Synthesis of FeP nanotube arrays as negative electrode for solid-state asymmetric supercapacitor

Recently, metal phosphides have attracted considerable attention as promising electrode materials for supercapacitors. In this work, FeP nanotube arrays have been successfully synthesized on carbon cloth using ZnO nanorod arrays as the sacrificial templets, via a phosphidation process. The dimensions of the FeP nanotubes are characterized using SEM and TEM showing the diameter to be approximately 200 nm and with a wall thickness of 50-100 nm. The tubular structure of FeP nanotubes provides a facile ion pathway and reduced inner inactive material, thus they are favorable for supercapacitor applications. As a result, the as-synthesized FeP nanotube arrays deliver an improved specific capacitance of 149.11 F g-1 and a high areal capacitance of 300.1 mF cm-2 at a current density of 1 mA cm-2. Furthermore, an MnO2//FeP solid-state asymmetric supercapacitor was fabricated with a high areal capacitance of 142 mF cm-2, which indicates the great potential of FeP nanotube arrays to be a high-performing negative electrode material for supercapacitors.