New solutions based on 3-D printing for energy: Tailoring saline electrolyzers for hydrogen production

• 3D–printed electrolyzer cells and stacks with robust design. • Dual–use operation: H 2 generation and efficient CO 2 capture. • High mass transfer rate confirms efficient cell flow. • High energy efficiency for H 2 and Cl 2 production in the cell. • Stack triples electrode area while sustaining performance. This work presents the design, manufacture, and evaluation of two photovoltaic-powered chlor-alkali saline electrolyzers developed for integrated hydrogen production, chlorine generation, and caustic soda formation, with potential application in renewable energy storage and CO 2 capture. The study addresses the need for compact, low-pressure electrochemical systems capable of simultaneously producing hydrogen for energy storage and hydroxide for reactive CO 2 absorption. The first device is a single-cell electrolyzer featuring 16 cm 2 perforated electrodes that enable chlorine and hydrogen generation within the same chamber. The second device scales up the concept through a three–cell electrolyzer stack, in which CO 2 fixation occurs in an external reactor. Both systems were constructed using stereolithographic 3–D printing and coupled to a gas compression unit to allow atmospheric-pressure operation while enabling compressed hydrogen storage. The single-cell prototype demonstrated suitable hydrodynamic behavior, with a mass transfer coefficient of 2.24 ± 0.78 × 10 -5 m·s −1 and high Peclet numbers, confirming convection–dominated transport. Electrical performance remained stable, with cell resistances near 1.57 Ω and power requirements between 3.5 and 16.6 W at 50–150 mA·cm −2 . Energy efficiencies reached 202 mg Cl 2 ·Wh −1 , 6.2 mg H 2 ·Wh −1 , and up to 80% faradaic efficiency for OH⁻ generation, enabling complete CO 2 capture (25 mmol) at 15 mL·min −1 . The electrolyzer stack tripled electrode area and maintained strong performance, achieving 10.8 mg H 2 ·Wh −1 and > 190 mg Cl 2 ·Wh −1 . Despite increased mechanical complexity, the stacked configuration showed improved scalability, confirming its potential as a platform for integrated hydrogen generation and CO 2 capture.