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 -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.