Quasi-Chimney Electrode Boosts Hydrogen Evolution Reaction via Polarized Laplace Pressure.

The effect of mass transfer on hydrogen evolution reaction (HER) is significantly underestimated under high-current-density conditions. Here, we designed a quasi-chimney electrode by integrating 3D superaerophilic microchannels with superaerophobic Pt catalysts to elucidate the influence of mass transfer on HER. Upon encountering superaerophilic channels, hydrogen (H₂) bubbles generated on Pt catalysts experience Laplace pressure polarization at the bubble/channel interface, which drives both surface and internal bubbles from the superaerophobic catalytic sites into the superaerophilic network, functioning as a micro-chimney for efficient bubble transport. In addition, the superaerophilic channels shorten the diffusion path of dissolved H₂ to the air/water interface, thereby reducing the dissolved H₂ concentration. This mass-transfer enhancement yields an exceptional HER performance (a record-low overpotential of about -30 mV at -100 mA cm⁻², and a high current density of -2.93 A cm⁻² at -0.3 V vs RHE in H₂SO₄ (0.5 M) along with remarkable durability, confirmed by <5% activity decay at -1000 and -2000 mA cm⁻² for 160 h. The proposed quasi-chimney design, which is also applicable to various catalysts, results in an 8- and 14-times increase in current density for Cu-Co and Cu-Mo catalysts, at an overpotential of -500 mV compared with their superaerophobic electrode structures.