PEC Electrode Connections

Several methods are commonly used to prepare PEC electrodes, but many similar techniques should work as long as they fulfill some basic requirements (1) a large area ohmic contact to provide uniform potential distribution, (2) electrical and chemical isolation of all conductive hardware (wires, contacts, electrode edges, etc.) from the electrolyte except for the planar working electrode (WE) surface. In this section, two different electrode mounting techniques are presented as examples. 

1 Electrode Connection Using Insulated Electrical Wires 

Connection to an electrode using insulated electrical wires is performed in live steps  

Many epoxies contract as they cure. This contraction may lead to cracking of the semiconductor film, exposing the underlying metallic contact to the electrolyte. In this case, an O-ring seal to the electrolyte is recommended. 

Another variation of making an electrode connection is shown in Fig. 3.2. In this case, bare copper wire is inserted into a glass tube and coiled at the end. The coiled wire is attached to the back side of the sample using silver paint and allowed to dry at 80 °C for 20-30 min. The entire assembly is then encased in epoxy and annealed at 80 °C for 2 h. 

---

Fig. 3.1 Main steps of PEC electrode connection using plastic insulated wires, (a) WO3 film on FTO and wiring, (b) Adding a coat of indium solder to the uncovered FTO. (c) Soldering the wires to the indium, (d) Coating the electrically conductive wiring and substrate with nonconductive epoxy...

---