From fibrous elastin proteins to one-dimensional transition metal phosphides and their applications

One-dimensional (1D) carbon-supported nanostructured CoP and FeP₄ were prepared using fibrous elastin proteins that served as starting materials through an oil-phase method and the as-synthesized products were investigated for their lithium and sodium storage properties. The 1D CoP and FeP₄ are composed of nanosized particles decorated on carbon supports. The 1D CoP and FeP₄ nanostructures are ∼2 μm in length and 20-50 nm in diameter. The particles on the exterior of the 1D structure are 5-10 nm in diameter. To investigate the as-synthesized 1D TMPs in energy storage applications, the as-synthesized 1D CoP nanostructures are applied as an anode material in half-cells for LIBs and SIBs. For lithium storage performances, the anode delivers a specific capacity as high as ∼740 mAh g^-1 at 0.2C and shows good rate performance and capacity retention as well as high rate capability (e.g. a stable specific capacity of ∼365 mAh g^-1 for 120 cycles at 3.0C). In SIBs, at 0.2 and 5.0C, the specific capacities of 491.60 and 314.84 mAh g^-1 are delivered, respectively. When tested at 1.0, 2.0, and 5.0C, the specific capacities are stable at ∼400, 360, and 300 mAh g^-1 over 250, 250, and 1000 cycles, respectively.