Seawater Electrolysis Anode Selectivity (2D Bubble & Kinetics Lab)

Splitting seawater directly for green hydrogen is chemically ambushed by one side reaction: the chloride ions that make up ~0.55 M of seawater will evolve toxic, corrosive chlorine gas at the anode far faster than they let it make oxygen, unless the catalyst and electrolyte conditions are deliberately tuned against it. This 2D lab renders a cross-section of the anode surface, nucleating and releasing green O₂ bubbles and red Cl₂ bubbles from a Butler–Volmer-style kinetic competition between the oxygen evolution reaction (OER) and the chlorine evolution reaction (CER), driven by four real controls — chloride concentration, local pH, applied current density, and catalyst selectivity (from bare noble-metal anodes to engineered Ni-Fe layered double hydroxides). A draggable, zoomable chamber view and a live strip chart track the Cl₂ Faradaic efficiency, the OER–CER overpotential gap that governs the split, the local pH shift at the anode, and the resulting chlorine production rate — the exact numbers seawater-electrolysis researchers optimise to keep direct hydrogen production chlorine-free.