Bionic Janus membranes to manipulate bubbles underwater for hydrogen evolution reactions

Manipulation of bubbles underwater is attracting a wide range of interests due to the immense potential applications for industry, human health, etc. Inspired by superaerophilic legs of the water strider, a unique type of superaerophilic/aerophobic Janus membrane with precisely controllable geometric parameters and morphologies for unidirectional transportation of bubbles underwater is proposed and fabricated by projection micro-stereolithography (P μ SL) based 3D printing technique. The bionic Janus membranes possess different wettability on their two sides, which enables them stable and ultra-fast unidirectional bubbles transportation underwater. The superhydrophobic microholes forbid the water entering them but provide numerous gas channels, which is dominated by the superaerophilic coating (nano-SiO 2 ). Most significantly, we apply our bionic Janus membranes for the ultra-fast removal of hydrogen bubbles adhering to the copper cathode during the hydrogen evolution reaction (HER). The amazing performance of our 3D printed bionic Janus membranes promises applications in terms of ultra-fast unidirectional gas transportation underwater, such as fast gas–liquid separation, bubble collection, gas removal for chemical reaction, and so on.