Getting Membrane with Membrane Approach: 3D Polypyrrole Nanotube Array Membranes and Their Applications

Conductive polymers, owing to their excellent properties such as good conductivity and chemical stability, have been extensively studied for various applications, especially in the fields of energy and environmental science. Three-dimensional (3D) conductive polymer structures, containing interconnected and continuous networks with high specific surface areas, are encouraging platforms with superior performance. Despite the rapid advances in nanofabrication technology, achieving conductive polymer superstructures with ordered features remains challenging, such as in aligned nanochannels. Herein, we report a facile and efficient template synthesis method to fabricate 3D polypyrrole membrane structures. Using flexible, track-etched polycarbonate membranes as the template, polypyrrole nanotube arrays can be synthesized by chemical polymerization with tunable length and diameter. Free-standing, 3D nanotube array membranes with vertically aligned channels and continuous connecting layers were obtained simply by template removal. This “getting membrane with membrane” approach is also scalable and low-cost. We further demonstrated that the delicate membrane structures can be used in various applications, including adsorbents, solar steaming materials, gas sensors, and supercapacitors. It exhibited quick and excellent adsorption performance for Cr(VI) ions; can be directly served as a solar interfacial evaporator without surface modification and substrate support; showed extraordinary sensing response toward NH3, displayed great potential for energy storage materials with satisfactory electrochemical performance. Our work provides a feasible way to fabricate polypyrrole superstructures and expands the applications of 3D conductive polymer materials.