3D imaging-informed electrode engineering for water splitting

Abstract

Gas bubble accumulation limits mass transport in porous electrodes during alkaline water electrolysis at high current densities. Herein, synchrotron-based operando micro-CT and microstructure-resolved lattice Boltzmann method simulations are employed to unveil how porosity and geometric structure govern hydrogen bubble detachment and two-phase transport in alkaline water electrolysis. It is found that porous electrodes with a rationally designed ordered pore architecture enable efficient mass transport by minimizing gas trapping and promoting continuous electrolyte renewal. By contrast, commercial nickel foams with low porosity, despite their larger surface area, exhibit severe gas accumulation and poor electrode utilization. Guided by these insights, we 3D-printed a highly ordered square-grid electrode and, following catalyst deposition, achieved high-efficiency overall water splitting at 2 A cm⁻² with a cell voltage of 2.13 V. This methodology, integrating operando micro-CT and lattice Boltzmann method simulations, delivers much-needed design rules for gas evolving porous electrodes and demonstrates that tuning a 3D pore architecture is critical for advanced alkaline water electrolysis.