Graphical A mesh film was prepared by coating polypyrrole (PPy) film on Ti mesh , which is underwater superaerophilic when PPy is doped with perfluorooctanesulfonate ions (PFOS − ), and becomes underwater superaerophobic as the PFOS − are removed. The transition of the wettability can be triggered by the electro-stimuli, and adjustable bubble permeation in water is also demonstrated based on the film. Recently, materials with controllable superwettability have attracted much attention. However, almost all studies focused on controlling wetting of water and oil; research on underwater gas bubble wetting control is still rare. Herein, we report a mesh film prepared by coating polypyrrole (PPy) film on Ti mesh. Briefly, the film mesh is underwater superaerophilic when PPy is doped with perfluorooctanesulfonate ions (PFOS − ), and becomes underwater superaerophobic as the PFOS − are removed. The transition of the wettability can be triggered by electrical stimuli, which is attributed to the cooperative effect between the rough structure and chemical components variation. The controllable wettability allows adjustable bubble permeation. It can be envisioned that the film will provide potential applications in the future, such as underwater bubble capture/release and microfluidic devices.
Zhaolong Wang,Jinsong Xiong,Yibo Liao,Mingzhu Xie,Dongsheng Yang,Ce Zhang,Yongping Chen,Zhigang Zou
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.
Hydrogen evolution reaction (HER), as an effective method to produce green hydrogen, is greatly impeded by inefficient mass transfer, i.e., bubble adhesion on electrode, bubble dispersion in the vicinity of electrode, and poor dissolved H2 diffusion, which results in blocked electrocatalytic area and large H2 concentration overpotential. Here, we report a superaerophilic/superaerophobic (SAL/SAB) cooperative electrode to efficiently promote bubble transfer by asymmetric Laplace pressure and accelerate dissolved H2 diffusion through reducing diffusion distance. Benefiting from the enhanced mass transfer, the overpotential for the SAL/SAB cooperative electrode at −10 mA cm−2 is only −19 mV, compared to −61 mV on the flat Pt electrode. By optimizing H2SO4 concentration, the SAL/SAB cooperative electrode can achieve ultrahigh current density (−1867 mA cm−2) at an overpotential of −500 mV. We can envision that the SAL/SAB cooperative strategy is an effective method to improve HER efficiency and stimulate the understanding of various gas-involved processes.
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