Using auxiliary electrochemical working electrodes as probe during contact glow discharge electrolysis: A proof of concept study

Abstract

Plasma in-liquid by means of anodic contact glow discharge electrolysis (aCGDE) is a growing research field allowing the selective modification of the electrode and the electrolyte. The aim of this proof of concept study is to demonstrate that auxiliary electrochemical electrodes placed in the vicinity of the plasma electrode can be modified by aCGDE (ignited at the anode by applying a DC voltage between the driving electrodes). Furthermore, we illustrate in how far such auxiliary electrodes can be used as a probe to detect products (in particular, H2, H2O2, and O2) formed in the solution by aCGDE via electrochemical techniques. In this work, aCGDE is achieved by applying a voltage of 580 V to a small Pt wire (plasma electrode) versus a large stainless steel counter electrode. An auxiliary Pt electrochemical working electrode, operated in a three electrode configuration, is placed at different distances from the plasma working electrode. Depending on the distance, we find small changes in the working electrode structure. More importantly, we will show that, in principle, the local H2O2 concentration in the electrolyte can be monitored operando. After aCGDE, the concentration changes with time and depends on the distance from the plasma electrode.