Geometrically periodic architecture for enhanced mass transport in electrocatalysis.

Electrochemical energy conversion reactions are central to sustainable energy technologies, yet their efficiency at industrially relevant current densities is often constrained by mass-transfer limitations. Here, we introduce a periodic flow field strategy for enhancing mass transfer based on a geometrically periodic microstructure that induces spatially varying velocity fields and wall shear oscillations within the pores, generating a coherent convective contribution to otherwise diffusion-dominated transport. To implement this concept, we design hierarchical ordered interconnected porous nickel electrodes with long-range order, tunable structural periods and scalable centimeter-scale fabrication, serving as a general electrocatalyst support. The resulting architecture alleviates mass-transfer constraints across multiple electrochemical reactions. As a representative example, the NiFe-modified electrode delivers a current density of 7 A cm-2 for the oxygen evolution reaction at 25 °C with an overpotential of 393 mV, while an anion-exchange-membrane water electrolyzer sustains 1 A cm-2 at 1.68 V for 1083 h at 60 °C. We also construct a lightweight flexible device for portable oxygen and hydrogen production with efficient operation under fluctuating solar power.