Nanostructured TiO₂-Based Hydrogen Evolution Reaction (HER) Electrocatalysts: A Preliminary Feasibility Study in Electrodialytic Remediation with Hydrogen Recovery

The use of electrodialytic (ED) technology in soil remediation is to date primarily limited by energy costs related to the stirring and the potentiostat power supply. Considering that during ED process water splitting reactions are the main electrodic reactions involved, one of the strategies to minimize ED energy costs is based on the by-produced hydrogen recovery and reuse (as energy vector) in tandem connected power production units (e.g. fuel cells). From this perspective, using effective electrocatalysts would further boost energy savings by minimizing overpotentials required to sustain the electrolysis. To this purpose, the present study investigated the possibility of employing non-noble-metal-based electrodes as effective hydrogen evolution reaction (HER) electrocatalysts. Specifically, TiO₂ nanotubes (NTs) based electrodes have been synthesized and characterized in comparison with commercial electrodes generally employed in ED processes (i.e. Ti/MMO (mixed metals oxides) electrodes). The preliminary characterization evidenced as greater hydrogen production has been achieved using TiO₂ NTs based electrode (as cathodes) rather than the commercial one. Furthermore, considering the remediation/recovery targets of the ED tests performed, employing the TiO₂ NTs based electrode higher extraction yields for W and Sn were observed, while comparable yields with the commercial electrode were observed for As and Cu.