# Experimental Performances of Titanium Redox Electrodes as the Substitutes for the Ruthenium–Iridium Coated Electrodes Used in the Reverse Electrodialysis Cells for Hydrogen Production

## TL;DR

This paper explores using titanium electrodes instead of expensive ruthenium-iridium ones in reverse electrodialysis to produce hydrogen more affordably.

## Contribution

The study introduces titanium redox electrodes with a spike structure to improve hydrogen production efficiency and reduce costs in RED systems.

## Key findings

- Optimized titanium electrodes achieved 89.7% of the hydrogen yield of traditional ruthenium-iridium electrodes.
- Electrode costs were reduced by over 60% using titanium-based alternatives.
- Operating parameters like temperature and rinse solution concentration significantly affect system performance.

## Abstract

Reverse electrodialysis (RED) enables the efficient conversion of the chemical potential difference between seawater and freshwater into electricity while simultaneously facilitating hydrogen production for integrated energy utilization. Nevertheless, the widespread deployment of RED remains constrained by the reliance on ruthenium–iridium-coated electrodes, which are expensive and resource-limited. This study proposes the adoption of titanium-based redox electrodes as a replacement for traditional precious metal electrodes and employs a novel spike structure to accelerate hydrogen bubble detachment. The electrochemical performance of titanium electrodes in an RED hydrogen production system was systematically evaluated experimentally. The influences of several parameters on the RED system performance were systematically examined under these operating conditions, including the ruthenium–iridium catalytic layer, operating temperature (15 to 45 °C), electrode rinse solution (ERS) concentration (0.1 to 0.7 M), and flow rate (50 to 130 mL·min−1). Experimental results demonstrate that optimized titanium redox electrodes maintain high electrocatalytic activity while significantly reducing system costs. Under optimal conditions, the hydrogen yield of the Ti redox electrode reached 89.7% of that achieved with the mesh titanium plate coated oxide iridium and oxide ruthenium as electrodes, while the electrode cost was reduced by more than 60%. This is also one of the cost-cutting solutions adopted by RED for its development.