Unidirectional transport and effective collection of underwater CO2 bubbles utilizing ultrafast-laser-ablated Janus foam

摘要： Manipulating gas bubbles in aqueous ambient is of great importance for applications in water treatment, gas collection and matter transport. Here, a kind of Janus foam is designed and fabricated by one-step ultrafast laser ablation of one side of cooper film, which is treated to be superhydrophobic. The Janus foam exhibits not only the capability of unidirectional transport of underwater bubbles, but also gas collection with favorable efficiency up to ~15 mL cm-2 min-1. The underlying physical mechanism is attributed to the cooperation of the buoyancy, adhesion and wetting gradient forces imposed on the bubbles. As a paradigm, the underwater chemical reaction between unidirectional CO2 gas flow and alkaline phenolphthalein solution is demonstrated via the Janus foam. This facile and low-cost fabrication approach for Janus foam will find broad potential applications for effective bubble transport, carbon capture and controllable chemical reactions in aqueous conditions.