3D-Printing Starfish-Inspired Gas-Evolving Electrode Scaffolds Enable Ampere-Level Alkaline Water Electrolysis.

Abstract

Alkaline water electrolysis (AWE) mitigates the high cost and immaturity of polymer electrolyte membrane-based water electrolysis (PEMWE) for green hydrogen production. However, its industrial application at ampere-level current densities (ACDs) remains challenging. Conventional disordered gas-evolving electrode (GEE) scaffolds endow with sluggish bubble detachment kinetics and mechanical instability, preventing operation at high ACDs, while rational scaffold designs for accelerating bubble detachment remain rarely explored. Inspired by starfish scaffolds, we design and fabricate a biomimetic GEE with conical sieve-plate hole scaffolds via 3D printing. Combined COMSOL simulations and in situ bubble behavior analyses reveal that like the breath and mass exchange of starfish, the sieve plate optimizes bubble force balance to accelerate detachment, while the conical structure conducts bubbles rapidly into the electrolyte. Such starfish-inspired GEE design yields a 21-fold lower mass-transfer overpotential vs. current density slope than that of common flat round-hole scaffold. Consequently, champion lowest overpotentials of 159 and 430 mV among all the well-documented state-of-the-art GEEs are achieved at the ACD of 1000 mA cm^-2 for HER and OER, respectively. Moreover, our starfish-inspired GEE sustains ACDs operation with ≈100% Faraday efficiency for over 150 h, demonstrating its potential for practical AWE applications.