and inexpensive way for in-situ electroactivation (EA), increasing the electrocatalytic activity toward hydrogen peroxide electrosynthesis (HPE). In this context, our previous results obtained by cyclic hydrodynamic voltammetry (CHV) and an original potentiostatic multi-sequence electroactivation technique (MSET) revealed that the graphite anodization followed by the surface partial reduction has a positive effect upon the HPE efficiency. Unfortunately, CHV is not suitable for industrial approaches and the use of MSETs in potentiostatic mode induces prohibitive electrical energy consumptions during the EA steps. In order to overcome these drawbacks, in this work, new galvanostatic MSETs were designed and tested in hydrodynamic controlled conditions using a Pt/graphite wall-jet ring disk electrode system. The galvanostatic approach diminished significantly the electrical energy used for graphite EA (under 30 % from the global consumption) and improved HPE efficiency up to 35 % compared to the unmodified graphite. The best results were obtained when original auto-adaptive protocols were used. Finally, in the attempt to eliminate the energy waste during the EA steps, we proposed the use of a symmetrical divided reactor with periodic inversion of the electrodes function and the feasibility of this idea was also tested with very promising results.